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Full text of "Various contrivances by which orchids are fertilised by insects"

BOOK 58 1.D259 c. 1 

DARWIN # VARIOUS CONTRIVANCES BY 

WHICH ORCHIDS ARE FERTILISED BY I 



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BRITI' LE ST C RAGE 

NOT TO L._: VE 
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TUE o/\ 

VARIOUS CONTRIVANCES \S>\2^ 



BY WHICH 



ORCHIDS ARE FERTILISED BY INSECTS. 



By CHAELES DAKWIN, M.A., F.R.S., &a 



SECOND EDITION, REVISED, 



WITH ILLUSTRATIONS. 



l^EW YOKK: 
D. APPLETON AND COMPANY, 

1, 3, AND 5 BOND STREET. 
1892. 



^ 

-.M:^^ 



PREFACE 



THE SECOND EDITION. 



The first edition of this work was published early in 
the year 1862, and has been for some time out of print. 
During the two or three years after its appearance 
I received, through the kindness of various corre- 
spondents in different parts of the world, a large 
uumber of letters, especially from Fritz Miiller in South 
Brazil, communicating to me many new and curious 
facts, and calling my attention to some errors. Various 
memoirs on the fertilisation of orchids have also since 
been published, and I have myself examined several 
new and striking forms. A large amount of matter 
has thus been accumulated; but the present volume 
would be rendered much too long if the whole were 
introdiiced. I have, therefore, selected only the more 
interesting facts, and have given a brief abstract of 
the several published papers. The work has thus been 
remodelled ; and the additions and corrections are so 
numerous that I have found it impossible to follow my 
usual plan of giving a list of them. I have, however, 



n PREFACE TO THE SECOND EDITION. 

appended, in chronological order, the titles of all the 
papers and books on the fertilisation of the Orchidese 
which have been published since the appearance of 
the first edition of the present book. Finally, I will 
remark that any reader who wishes merely to see how 
wonderfully complex and perfect are the adaptations 
for the fertilisation of these plants had better read 
Chapter VII. on the Catasetidae. The account of 
their structure and of the action of the several parts 
will, I think, be intelligible, if he will first glance at 
the explanation of the terms given at the close of 
the Introduction. 



List of Pampers and Books hearing on the Fertilisation 
of the Orchidese, which have been published since the 
appearance of the First Edition of this Worh in 
1862, arranged in Chronological Order, 



Bronn, H. G. — * Charles Darwin, iiber die Einriclitungen zur Be- 
fruchtimg britischer und auslandischer Orchideen.' With 
an Appendix hy the Translator on Stanhopea devoniensis. 
Stuttgart, 1862. 

Gray, Asa. — On Platanthera {flahenaria) and Gymnadenia in 
* Enumeration of Plants of the Rocky Mountains.' — American 
Journal of Science and Arts, Second Series, vol. xxxiv., No. 
101, Sept. 1862, p. 33. 

Gray, Asa. — On Platanthera hooJcert, in a review of the first edi- 
tion of the present work. — American Journal of Science and 
Arts, vol. xxxiv. July 1862, p. 143. 

Anderson, J. — * Fertilisation of Orchids.* — Journal of Horticulture 
and Cottage Gardener, April 21, 1863, p. 287. 

GossE, P. H. — * Microscopic Observation on some Seeds of Orchids.' 
— Journal of Horticulture and Cottage Gardener, April 21, 
1863, p. 287. 

Gray, Asa. — On Platanthera (Hahernaria) fiava and Gymnadenia 
tridentafa. — American Journal of Science and Arts, vol. xxxvi. 
Sept. 1863, p. 292. 

Journal of Horticulture and Cottage Gardener. — March 17, 
1863, p. 206. ' On Orchid Cultivation, Cross-breeding, and 
Hybridising.* 

Scudder, J. H. — On Pogonia opMoglossoides. Proceedings of the 
Boston Society of Natural Histoiy, vol. ix. April, 1863. 

Tbeviranus. — 'Uebcr Dichogamie nach C. C. Sprengel und Ch. 
Darwin. § 3. Orchideen.'— Botanische Zeitung, No. 2, 1863, 
p. 9. 



irm LIST OF PAPERS AND BOOKS. 

Tbeviranus. — * NachtrUgliche Bemerkungen tiber die Befruchtmig 
einiger Orchideen.' — Botanische Zeitung, No. 32, 1863, p. 
241. 

Tbimen, E. — 'On the Fertilisation of JDisa grandiflora, Linn.' — 
Journal of Linnean Society, Botany, vol. vii. 1863, p. 144. 

West of Scotland Horticultural Magazine. — ' Fertilisation of 
Orchids,' Sept. 1863, p. 65. 

Ceuger. — * A few Notes on the Fecundation of Orchids, and their 
Morphology.' — Journal of Linnean Society, Botany, vol. viii. 
No. 31, 1864, p. 127. 

Scott, J. — ' On the Individual Sterility and Cross-impregnation of 
certain Species of Oncidium.' — Journal of Linnean Society, 
vol. viii. No. 31, 1864, p. 162. 

MoGGRiDGE, J. Traherne. — ' Observations on some Orchids of the 
South of France.' — Journal of Linnean Society, Botany, vol. 
viii. No. 32, 1865, p. 256. 

Trimen, R. — ' On the Structure of Bonatea sjjeciosa, Linn., with 
reference to its Fertilisation.' — Journal of Linnean Society, 
vol. ix. 1865, p. 156. 

EoHRBACH, P. — ^'Ueber Epipogium gmelinV — Gekronte Preisschrift, 
Gottingen, 1866. 

Delpino. — ' Sugli Apparecchi della Fecondazione nelle Piante 
antocarpee.' Florence, 1867. 

Hildebrand, F. — ' Die Geschlechter-Yertheilung bei den Pflanzen,' 
&c. Leipzig, 1867, p. 51, et seq. 

Hildebrand, F. — * Frederigo Delpino's Beobachtungen iiber die 
Bestaubungsvorrichtungen bei den Phanerogamen.' — Bota- 
nische Zeitung, No. 34, 1867, p. 265. 

MoGGRTDGE, J. Traherne, ou Ophrys. — 'Flora of Mentone,' 1867 (?). 
Plates 43, 44, 45. 

Weale, J. P. Mansel. — ' Notes on the Structure and Fertilisation 
of the Genus Bonatea, with a special description of a Species 
found at Bedford, South Africa.' — Journal of Linnean Society, 
Botany, vol x. 1867, p. 470. 

Hildebrand. — 'Notizen liber die Geschlechtsverhaltnisse brasili- 
anischer Pflanzen. Aus einem Briefe von Fritz Miiller.'— 
Botanische Zeitung, No. 8, 1868, p. 113. 



LIST OF PAPERS AND BOOKS. ix 

MtJLLEB, Fritz. — * Ueber Befruchtungserscheimingeii bei OrcM- 
deen.'— Botaniscbe Zeitung, No. 39, 1868, p. 629. 

MtJLLER, Hermann. — ' Beobachtungen an westralishen Orchideen.* 
— Yerhandlungen des nat. Vereins fiir Pr. Rheinl. u. Westf. 
1868 and 1869. 

Darwin, Charles. — ' Notes on the Fertilisation of Orchids.' — 
Annals and Magazine of Natural History, Sept. 1869. 

Delpino. — ' Ulterior! Osservazioni suUa Dicogamia nel Regno vege- 
tale.' Parte prima. Milan, 1868-69, pp. 175-78. 

MoGGBiDGE, J. Traherne. — * UebeT Ophrys insectifera^ L. (part). 
— Yerhandlungen der Kaiserl. Leop. Carol. Akad. (Nova 
Acta), torn. xxxv. 1869. 

MuLLER, Fritz. — * Ueber einige Befruchtungserscheinungen.'— 



MiJLLEB, Fritz. — * Umwandlung von Staubgefassen in Stempel bei 
Begonia. Uebergang von Zwitterbliithigkeit in Getrenntblii- 
thigkeit bei Chamissoa. Triandrische Varietat eines monan- 
drischen Epidendrum.' — Botanische Zeitung, No. 10, 1870, 
p. 149. 

Weale, J. P. Mansel. — * Note on a Species of Disperis found on 
the Kageberg, South Africa.' — Journal of Linnean Society, 
Botany, vol. xiii. 1871, p. 42. 

Weale, J. P. Mansel. — * Some Observations on the Fertilisation 
of Disa macrantha.' — Journal of Linnean Society, vol. xiii. 
1871, p. 45. 

Weale, J. P. Mansel. — * Notes on some Species of Habenaria 
found in South Africa.' — Journal of Linnean Society, vol xiii. 
1871, p. 47. 

Cheeseman, T. F. — *0n the Fertilisation of the New Zealand 
Species of Pterostylis.' — Transactions of the New Zealand Insti- 
tute, vol. V. 1873, p. 352. 

Muller, Hermann. — * Die Befruchtung der Blumen durch Insekten,* 
«fec. Leipzig, 1873, pp. 74-86. 

Cheeseman, T. F. — 'On the Fertilisation of Acianthus cyrtostilis* 
— Transactions of the New Zealand Institute, vol. vii. 1874 
(issued 1875), p. 349. 



X LIST OF PAPERS AlH) BOOKS. 

MtJLLEB, Hermann. — 'Alpine Orchids adapted to Cross-fertilisation 
by Butterflies/— Nature, Dec. 31, 1874. 

Delpino. — * Ulteriori Osservazioni sulla Dicogamia nel Regno 
vegetale.' Parte seconda, fasc. ii. Milan, 1875, pp. 149, 150. 

Lubbock, Sir J. — ' British Wild Flowers.' London, 1875, pp. 162- 
175. 

Fitzgerald, R. D.— * Australian Orchids.' Part L 1875, Part II. 
1876. Sydney, New South Wales. 



CONTENTS. 



Introduction .. Pages 1-5 

CHAPTER I. 

OPHEE-ffl. 

Structure of the flowex of Orcliis mascula — Power of movement of 
the poUinia — Perfect adaptation of the parts in Orchis pyra- 
midalis — Other species of Orchis and of some closely allied 
genera — On the insects which visit the several species, and on 
the frequency of their visits — On the fertility and sterility of 
various Orchids — On the secretion of nectar, and on insects 
being purposely delayed in obtaining it 6-44 

CHAPTER IL 

OPHRE^ — continued. 

Fly and Spider Ophrys — Bee Ophrys, apparently adapted for 
perpetual self-fertilisation, but with paradoxical contrivances for 
intercrossing — Herminium monorchis, attachment of the pol- 
linia to the front legs of insects — Peristylus viridis, fertilisation 
indirectly effected by nectar secreted from three parts of the 
labellum — Gymnadenia conopsea, and other species — Habenaria 
or Platanthera chlorantha and bifolia, their pollinia attached to 
the eyes of Lepidoptera — Other species of Habenaria — Bonatea 
— Disa — Summary on the powers of movement in the iwUinia 

45-79 



3U1 CONTENTS. 

CHAPTER III. 

ARETHUSEJS. 

Cephalanthera grandiflora ; rostellum aborted ; early penetration of 
the pollen-tabes ; case of imperfect self-fertilisation ; cross- 
fertilisation effected by insects which gnaw the labellum — 
Cephalanthera ensi folia — Pogonia — Pterostylis and other 
Australian orchids with the labellum sensitive to a touch — 
Vanilla — Sobralia Pages 80-92 

CHAPTER IV. 

NEOTTEiE. 

Epipactis palustris ; curious shape of the labellum and its import- 
ance in the fructification of the flower — other species of Epi- 
pactis — Epipogium — Goodyera repens — Spiranthes autumnalis ; 
perfect adaptation by which the pollen of a younger flower is 
carried to the stigma of an older flower on another plant — 
Listera ovata ; sensitiveness of the rostellum ; explosion of 
viscid matter; action of insects; perfect adaptation of the 
several organs — Listera cordata — Neottia nidus-avis; its 
fertilisation effected in the same manner as in Listera — Thely- 
mitra, self-fertile 93-127 

CHAPTER V. 

MALAXEJB AND EPIDENDRE-ffiS. 

Malaxis paludosa — Masdevallia, curious closed flowers — Bolbo- 
phyllum, labellum kept in constant movement by every breath 
of air — Dendrobium, contrivance for self-fertilisation — Cattleya, 
simple manner of fertilisation — Epidendrum — Self-fertile Epi- 
dendreae 128-148 



CONTENTS. XIU 

CHAPTER VL 

YANDEX. 

Structure of the column and pollinia — Importance of the elasticity 
of the pedicel ; its power of movement — Elasticity and strength 
of the caudicles — Calanthe with lateral stigmas, manner of 
fertilisation— Angr^cum sesquipedale, wonderful length of nec- 
tary — Species with the entrance into the stigmatic chamhcr 
much contracted, so that the pollen-masses can hardly be 
inserted — Coryanthes, extraordinary manner of fertilisation 

Pages 149-177 



CHAPTER YII. 

VANDEiE continued. — catasetidje. 

Catasetida3, the most remarkable of all Orchids — The mechanism 
by which the pollinia of Catasetum are ejected to a distance and 
are transported by insects — Sensitiveness of the horns of the 
rostellum — Extraordinary diflference in the male, female, and 
hermaphrodite forms of Catasetum tridentatum — Mormodes 
ignea, curious structure of the flowers ; ejection of the pollinia 
— Mormodes luxata — Cycnoches ventricosum, manner of fer- 
tilisation 178-225 



CHAPTER VIII. 

CYPRirEOEiE — HOMOLOGIES OF THE FLOWERS OF ORCUIDB. 

Cypripedium, differs much from all other Orchids — Labellum in 
the form of a slipper with two small orifices by which insects 
can escape — Manner of fertilisation by small bees of the genus 
Andrena — Homological nature of the several parts of the flowers 
of the Orchidese — "Wonderful amount of modification which 
they have undergone 226-246 



XIV CONTENTS. 

CHAPTElt IX. 

GBADATION OF OEGANS, &C. CONCLUDING EEMAKKS. 

Gradation of organs, of the rostellum, of tlie pollen-masses — 
Formation of the caudicle — Genealogical affinities — Secretion 
of nectar — Mechanism of the movement of the poUinia — Uses 
of the petals — Production of seed — Importance of trifling 
details of structure — Cause of the great diversity of structure in 
the flowers of Orchids — Cause of the perfection of the con- 
trivances — Summary on insect-agency — Nature abhors per- 
petual self-fertilisation Page 247-293 



Index 294 



LIST OF WOODCUTS. 



PAOS 

1. Oechis mascula 8 

2. „ „ pollinia of 12 

3. Orchis pyramidalis 18 

4. Moth's head and proboscis, with attached pollinia 31^ 

5. Ophrts muscifeea 46 

6. „ aeanifera 50 

7. „ arachnites 51 

8. „ APIFERA 53 

9. Peristylus viridis 62 

10. Gymnadenia conopsea 65 

11. Habenaria chlorantha 69 

12. Pollinia of habenarla chlorantha and bifolia .. 74 

13. Cephalanthera grandiflora 81 

14. Pterostylis longifolia 87 

15. Epipactis palustris 94 

16. „ latifolla. 101 

17. Spiranthes autumnalis 107 

18. LiSTERA ovata 116 

19. Malaxis paludosa 130 

20. Masdevallia fenestrata 136 

21. Dendrobium chrysanthum 139 

22. Cattleya 144 

23. Diagram illustrative of the structure of the 

Yandex 150 

24. Pollinia of YANDEiE 154 

25. PoLLiNiuM of Ornithocephalus 160 



XVI LIST OF WOODCUTS. 

PAOB 

26. Calanthe masuca 161 

27. coryanthes speciosa 174 

vCatasetum saccatum •j 

30. CaTASETUM TRIDENT atum 194 

31. Monachanthus and Myanthus 199 

32. Mormodes ignea 209 

33. Cycnoches ventricosum 222 

34. • „ „ section through bud .. .. 223 

35. Cypripedium ?27 

36. Transverse section of flower of an Orchid .. 236 

37. EosTELLUM OF Catasetum 256 

38. Disc of Gymnadenia conopsea 272 



P. S. — I am much indebted to Mr. G. B. Sowerby for the pains 
wbich he has taken in making the Diagrams as intelligible as 



ON THE 

FERTILISxiTION OF ORCHIDS 

BY 

INSECTS, 

&c. &c. 



INTKODUCTION. 

The object of the following work is to show that the 
contrivances by which Orchids are fertilised, are as 
varied and almost as perfect as any of the most beauti- 
ful adaptations in the animal kingdom ; and, secondly, 
to show that these contrivances have for their main 
object the fertilisation of the flowers with pollen 
brought by insects from a distinct plant. In my 
volume * On the Origin of Species ' I gave only general 
reasons for the belief that it is an almost universal law 
of nature that the higher organic beings require an 
occasional cross with another individual ; or, which is 
the same thing, that no hermaphrodite fertilises itself 
for a perpetuity of generations. Having been blamed 
for propounding this doctrine without giving ample 
facts, for which I had not sufficient space in that work, 
I wish here to show that I have not spoken without 
having gone into details. 

I have been led to publish this little treatise sepa- 
rately, as it is too large to be incorporated with any 
other subject. As Orchids are universally acknow- 
ledged to rank amongst the most singular and most 



^ INTRODUCTION. 

modified forms in the vegetable kingdom, I have 
thought that the facts to be given might lead some 
observers to look more curiously into the habits of our 
several native species. An examination of their many- 
beautiful contrivances will exalt the whole vegetable 
kingdom in most persons' estimation. I fear, however, 
that the necessary details are too minute and complex 
for any one who has not a strong taste for Natural 
History. This treatise affords me also an opportunity 
of attempting to show that the study of organic beings 
may be as interesting to an observer who is fully con- 
vinced that the structure of each is due to secondary 
laws, as to one who views every trifling detail of 
structure as the result of the direct interposition of the 
Creator. 

I must premise that Christian Konrad Sprengel, in 
his curious and valuable work, * Das entdeckte Geheim- 
niss der Natur,' published in 1793, gave an excellent 
outline of the action of the several parts in the genus 
Orchis ; for he well knew the position of the stigma, 
and he discovered that insects were necessary to remove 
the pollen-masses.* But he overlooked many curious 
contrivances, — a consequence, apparently, of his belief 
that the stigma generally receives pollen from the 
same flower. Sprengel, likewise, has partially described 
the structure of Epipactis ; but in the case of Listera 
he entirely misunderstood the remarkable phenomena 
characteristic of that genus, which has been well de- 
scribed by Dr. Hooker in the 'Philosophical Trans- 



* Delpino has found (' Ult. Os- In this memoir Waetchf r, who 

Borvazioui sulla Dicogamia,' Part does not seem to have been ac- 

ii. 1875, p. loOj amemoir by Waet- quainted with Spiengel's work, 

cher, published in 1801 in Roe- sliows that insects aie necessary 

mer's ' Archiv fUr die Botanik.' t. for the fertilisation of various 

ii. p. 11, which apparently has re- orchids, and describes well the 

ixiained unknown to everyone else. wonderful structure of Neottia. 



INTRODUCTION. 3 

actions' for 1854. Dr. Hooker has given a full and 
accurate account, with drawings, of the structure of 
the parts ; but from not having attended to the agency 
of insects, he did not fully understand the object 
gained. Robert Brown,* in his celebrated paper in the 
* Linnean Transactions,* expresses his belief that insects 
are necessary for the fructification of most Orchids; 
but adds, that the fact of all the capsules on a dense 
spike not infrequently producing seed, seems hardly 
reconcilable with this belief: we shall hereafter find 
that this doubt is groundless. Many other authors 
have given facts and expressed their belief, more or 
less fully, on the necessity of insect-agency in the 
fertilisation of Orchids. 

In the course of the following work I shall have the 
pleasure of expressing my deep obligation to several 
gentlemen for their unremitting kindness in sending 
me fresh specimens, without which aid this work would 
have been impossible. The trouble which several of 
my kind assistants have taken has been extraordinary : 
I have never once expressed a wish for aid or for in- 
formation which has not been granted me, as far as 
possible, in the most liberal spirit. 

EXPLANATION OF TERMS. 

In case any one should look at this treatise who has 
never attended to Botany, it may be convenient to 
explain the meaning of the common terms used. In 
most flowers the stamens, or male organs, surround in 
a ring the one or more female organs, called the pistils. 
In all common Orchids there is only one well-developed 
stamen, which is confluent with the pistils, and they 



Linnean Transactions,' 1833, vol, xvi. p. 704. 



4 INTRODUCTION. 

form together the column. Ordinary stamens consist 
of a filament, or supporting thread (rarely seen in 
British Orchids), which carries the anther ; and within 
the anther lies the pollen or male vivifying element. 
The anther is divided into two cells, which are very 
distinct in most Orchids, so much so as to appear in 
some species like two separate anthers. The pollen in 
all common plants consists of fine granular powder: 
but in most Orchids the grains cohere in masses, which 
are often supported by a very curious appendage, called 
the caudicle. This part and all the other organs will 
hereafter be more fully described and figured under the 
head of the first species. Orchis mascula. The pollen- 
masses, with their caudicles and other appendages, are 
called the polUnia. 

Orchids properly have three pistils or female organs, 
united together, the upper and anterior surfaces of two 
of which form the two stigmas. But the two are often 
completely confluent, so as to appear as one. The 
stigma is penetrated in the act of fertilisation by long 
tubes, emitted by the pollen-grains, which carry the 
contents of the grains down to the ovules or young 
seeds in the ovarium. 

The upper stigma is modified into an extraordinary 
organ, called the rostellum, which in many Orchids 
presents no resemblance to a true stigma. When 
mature it either includes or is altogether formed of 
viscid matter. In many species the pollen-masses are 
firmly attached to a portion of the exterior membrane, 
which, when insects visit the flowers, is removed, 
together with the pollen-masses. This removable 
portion consists in most British Orchids merely of a 
small piece of membrane, with a layer or ball of viscid 
matter underneath, and I shall call it the " viscid disc;" 
but in many exotic species the portion removed is so 



INTRODUCTION. O 

large and so important, tliat one part must be called, 
as before, the viscid disc, and the other part the pedicel 
of the rostellum, to the end of which the pollen-masses 
are attached. Authors have called that portion of the 
rostellum which is removed, the " gland " or " retina- 
culum," from its apparent function of retaining the 
pollen-masses in their places. The pedicel, or pro- 
longation of the rostellum, to which in many exotic 
species the pollen-masses are attached, seems generally 
to have been confounded, under the name of caudicle, 
with the true caudicle of the pollen-masses, though 
their nature and origin are totally different. The part 
of the rostellum which is left after the removal of 
the discs and viscid matter, is sometimes called the 
" bursicula," or " fovea," or " pouch." But it will be 
found convenient to avoid all these terms, and to call 
the whole modified stigma the rostellum — sometimes 
adding an adjective to define its shape ; that portion 
of the rostellum which is removed with the pollen- 
masses being called the viscid disc, together in some 
cases with the pedicel. 

Lastly, the three outer divisions of the flower are 
called sepals, and form the calyx ; but, instead of being 
green, as in most common flowers, they are generally 
coloured, like the three inner divisions or 2^etals of the 
flower. In almost all the species, one of the petals, 
which is properly the upper one, is larger than the 
others and stands on the lower side of the flower, where 
it offers a landing-place for insects, having been carried 
round by the twisting of the ovarium. It is called 
the lower lip or Idbellum, and often assumes most 
singular shapes. It secretes nectar for the sake of 
attracting insects, and is often produced into a spur- 
like nectary. 



OPHRE^. Chap. I. 



CHAPTER I. 

OPHEE^. 

Structure of the flower of Orchis mascula — Power of movement of the 
pollinia — Perfect adaptation of the parts in Orchis pyramidalis — 
Other species of Orchis and of some closely allied genera — On the 
insects which visit the several species, and on the frequency of their 
visits — On the fertility and sterility of various Orchids — On the 
secretion of nectar and on insects being purposely delayed in 
obtaining it. 

Theoughout the following volume I have followed, as 
far as I conveniently could, the arrangement of the 
OrchidesB given by Lindley. The British species 
belong to five of his tribes, the Ophrese, Neotteee, 
Arethusese, MalaxeaB and Cypripedese, but the two 
latter tribes contain each only a single genus. Various 
British and foreign species belonging to the several 
tribes are described in the first eight chapters. The 
eighth also contains a discussion on the homologies of 
the flowers of the Orchideae. The ninth chapter is 
devoted to miscellaneous and general considerations. • 
The Ophrete include most of our common British 
species, and we will begin with the genus Orchis. The 
reader may find the following details rather difficult 
to understand ; but I can assure him, if he will have 
patience to make out the first case, the succeeding ones 
will be easily intelligible. The accompanying diagrams 
(fig. 1, p. 8) show the relative position of the more 
important organs in the flower of the Early Orchis 
(0. mascula). The sepals and the petals have been re- 
moved, excepting the labellum with its nectary. The 



CiiAP. I. ORCHIS MASCULA. i 

nectary is shown only in the side view (ti, fig. A) ; 
for its enlarged orifice is almost hidden in shade in the 
front view (B). The stigma (s) is bilobed, and con- 
sists of two almost confluent stigmas ; it lies under the 
pouch-formed rostellum (r). The anther (a, in B and 
A) consists of two rather widely separated cells, which 
are longitudinally open in front : each cell includes a 
pollen-mass or pollinium. 

A pollinium removed out of one of the two anther- 
cells is represented by fig. C ; it consists of a number 
of wedge-formed packets of pollen-grains (see fig. F, 
in which the packets are forcibly separated), united 
together by excessively elastic, thin threads. These 
threads become confluent at the lower end of each 
pollen-mass, and compose the straight elastic caudicle 
(c, C). The end of the caudicle is firmly attached to 
the viscid disc {d, C), which consists (as may be seen 
in the section of the pouch-formed rostellum, fig. E) 
of a minute oval piece of membrane, with a ball of 
viscid matter on its under side. Each pollinium has 
its separate disc ; and the two balls of viscid matter 
lie enclosed together (fig. D) within the rostellum. 

The rostellum is a nearly spherical, somewhat 
pointed projection (r, figs. A and B) overhanging the 
two almost confluent stigmas, and must be fully de- 
scribed, as every detail of its structure is full of signi- 
ficance. A section through one of the discs and balls 
of viscid matter is given (fig. E) ; and a front view of 
both viscid dies within the rostellum (fig. D) is like- 
wise given. This latter figure (D) probably best 
serves to explain the structure of the rostellum ; but 
it must be understood that the front lip is here con- 
siderably depressed. The lowest part of the anther is 
united to the back of the rostellum, as may be seen 
in fig. B. At an early period of growth the rostellum 



OPHKE^. 



Chap. I. 



Fig. 1. 




Oechis mascula 



Chap. I. ORCHIS MASCULA. 9 



Desceiption of Fig. 1. 



a. anther, consisting of two cells. 
r. rostellum. 
s. stigma. 
Z. labellum. 



n. nectary. 
p. pollen-mass. 

c. caudicle of poUinium. 

d. viscid disc of pollinium. 



A. Side view of flower, with all the petals and sepals cut off except the 

labellum, of which the near half is cut away, as well as the upper 
portion of the near side of the nectary. 

B. Front view of flower, with all sepals and petals removed, except the 

labellum. 

C. One pollinium, showing the packets of pollen-grains, the caudicle, and 

viscid disc. 

D. Front view of the caudicles of both pollinia with the discs lying within 

the rostellum, its lip being depressed. 

E. Section through one side of the rostellum, with the included disc and 

caudicle of one pollinium, lip not depressed. 

F. Packets of pollen-grains, tied together by clastic threads, here eztcudcfl. 

(Copied from Bauer.) 



)U OPHEE^. Chap. I. 

consists of a mass of polygonal cells, full of brownish 
matter, which cells soon resolve themselves into two 
balls of extremely viscid semi-fluid matter, void of 
structure. These viscid masses are slightly elongated, 
almost flat on the top, and convex below. They lie 
quite free within the rostellum (being surrounded by 
fluid), except at the back, where each viscid ball 
adheres to a small portion or disc of the exterior 
membrane of the rostellum. The ends of the two 
caudicles are strongly attached externally to these 
two little discs of membrane. 

The membrane forming the whole exterior surface 
of the rostellum is at first continuous ; but as soon as 
the flower opens the slightest touch causes it to rupture 
transversely in a sinuous line, in front of the anther- 
cells and of the little crest or fold of membrane (see 
fig. D) between them. This act of rupturing makes 
no difference in the shape of the rostellum, but con- 
verts the front part into a lip, which can be depressed 
easily. This lip is represented considerably depressed 
in fig. D, and i^s edge is seen, fig. B, in the front view. 
When the lip is thoroughly depressed, the two balls 
of viscid matter are exposed. Owing to the elasticity 
of the hinder part, the lip or pouch, after being 
pressed down, springs up again and encloses the two 
viscid balls. 

I will not affirm that the rupturing of the exterior 
membrane of the rostellum never takes place sponta- 
neously ; and no doubt the membrane is prepared for 
rupture by having become very weak along defined 
lines ; but several times I saw the act ensue from an 
excessively slight touch — so slight that I conclude 
that the action is not simply mechanical, but, for the 
want of a better term, may be called vital. We shall 
hereafter meet with other cases, in which the slightest 



Chap. I. ORCHIS MASCULA. 11 

touch or the vapour of chloroform causes the exterior 
membrane of the rostellum to rupture along certain 
defined lines. 

At the same time that the rostellum becomes trans- 
versely ruptured in front, it probably (for it was 
impossible to ascertain this fact from the position of 
the parts) ruptures behind in two oval lines, thus 
separating and freeing from the rest of the exterior 
surface of the rostellum the two little discs of mem- 
brane, to which the two caudicles are attached exter- 
nally, and to which the two balls of viscid matter 
adhere internally. The line of rupture is thus very 
complex, but strictly defined. 

As the two anther-cells are open longitudinally 
in front from top to bottom, even before the flower 
expands, it follows that as soon as the rostellum is 
properly ruptured from the effects of a slight touch, 
its lip can be depressed easily, and, the two little discs 
of membrane being already separate, the two pollinia 
now lie absolutely free, but are still embedded in their 
proper places. So that the packets of pollen and the 
caudicles still lie within the anther-cells ; the discs 
still form part of the rostellum, but are separate ; and 
the balls of viscid matter still lie concealed within 
the rostellum. 

Now let us see in the case of Orchis maseula (fig. 1) 
how this complex mechanism acts. Suppose an insect 
to alight on the labellum, which forms a good landing- 
place, and to push its head into the chamber (see side 
view, A, or front view, B), at the back of which lies the 
stigma (s), in order to reach with its proboscis the end 
of the nectary ; or, which does equally well to show 
the action, push very gently a sharply-pointed common 
pencil into the nectary. Owing to the pouch-formed 
rostellum projecting into the gangway of the nectary, 



12 OPHRE^. Chap. I. 

it is scarcely possible that any object can be pushed 
into it without the rostellum being touched. The ex- 
terior membrane of the rostellum then ruptures in the 
proper lines, and the lip or pouch is easily depressed. 
When this is effected, one or both of the viscid balls 
will almost infallibly touch the intruding body. So 
viscid are these balls that whatever they touch they 
firmly stick to. Moreover the viscid matter has 
the peculiar chemical quality of setting, like a 
cement, hard and dry in a few minutes' time. As the 
anther-cells are open in front, when the insect with- 
draws its head, or when the pencil is withdrawn, one 
pollinium, or both, will be withdrawn, firmly cemented 
to the object, projecting up like horns, as shown (fig. 2) 

Fiff. 2. 




A. Pollen-mass of 0. mascula, when I B. Pollen-mass of 0. mascula, after 
first attached. | the act of depression. 

by the upper figure, A. The firmness of the attach- 
ment of the cement is very necessary, for if the 
pollinia were to fall sideways or backwards they could 
never fertilise the flower. From the position in 
which the two pollinia lie in their cells, they diverge a 
little when attached to any object. Now suppose that 
the insect flies to another flower, or let us insert the 
pencil (A, fig. 2), with the attached pollinium, into 



CuAP. I. ORCHIS MASCULA. 13 

the same or into another nectary : by looking at the 
diagram (fig. 1, A) it will be evident that the firmly 
attached pollinium will be simply pushed against or 
into its old position, namely, into the anther-cell. 
How then can the flower be fertilised? This is 
effected by a beautiful contrivance : though the viscid 
surface remains immovably affixed, the apparently 
insignificant and minute disc of membrane to which the 
caudicle adheres is endowed with a remarkable power 
of contraction (as will hereafter be more minutely 
described), which causes the pollinium to sweep 
through an angle of about ninety degrees, always in 
one direction, viz., towards the apex of the proboscis or 
pencil, in the course of thirty seconds on an average. 
The position of the pollinium after the movement is 
shown at B in fig. 2. After this movement, completed 
in an interval of time which would allow an insect to 
fly to another plant,* it will be seen, by turning to the 
diagram (fig. 1, A), that, if the pencil be inserted into 
the nectary, the thick end of the pollinium now 
exactly strikes the stigmatic surface. 

Here again comes into play another pretty adapta- 
tion, long ago noticed by Eobert Brown.f The 
stigma is very viscid, but not so viscid as when 
touched by a pollinium to pull the whole off an insect's 
head or off a pencil, yet sufficiently viscid to break 
the elastic threads (fig. 1, F) by which the packets 
of pollen-grains are tied together, and leave some of 
them on the stigma. Hence a pollinium attached to 
an insect or to a pencil can be applied to many 
stigmas, and will fertilise all. I have often seen the 



* Dr. H. Miiller ('Die Befruch- flowers of Orchis mancula, and 

tuns; der Blumen durch lusekten,* finds that this t^tatement is correct. 

IS73, p. 84) has timed humble- f ' Transactions of the Linnean 

bees at work on the spikes of Society,' vol. xvi. p. 731. 



14 OPHEE^. Chap. L 

poUinia of Orchis pjramidalis adhering to the pro- 
boscis of a moth, with the stump-like caudicles alone 
left, all the packets of pollen having been left glued 
to the stigmas of the successively visited flowers. 

One or two other little points must be noticed. 
The balls of viscid matter within the pouch-formed 
rostellum are surrounded with fluid ; and this is 
very important, for, as already mentioned, the viscid 
matter sets hard when exposed to the air for a very 
short time. I have pulled the balls out of their 
pouches, and found that they had entirely lost the 
power of adhesion after a few minutes. Again, the 
little discs of membrane, the movement of which, as 
causing the movement of the poUinia, is so abso- 
lutely indispensable for the fertilisation of the flower, 
lie at the upper and back surface of the rostellum, 
and are closely enfolded and thus kept damp within 
the bases of the anther-cells ; and this is very neces- 
sary, as an exposure of about thirty seconds causes 
the movement of depression to take place ; but as 
long as the disc is kept damp, the pollinia remain 
ready for action whenever removed by an insect. 

Lastly, as I have shown, the pouch, after being 
depressed, springs up to its former position ; and this 
is likewise of great service ; for if this action did not 
take place, and an insect after depressing the lip 
failed to remove the two viscid balls, or if it removed 
one alone, then in the first case both, and in the 
second case one would be left exposed to the air; 
consequently one or both would quickly lose all 
adhesiveness, and the pollinium would be rendered ab- 
solutely useless. That with many kinds of Orchids 
insects often remove only one of the two pollinia at 
a time is certain; it is even probable that they 
generally remove only one, for the lower and older 



Chap. L ORCHIS, 15 

flowers almost always have both poUinia remoyed, 
whilst the younger flowers close beneath the buds, 
which will have been seldomer visited, have frequently 
only one poUinium removed. In a spike of Orchis 
macidata, I found as many as ten flowers, chiefly the 
upper ones, ^\ hich had only one pollinium removed ; 
the other pollinium being still in its proper place with 
the lip of the rostellum well closed up ; so that all the 
mechanism was perfect for its subsequent removal by 
gome other insect. 

When the first edition of this book was published, 
I had not seen any insects visiting the flowers of 
the present species ; but a friend watched some plants, 
•^nd saw them visited by several humble-bees, appa- 
rently Bomhus muscorum ; and Dr. H. Miiller * has seen 
four other species of Bombus at work. He caught 
ninety-seven specimens, and of these thirty-two had 
pollinia attached to their heads. 

The description now given of the action of the 
organs in Orchis mascula applies to 0, morio, fusca, 
macvlata, and latifdia. These species present slight 
and apparently co-ordinated differences in the length 
of their caudicles, in the direction of the nectary, 
in the shape and position of the stigma, but they 
are not worth detailing. In all, the pollinia when 
removed from the anther-cells undergo the curious 
movement of depression, which is so necessary to 
place them in a right position on an insect's head 
for striking the stigmatic surface of another flower. 
Six species of humble-bees, the hive-bee and two 
other kinds have been seen by H. Miiller and myself 
risitiug the flowers of Orchis morio. On some of the 



* ' Die Befruchtung, &c., p. 84. 



16 OPHRE^. Chap. L 

hive -bees from ten to sixteen pollen -masses adhered ; 
to the head of Eucera longicornis eleven, to the head of 
Osmia rufa several, and several to the bare surface close 
above the mandibles of Bomhus muscorum. H. Miiller 
has seen twelve different kinds of bees visiting the 
flowers of 0. latifolia, which are also visited by 
Diptera. My son George observed for some time 
plants of 0. maculata^ and saw many specimens of a 
fly (Empis livida) inserting their proboscides into the 
nectary ; and subsequently the same fact was ob- 
served by me. He brought home six specimens of this 
Empis, with pollinia attached to their spherical eyes, 
on a level with the bases of the antennae. The pollinia 
had undergone the movement of depression, and stood 
a little above and parallel to the proboscis : hence 
they were in a position excellently adapted to strike 
the stigma. Six pollinia were thus attached to one 
specimen, and three to another. My son also saw 
another and smaller species {Empis pennipes) inserting 
its proboscis into the nectary; but this species did 
not act so well or so regularly as the other in 
fertilising the flowers. One specimen of this latter 
Empis had five pollinia, and a second had three 
pollinia, attached to the dorsal surface of its convex 
thorax. H. Miiller has seen two other genera of 
Diptera at work on this orchis, with pollinia attached 
to the front part of their bodies ; and on one occasion 
he saw a humble-bee visiting the flowers.* 

We now come to Orchis (sub-genus, Anacamptis) 
pi/ramidalis, one of the most highly organised species 

* M. M. Girard caught a front of its mouth : 'Aunalea de 

lougicorn beetle, Stranyalia atra, la Soc. Eutomolog. de France,* 

with a tuft of the pollen-masses torn ix. 1869, p. xxxi. 
of this orchis attached to the 



Chap. I. OECHIS PYEAMIDALIS. 17 

which I have examined, and which is ranked by several 
botanists as a distinct genus. The relative position of 
the parts (fig. 3) is here considerably different from 
what it is in 0. mascula and its allies. There are two 
quite distinct rounded stigmatic surfaces (s, s, A) 
placed on each side of the pouch-formed rostellum. 
This latter organ, instead of standing some height 
above the nectary, is brought down (see side view B) 
so as to overhang and partially to close its orifice. 
The ante-chamber to the nectary, formed by the 
union of the edges of the labellum to the column, 
which is large in 0. mascula and its allies, is here 
small. The pouch-formed rostellum is hollowed out 
on the under side in the middle : it is filled with 
fluid. The viscid disc is single and of the shape of a 
saddle (figs. C and E) ; it carries on its nearly flat 
top or seat the two caudicles of the pollinia, the ends 
of which firmly adhere to its upper surface. Befor« 
the membrane of the rostellum ruptures, the saddle- 
formed disc can be clearly seen to ba continuous with 
the rest of the surface. The disc i:^ partially hidden 
and kept damp (which is of great importance) by the 
over-folding bases of the two anther-cells. It consists 
of several layers of minute cells, and is therefore rather 
thick ; it is lined beneath with a layer of highly ad- 
hesive matter, which is formed within the rostellum. 
It corresponds strictly to the two minute, oval, sepa- 
rate discs to which the two caudicles of 0. mascula 
and its allies are attached. 

When the flower opens and the rostellum has 
become symmetrically ruptured, either from a touch 
or spontaneously (I know not which), the slightest 
pressure depresses the lip, that is, the lower and bi- 
lobed portion of the exterior membrane of the ros- 
tellum, which projects into the mouth of the nectary. 



18 



OPHEE.E. 



Chap. I. 



Fig. 3. 




Orchis pyrajiidalis. 



Obap. L OECHIS PYEAMIDALIS. 19 



Description of Ym. 8. 

«, anther. ^- labellum. 

s,s. stigma. ^'. guiding plate on the labellum. 

r. rostellum. n. nectary. 

A. Front view, with all the sepals and petals removed, except the 

labellum. 

B. Side view, with all the sepals and petals removed, with the labellum 

longitudinally bisected, and with the near side of the upper part 
of the nectary cut away. 

C. The two pollinia attached to the saddle-shaped viscid disc. 

D. The disc after the first act of contraction, with no object seized. 

E. The disc seen from above, and flattened by force, with one polliniura 

removed; showing a depression in its surface, by which the second 
movement of the pollinium is effected. 

F. The pollinia removed by the insertion of a needle into the nectary, after 

the saddle has clasped the needle by the first act of contraction. 
O. The same pollinia after the second movement and their consequent 
depression. 



20 OPHEE^. Chap. 1. 

When the lip is depressed, the under and viscid surface 
of the disc, still remaining in its proper place, is un- 
covered, and is almost certain to adhere to the touch- 
ing object. Even a human hair, when pushed into 
the nectary, is stiff enough to depress the lip or 
pouch ; and the viscid surface of the saddle adheres 
to it. If, however, the lip be pushed only slightly, 
it springs back and recovers the under side of the 
saddle. 

The perfect adaptation of the parts is well shown by 
cutting off the end of the nectary and inserting a 
bristle at that end ; consequently in a reversed direc- 
tion to that in which moths insert their proboscides ; 
and it will be found that the rostellum may easily be 
torn or penetrated, but that the saddle is rarely or 
never caught. When the saddle together with the 
pollinia is removed on a bristle, the under lip in- 
stantly curls closely inwards, and leaves the orifice of 
the nectary more open than it was before ; but whether 
this is of much service to the moths which frequent 
the flowers, and consequently to the plant, I will nol! 
pretend to decide. 

Lastly, the labellum is furnished with two pro- 
minent ridges (/', figs. A, B), sloping down to the 
middle and expanding outwards like the mouth of a 
decoy ; these ridges serve to guide any flexible 
body, like a fine bristle or hair, into the minute and 
rounded orifice of the nectary, which, small as it 
already is, is partly choked up by the rostellum. 
This contrivance of the guiding ridges may be com- 
pared to the little instrument sometimes used for 
guiding a thread into the fine eye of a needle. 

Now let us see how these parts act. I^et a moth 
insert its proboscis (and we shall presently see how 
frequently the flowers are visited by Lepidoptera) 



Chap. I. ORCHIS PYRAMIDALIS. 21 

between the guiding ridges of the labellum, or iusert 
a fine bristle, and it is conducted safely to the minute 
orifice of the nectary, and can hardly fail to depress 
the lip of the rostellum ; this being effected, the 
bristle comes into contact with the now naked and 
sticky under surface of the suspended saddle-formed 
disc. When the bristle is removed, the saddle with 
the attached pollinia is removed. Almost instantly, 
as soon as the saddle is exposed to the air, a rapid 
movement takes place, and the two flaps curl inwards 
and embrace the bristle. When the pollinia are 
pulled out by their caudicles, by a pair of pincers, 
so that the saddle has nothing to clasp, I observed 
that the flaps curled inwards so as to touch each 
other in nine seconds (see fig. D), and in nine more 
seconds the saddle was converted by the flaps curl- 
ing still more inwards into an apparently solid ball. 
The proboscides of the many moths which I have 
examined, with the pollinia of this Orchis attached 
to them, were so thin that the tips of the flaps just 
met on the under side. Hence a naturalist, who 
sent me a moth with several saddles attached to its 
proboscis, and who did not know of this movement, 
very naturally came to the extraordinary conclusion 
that the moth had cleverly bored through the exact 
centres of the so-called sticky glands of some 
Orchid. 

Of course this rapid clasping movement helps to fix 
the saddle upright on the proboscis, which is very 
important ; but the viscid matter setting hard raj)idly 
would probably suffice for this end, and the real object 
gainf^d by the clasping or curling movement is the 
divergence of the pollinia. The pollinia, being at- 
tached to the flat top or seat of the saddle, project at 
first straight up and nearly parallel to each other ; 



22 OPHllE.^. Chap. I. 

but as the flat top curls round the cylindrical and 
thin proboscis, or round a bristle, the pollinia neces- 
sarily diverge. As soon as the saddle has clasped the 
bristle and the pollinia have diverged, a second move- 
ment commences, which action, like the last, is ex- 
clusively due to the contraction of the saddle-shaped 
disc of membrane, as will be more fully described in 
the ninth chapter. This second movement is the 
same as that in 0. mascula and its allies, and causes 
the divergent pollinia, which at first projected at right 
angles to the needle or bristle (see fig. F), to sweep 
through an angle of nearly ninety degrees towards the 
tip of the needle (see fig. G), so as to become de- 
pressed and finally to lie in the same plane with the 
needle. In three specimens, this second movement 
was effected in from thirty to thirty -four seconds after 
the removal of the pollinia from the anther-cells, and 
therefore in about fifteen seconds after the saddle had 
clasped the bristle. 

The use of this double movement becomes evident 
if a bristle with pollinia attached to it, which have 
diverged and become depressed, be pushed between 
the guiding ridges of the labellum into the nectary 
of the same or another flower (compare figs. A and 
G) ; for the two ends of the pollen-masses will be 
found now to have acquired such a position that the 
end of the one strikes against the stigma on the one 
side, and the end of the other at the same moment 
strikes against the stigma on the opposite side. The 
secretion on the stigmas is so viscid that when the 
pollinia are withdrawn, the elastic threads by which 
the packets of pollen are bound together are ruptured ; 
and some dark-green grains may be seen, even by the 
naked eye, remaining on the two white stigmatic sur- 
faces. I have shown this little experiment to several 



Chap. I. ORCHIS PYEAMIDALIS. 23 

persons, and all have expressed the liveliest admiration 
at the perfection of the contrivance by which this 
Orchid is fertilised. 

As in no other plant, or indeed in hardly any 
animal, can adaptations of one part to another, and 
of the whole to other organisms widely remote in the 
scale of nature, be named more perfect than those 
presented by this Orchis, it may be w^orth while 
briefly to sum them up. As the flowers are visited 
both by day and night-flying Lepidoptera, it is not 
fanciful to believe that the bright-purple tint (whether 
or not specially developed for this purpose) attracts 
the day-fliers, and the strong foxy odour the night- 
fliers. The upper sepal and two upper petals form a 
hood protecting the anther and stigmatic surfaces 
from the weather. The labellum is developed into a 
long nectary in order to attract Lepidoptera, and we 
shall presently give reasons for suspecting that the 
nectar is purposely so lodged that it can be sucked 
only slowly (very differently from what occurs in most 
other plants), in order to give time for the viscid 
matter on the under side of the saddle to set hard 
and dry. He who will insert a fine and flexible 
bristle into the expanded mouth of the flower between 
the sloping ridges on the labellum, will not doubt 
that they serve as guides and effectually prevent the 
bristle or proboscis from being inserted obliquely into 
the nectary. This latter circumstance is of manifest 
importance, for, if the proboscis were inserted ob- 
liquely, the saddle-formed disc would become attached 
obliquely, and after the compounded movement of the 
pollinia they would not strike the two lateral stigmatic 
surfaces. 

Then we have the rostellum partially closing the 
mouth of the nectary, like a trap placed in a run for 



24 OPHREiE. Chap. L 

game ; and the trap so complex and perfect, with its 
symmetrical lines of rnptnre forming the saddle- 
shaped disc above, and the lip of the pouch below ; 
and, lastly, this lip so easily depressed that the pro- 
boscis of a moth can hardly fail to uncover the viscid 
disc and adhere to it. But if this fails to occur, the 
elastic lip rises and covers again the viscid surface, 
so as to keep it damp. The viscid matter within the 
rostellum is attached to the saddle-shaped disc alone, 
and is surrounded by fluid, so that it does not set hard 
till the disc is withdrawn. The upper surface of the 
saddle, with the attached caudicles, is also kept 
damp by the bases of the anther-cells, until it is 
withdrawn, and then the curious clasping movement 
instantly commences, causing the pollinia to diverge, 
followed by the movement of depression, which move- 
ments together are exactly fitted to cause the ends 
of the two pollen-masses to strike the two stigmatic 
surfaces. These stigmatic surfaces are not so sticky 
as to tear off the whole poUinium from the proboscis 
of the moth, but by rupturing the elastic threads to 
secure a few packets of pollen, leaving plenty for other 
flowers.* 

But let it be observed that, although the moth pro- 
bably takes a considerable time to suck the nectar of 
a flower, yet the movement of depression in the pol- 
linia does not commence (as I know by trial) until 
they are fully withdrawn ; nor will the movement be 
completed, and the pollinia properly placed for strik- 
ing the stigmatic surfaces, until about half a minute 
has elapsed, which will give ample time for the moth to 



* The late Prof. Treviranus has bnt points out two unimportant 
confirmed (' Botanische Zeitung,' inaccuracies in the drawing which 
1863, p. 241) all my observations, I have given. 



Chap. I ORCHIS USTULATA. 25 

fly to another plant, and thus effect a union between 
two distinct individuals. 

Orchis ustulata * resembles 0. pyramidalis in some 
important respects, and differs from it in others. The 
labellum is deeply channelled, and the channel which 
replaces the guiding ridges of 0. pi/ramidalifi leads to 
the small triangular orifice of the short nectary. The 
upper angle of the triangle is overhung by the ros- 
tellumj the pouch of which is rather pointed below. 
In accordance with this position of the rostellum, 
close to the mouth of the nectary, the stigma is 
double and lateral. This species shows in an interest- 
ing manner how easily two distinct stigmas, like those 
of 0. pyramidalis, might be converted into a single 
one, by becoming at first slightly lobed like that of 
0. masGula, and then acquiring its present structure. 
For directly beneath the rostellum there is a narrow 
transverse rim, formed of true stigmatic tissue, which 
connects together the two lateral stigmas ; so that 
if this rim were widened, the tv>'o stigmas would be 
converted into a single transverse one. Conversely 
a single stigma might thus easily be converted into a 
double one. The pollinia undergo the usual move- 
ment of depression, and in acquiring this position 
the two diverge slightly, so as to be ready to strike the 
two lateral stigmas. 

Orchis (sub-genus Ilimantoglossum) hircina. — A fine 
specimen of this extremely rare British plant, the 
Lizard Orchis, with its curious elongated labellum, 
was sent me by Mr. Oxenden. The two pollinia 
arise from a single almost square disc ; and when 



* I am greatly indebted to IMr. kindness in supplying me with 
G. Chichester Oxenden of Broome living plants, and information re- 
Park fur frtsh specimens of this gaiding many of the rarer Britisn 
Orchis, and for his never-tiring Orchids. 



26 CPHRE^. Chap. L 

they are removed from their cells, they do not di- 
verge, but become depressed, sweeping through an 
angle of ninety degrees, in about thirty seconds. They 
are then in a proper position for striking the single 
large stigma which lies beneath the rostellum. In the 
case of 0. pjramidalis we have seen that the depression 
of the two poUinia is effected by the contraction of 
the disc in front of each, two furrows or valleys being 
there formed ; whilst with the present species, the 
whole front of the disc contracts or sinks down, the 
iront part being thus separated from the hinder part 
by an abrupt step. 

Acer as* {Orchis) antliropoiohora. — The caudicles of 
the pollinia are unusually short ; the nectary consists 
of two minute rounded depressions in the labellum; 
the stigma is transversely elongated; and lastly the 
two viscid discs lie so close together within the ros- 
tellum that they affect each other's outline. This 
latter fact is worth notice, as a step towards the two 
becoming absolutely confluent, as in the following 
species of Aceras, in 0. 'pyramidalis and hircina. 
Nevertheless, in Aceras a single pollinium is some- 
times removed by insects, though more rarely than 
with the other species of Orchis. 

Aceras {Orchis) longibracteata, — Mr. Moggridge has 
given an interesting account, together with a figure, 
of this plant which grows in the South of France.f 
The pollinia are attached to a single viscid disc. 
When they are removed they do not diverge as in 
0, pyramidalis, but converge and then undergo the 



* The separation of this genus occurrence of numerous hybrids, 

is evidently artificial. It is a true naturally produced, between this 

Orchis, but witli a very short At-eras and Orchis galeata. 

nectary. Dr. Weddell has de- t ' Journ. Linn. See. Bot.* 

scribed (' Annales des Sc. Nat.,* vol. viii. 1865, p. 256. He gives 

3 ser. Bot. torn, xviii. p. 6) the also a figure of Orchis hircina. 



CHAr. I. NIGRITELLA ANGUSTIFOLIA. 27 

movement of depression. The most remarkable point 
about this species is that insects seem to suck nectar 
out of minute open cells in the honeycombed surface 
of the labellum. The flowers are visited by various 
hymenopterous and dipterous insects ; and the author 
saw the pollinia attached to the forehead of a large 
bee, the Xylocopa viola cea. 

Neotinea {Orchis) intada. — Mr. Moggridge sent me 
from North Italy living specimens of this very rare 
British plant, which, as he informed me, is remark- 
able from producing seeds without the aid of insects. 
When insects were carefully excluded by me, almost 
all the flowers produced capsules. Their fertilisation 
follows from the pollen being extremely incoherent, so 
as to fall spontaneously on the stigma. Nevertheless 
a short nectary is present, the pollinia possess small 
viscid discs, and all the parts are so arranged that, 
if insects were to visit the flowers, the pollen-masses 
would almost certainly be removed and carried to 
another flower, but not so effectually as with most 
other orchids. 

Serapias cordigera, an inhabitant of the South of 
France, has been described by Mr. Moggridge in the 
paper just referred to. The pollinia are attached to 
a single viscid disc ; when first withdrawn, they are 
bent backwards, but soon afterwards move forwards 
and downwards in the usual manner. As the stigmatic 
cavity is narrow, the pollinia are guided into it by two 
guiding plates. 

Nigritella angustifolia. — This Alpine species is said 
by Dr. H. Miiller * to differ from all ordinary orchids 
in the ovarium not being twisted ; so that the labellum 
stands on the upper side of the flower, and insects 



Nature,' Dec. 31, 1874, p. 169. 



28 OPHRE^. Chap. I. 

alight on the opposite sepals and petals. As a con- 
sequence of this, when a butterfly inserts its proboscis 
into the narrow entrance of the nectary, the yiscid discs 
become attached to the lower surface of the proboscis, 
and the pollinia afterwards move upwards, instead of 
as in all other orchids downwards. They are then in 
the proper position for striking the stigma of the next 
flower which is visited. Dr. Miiller remarks that the 
flowers are frequented by an extraordinary number of 
butterflies. 

I have now described the structure of most of the 
British and of a few foreign species in the genus 
Orchis and its close allies. All these species, with the 
exception of the Neotinea, require the aid of insects for 
their fertilisation. This is obvious from the fact that 
the pollinia are so closely embedded in the anther-cells, 
and the ball of viscid matter in the pouch-formed 
rostellum, that they cannot be shaken out by violence. 
We have also seen that the pollinia do not assume the 
proper position for striking the stigmatio surface until 
some time has elapsed; and this indicates that they 
are adapted to fertilise, not their own flow^ers, but those 
on a distinct plant. To prove that insects are neces- 
sary for the fertilisation of the flowers, I covered up 
a plant of Orchis morio under a bell-glass, before 
any of its pollinia had been removed, leaving three 
adjoining plants uncovered ; 1 looked at the latter 
every morning, and daily found some of the pollinia 
removed, till all were gone with the exception of those 
in a single flower low down on one spike, and of those 
in one or two flowers on the summits of all the spikes, 
which were never removed. But it should be observed 
that when only a very few flowers remain open on the 
summits of the spikes, these are no longer conspicuous. 



Chap. I. FERTILISED BY INSECTS. 29 

and would consequently be rarely visited by insects. 
I then looked at the perfectly healthy plant under 
the bell-glass, and it had, of course, all its pollinia in 
the anther-cells. I tried an analogous experiment with 
specimens of 0. mascula with the same result. It de- 
serves notice that the spikes which had been covered 
up, when subsequently left uncovered, never had their 
pollinia carried away by insects, and did not, of course, 
set any seed, whereas the adjoining plants produced 
plenty of seed. From this fact it may be inferred 
that there is a proper season for each kind of Orchis, 
and that insects cease their visits after the proper 
season has passed. 

With many of the hitherto mentioned species, and 
with several other European kinds, the sterility of the 
flowers, when protected from the access of insects, 
depends solely on the pollen-masses not coming into 
contact with the stigma. This has been proved to be 
the case by Dr. Hermann Miiller, who, as he informs 
me, applied the pollen-masses of Orchis pjramidalis 
(44), fasca (6), militaris (14), variegata (3), coriopJiora 
(6), morio (4), maculata (18), mascula (6), latifolia (8), 
incarnata (3), Oplirys muscifera (8), Gymnadenia conop- 
sea (14), alhida (8), Serminium monorcliis (6), Epipogon 
aphijllus (2), Epipactis laiifoUa (14:),palustris (4), Listera 
ovata (5), and Cypripedmm calceolus (2), to their own 
stigmas, and full-sized capsules, containing seeds in 
appearance good, were formed. The numbers placed 
after the names of the species show how many flowers 
were tried in each case. These facts are remarkable, 
because Mr. Scott and Fritz Miiller* have proved 



♦ An abstract of their observa- ticaiion,' chap. xvii. 2ud edit, vol 
tions is given in my 'Variation of ii. p. 114. 
Animals and Plants under Domes- 



30 OPHREJE. CiiAP. 1. 

that various exotic species, both in this country and 
in their native homes, invariably fail to yield seed- 
capsules, when the flowers are fertilised with their own 
pollen. 

From the observations already given, and from 
what will hereafter be shown with respect to Gym 
nadenia, Habenaria, and some other species, it is a 
safe generalisation* that species with a short and 
not very narrow nectary are fertilised by beesf and 
flies; whilst those with a much elongated nectary, 
or one having a very narrow entrance, are fertilised 
by butterflies or moths, these being provided with 
long and thin proboscides. We thus see that the 
structure of the flowers of Orchids and that of 
the insects which habitually visit them, are corre- 
lated in an interesting manner, — a fact which has 
been amply proved by Dr. H. Miiller to hold good 
with many of the Orchidese and other kinds of 
plants. 

With respect to Orchis pyramidalis, which possesses, 
as we have seen, an elongated nectary, Mr. Bond was 
so kind as to send me a large number of Lepidoptera, 
out of which I selected twenty-three species, enumer- 
ated in the following list, with the poUinia of this 
Orchid, which can easily be recognised, attached to 
their proboscides. 

* Some remarks to this effect near the Jardin de la Faculte (at 

were given in my "Notes on Toulouse?) complained tliat his 

the Fertilisation of Orchids," in bees retivned from the garden 

' Annals and Mag. of Nat. Hist.' with their hetcls charged witL 

Sept. 1869, p. 2. yellow bodies, of which tiiey could 

t M. Me'niere (in 'Bull. Bot. not free themselves. This is good 

Soc. de Friiuce,' torn. i. 1854, p. evidence how firmly the poliiuia 

370) says he saw in Dr. Gue'pin's are attached. There is, however, 

collection, bees collected at San- nothing to show whether the pol- 

mur with the poUinia of Orchids linia in these cases belonged to 

attached to their heads ; and he the genus Orchis or to some other 

states that a person who kept bees genus of the family. 



Cjiai'. 1. 



FERTILISED BY INSECTS. 



31 



Polyommatus alexia. 
Lycsena phlseas. 
Arge galathea. 
Hesperia sylvanus. 

„ linea. 
Syrichthus alveolus. 
Anthrocera filipendulse. 

„ trifolii.* 

Lithosia complana. 
Leucania lithargyria (two speci- 
mens). 
Caradiina blanda. 
„ al sines, 
Agrotis cataleuca. 



Eubolia mensuraria (two speci- 
mens). 

Hadena dentina. 

Heliothis marginata (two speci- 
mens). 

Xylophasia sublustris (two speci- 
mens). 

Euclidia glyphica. 

Toxoeampa pastinum. 

Melauippe rivaria. 

Spilodes palealis. 
„ cinctalis. 

Acontia luctuosa. 



A large majority of these moths and butterflies 
had two or three pairs of pollinia attached to them, 
and invariably to the proboscis. The Acontia had 
seven pair (fig. 4), and the Fig. 4. 

Caradrina no less than eleven 
pair ! The proboscis of this 
latter moth presented an ex- 
traordinary arborescent ap- 
pearance. The saddle-formed 
discs, each bearing a pair of 
pollinia, adhered to the pro- 
boscis, one before the other, 

witn perfect symmetry ; and Head and proboscis of Acontia luc- 
., . p n o ,T ., tuosn with seven pair of oollinia 

this lolloWS Irom the moth of Orchis pyramidalis attached 

having always inserted its ^° ^^^ proboscis. 
proboscis into the nectary in exactly the same manner, 
owing to the presence of the guiding plates on the 
labellum. The unfortunate Caradrina, with its pro- 
boscis thus encumbered, could hardly have reached 
the extremity of the nectary, and would soon have 




♦ I am imlebted to Mr. Parfitt 
for an examination of tliis moth, 
wliich is mentioned in the ' En- 
toniologifct's Weekly Intelligencer,' 
vol. ii. p. 182, and vol. iii. p. 3, 
Oct. 3, 1857. The pollinia were 



erroneously thought to belong to 
Ophrys apifera. The pollen had 
changed from its natural green 
colour to yellow : on wasliing it, 
however, and drying it, the green 
tint returned. 



32 OFHEE^. Chap. I. 

been starved to death. Both these moths must have 
sucked many more than the seven and eleven flowers, 
of which they bore the trophies, for the earlier at- 
tached pollinia had lost much of their pollen, showing 
that they had touched many viscid stigmas. 

The above list proves that many different species 
of Lepidoptera visit the same kind of Orchis. The 
Hadena dentina also frequents Habenaria. Probably 
all the Orchids provided with elongated nectaries 
are visited indifferently by many kinds of moths. 
Whether any of the British Orchids are fertilised 
exclusively by special insects confined to certain 
localities is very doubtful ; but we shall hereafter see 
that Epipadis latifoUa seems to be fertilised by wasps 
alone. I have twice observed plants of Gymnadenia 
conopea, which had been transplanted into a garden 
many miles from its native home, with nearly all 
their pollinia removed. Mr. Marshall of Ely* has 
made the same observation on similarly transplanted 
specimens of 0. macuJata. On the other hand fifteen 
plants of Ophrtjs muscifera had not one pollen-mass 
there removed. Malaxis paludosa was placed in a 
bog about two miles from that in which it naturally 
grew ; and it had most of its pollinia immediately 

removed. 

The list which follows serves to show that insects m 
most cases perform the work of fertilisation effectually. 
But the list by no means gives a fair idea how effectu- 
ally it is done ; for I have often found nearly all the 
pollinia removed, but kept an exact record only in 
exceptional cases, as may be seen by the appended 
remarks. Moreover, in most cases, the pollmia which 

» ' Gardener's Chronicle,' 1861, marks of mine on this subject 
n 73. Mr. Marshall's communi- previouslpublished m the Gar- 
cat on was in answer to some re- dener's Chronicle, lb60, p. 528. 



Chav. I. 



FERTILISED BY INSECTS. 



33 



had not been removed were in the upper flowers 
beneath the buds, and many of these would probably 
have been subsequently carried away. I have often 
found an abundance of pollen on the stigmas of flowers 
which had not their own pollinia removed, showing 
that they had been visited by insects. In many other 
cases the pollinia had been removed, but no pollen had 
been as vet left on the stigmas. 



Orchis morio. Three small plants. N.| 
Kent / 

Orchis morio. Thirty-eight plants. N.^ 
Kent. These plants were examined 
after nearly four weeks of extraordi- 
narily cold and wet weather in 1860 ; 
and therefore under the most unfavour- 
able circumstances 

Orchis pyramidalis. Two plants. N.| 
Kent and Devonshire. . . ./ 

Orchis pyramidalis. Six plants from two"! 
protected valleys. Devonshire . . / 

Orchis pyramidalis. Six plants from al 
much exposed bank. Devonshire . j 

Orchis maculata. One plant. Stafford-i 
shire. Of the twelve flowers which had] 
not their pollinia removed, the greater!- 
number were young flowers under the 
buds ..... .J 

Orchis maculata. One plant. Surrey . 

Orcliis maculata. Two plants. N. and) 
S.Kent / 

Orchis latifolia. Nine plants from S. 
Kent, sent me by the Rev. B. S. Maiden. 
Tl-.e flowers were all mature 

Orchis fusca. Two plants. S. Kent.l 
Flowers quite mafure, and even withered/ 

Aceras anlhropoi)hora. Four plants. S.' 
Kent ..... 



':} 






£5 



22 
110 

39 

102 
57 

32 

21 

28 

50 

8 
63 



5 o 



s .:; tn .= i 



2 c ® 2 o 

3 a 3 05 o 



23 



5 

17 

27 

5 
6 






193 



G6 

166 

12 

7 
50 

119 

54 
34 



34 OFHEE^. Chap. I. 

In the second lot of 0. morio, in the preceding list, 
we see the injurious effects of the extraordinary cold 
and wet season of 1860 on the visits of insects, and, 
consequently, on the fertilisation of this Orchid, very 
few seed-capsules having been produced. 

I have examined spikes of 0. pi/ramidalis in which 
every single expanded flower had its poUinia removed. 
The forty-nine lower flowers of a spike from Folkestone 
(sent me by Sir Charles Lyell) actually produced forty- 
eight fine seed-capsules ; and of the sixty-nine lower 
flowers in three other spikes, seven alone had failed to 
produce capsules. These facts show how well moths 
and butterflies perform their office of marriage-priests.* 

The third lot of 0. pjrainidalis in the above list 
grew on a steep grassy bank, overhanging the sea near 
Torquay, and where there were no bushes or other 
shelter for Lepidoptera ; being surprised how few pol- 
linia had been removed, though the spikes were old 
and very many of the lower flowers withered, I gathered, 
for comparison, six other spikes from two bushy and 
sheltered valleys, half a mile on each side of the 
exposed bank ; these spikes were certainly younger, 
and would probably have had several more of their 
pollinia removed ; but in their present condition we 
see how much more frequently they had been visited by 
moths, and consequently fertilised, than those growing 
on the much exposed bank. The Bee Ophrys and 
0. pjramidalis grow mingled together in many parts 
of England ; and they did so here, but the Bee Oj)hrys, 
instead of being, as usual, the rarer species, was here 



♦ In the summer of 1875, whicli ing fertilised ; and on tliis occasion 
was a very wet one, I gatliered six only 119 flowers produced cap- 
unusually fine spikes of 0. pyra- sules, 183 Laving faiUd to do so. 
midulis. Tliese bore 302 flowers. Six sjakes of O. maculata bore 187 
excluding fourteenwliich were still flowers, of which eighty-two pro- 
fuliy expanded and capable of be- duced capsules, 105 having failed. 



Chap. I. FERTILISED BY INSECTS. 35 

raucli more abundant than 0. pyramidalis. !No one 
would readily have suspected that one chief reason of 
this difference probably was, that the exposed situation 
was unfayourable to Lepidoptera, and therefore to the 
seeding of 0. 'pijramiclalis ; whereas, as we shall here- 
after see, the Bee Ophrys is independent of insects. 

Many spikes of 0. latifoUa were examined, because, 
being familiar with the usual state of the closely-allied 
0. maculata, I was surprised to find in nine nearly 
withered spikes (as may be seen in the list) how few 
pollinia had been removed. In one instance, however, 
0. maculata had been even worse fertilised ; for seven 
spikes with 315 flowers, produced only forty-nine seed- 
capsules — that is, on an average only seven capsules 
on each spike. In this case the plants formed larger 
beds than I had ever before seen ; and I imagine that 
there were too many flowers for the insects to visit 
and fertilise all of them. On some other plants of 
0. maculata growing at no great distance, above thirty 
capsules had been produced by each spike. 

Orchis fusca offers a still more curious case of 
imperfect fertilisation. I examined ten fine spikes 
from two localities in South Kent, sent to me by Mr. 
Oxenden and Mr. Maiden : most of the flowers on these 
spikes were partly withered, with the pollen mouldy 
even in the uppermost flowers ; we may therefore infer 
that no more pollinia would have been removed. I 
examined all the flowers only in two spikes, on account 
of the trouble from their withered condition, and the 
result may be seen in the list, namely, fifty-four 
flowers with both pollinia in place, and only eight 
with one or both removed. In this Orchid, and in 0. 
latifoUa, neither of which had been sufficiently visited 
by insects, there were more flowers with one pollinium 
than with both removed. I casually examined many 



36 OPHKE^. Chap. I. 

flowers in the other spites of 0. fusca, and the propor- 
tion of pollinia removed was evidently not greater 
than in the two in the list. The ten spikes bore 
altogether 358 flowers, and, in accordance with the 
few pollinia removed, only eleven capsules had been 
formed : five of the ten spikes produced not a single 
capsule ; two spikes had only one, and one had as 
many as four capsules. As corroborating what I have 
before said with respect to pollen being often found on 
the stigmas of flowers which retain their own pollinia, 
I may add that, »of the eleven flowers which had 
produced capsules, five had both pollinia still within 
their now withered anther-cells. 

From these facts the suspicion naturally arises that 
0. fusca is so rare a species in Britain from not being 
sufliciently attractive to insects, and to its not 
producing a sufficiency of seed. C. K. Sprengel* 
noticed, that in Germany 0. militaris (ranked by 
Bentham as the same species with 0. fusea) is likewise 
imperfectly fertilised, but more perfectly than our 0. 
fusca ; for he found five old spikes bearing 138 flowers 
which had set thirty-one capsules ; and he contrasts the 
state of these flowers with those of Gymnadenia conop- 
sea, in which almost every flower produces a capsule. 

An allied and curious subject remains to be discussed. 
The existence of a well-developed spur-like nectary 
seems to imply the secretion of nectar. But Sprengel, 
a most careful observer, thoroughly searched many 
flowers of 0. latifolia and morio, and could never find 
a drop of neclar; nor could Kriinitzt find nectar 



* 'Das entdeckte Geheimniss/ tung der Nektarien,' 1S33, s. 28. 

etc. s. 404. See also ' Das entdeckte Geheim- 

t Quoted by J. G. Kurr in his niss,' s. 403. 
^Untersuehungen iibor 'lie Bedeu- 



Chap. I. SECRETION OF NECTAR. 37 

either in the nectary or on the hibellum of 0. morio, 
fusca, 7nilitaris, maculata or latifolia. I have looked 
to all our common British species and could find no 
trace of nectar; I examined, for instance, eleven 
flowers of 0. maculata^ taken from different plants 
growing in different districts, and taken from the most 
favourable position on each spike, and could not find 
under the microscope the smallest bead of nectar. 
Sprengel calls these flowers " Scheinsaftblumen" or 
sham-nectar-producers ; — he believes that these plants 
exist by an organized system of deception, for he well 
knew that the visits of insects were indispensable for 
their fertilisation. But when we reflect on the incalcul- 
able number of plants which have lived during a great 
length of time, all requiring that insects should carry 
the pollen-masses from flower to flower in each gene- 
ration ; and as we further know from the number of the 
pollen-masses attached to their proboscides, that the 
same insects visit a large number of flowers, we can 
hardly believe in so gigantic an imposture. He 
who believes in Sprengel's doctrine must rank the 
sense or instinctive knowledge of many kinds of 
insects, even bees, very low in the scale. To test 
the intellect of moths and butterflies I tried the 
following little experiment, which ought to have been 
tried on a larger scale. I removed a few already- 
opened flowers on a spike of 0. pjramiclalis, and 
then cut off about half the length of the nectaries 
of the six next non-expanded flowers. When all the 
flowers were nearly withered, I found that thirteen 
of the fifteen upper flowers with perfect nectaries 
had their pollinia removed, and two alone had their 
pollinia still in the anther-cells ; of the six flowers 
with their nectaries cut off, three had their pollinia 
removed, and three were still in place ; and this in- 



38 OPHRE^. Chap. I. 

dicates that moths do not go to work in a quite sense- 
less manner.* 

Nature may be said to have tried this same experi- 
ment, but not quite fairly; for Orchis pyramidalis, 
as shown by Mr. Bentham,t often produces monstrous 
flowers without a nectary, or with a short and imperfect 
one. Sir C. Lyell sent me several spikes from Folke- 
stone with many flowers in this condition : I found six 
without a vestige of a nectary, and their pollinia had 
not been removed. In about a dozen other flowers, 
having either short nectaries, or with the labellum 
imperfect, the guiding ridges being either absent or 
developed in excess and rendered foliaceous, the 
pollinia in one alone had been removed, and the ova- 
rium of another flower was swelling. Yet I found 
that the saddle-formed discs in these eighteen flowers 
were perfect, and that they readily clasped a needle 
when inserted in the proper place. Moths had removed 
the pollinia, and had thoroughly fertilised the perfect 
flowers on the same spikes ; so that they must have 
neglected the monstrous flowers, or, if visiting them, 
the derangement in the complex mechanism of the 
parts had hindered the removement of the pollinia, 
and prevented their fertilisation. 

Notwithstanding these several facts I still suspected 
that nectar must be secreted by our common Orchids, 



* Kurr (' Beilcutung der Nek- the corolla, leaving the nectary, of 

tarien,' 1833, p 123) cut off the forty flowers of Orchis morio, and 

nectaries of fifteen flowers of tliese set no capsules; and this 

Gymnarhnia comqjsea, and tliey case shows that insects are guided 

did not produce a single capsule : to the flowers by the corolla, 

he also tnated in the same man- Sixteen flowers of Platanthera 

ner fifteen flowers of Platanthera treated in tlie same manner bore 

or Hahenaria hifoUa, and these only one capsule. Similar experi- 

set only five capsules; but then it ments made by him on Gymna- 

should be observed that the nee- denia seem to me open to doubt, 
taries of both these orchids con- t 'Handbook of the British 

tain free nectar. He also cut off Flora,' 1858, p. 501. 



Chap. I. SECRETION OF NECTAR. 39 

and I determined to examine 0. morio rigorously. As 
soon as many flowers were open, I began to examine 
them for twenty-three consecutive days : I looked at 
them after hot sunshine, after rain, and at all hours : 
I kept the spikes in water, and examined them at 
midnight, and early the next morning: I irritated 
the nectaries with a bristle, and exposed them to 
irritating vapours : I took flow^ers which had lately had 
their pollinia removed by insects, of which fact I had 
independent proof on one occasion by finding grains 
of some foreign pollen within the nectary ; and 1 took 
other flowers, which judging from their position on the 
spike, would soon have had their pollinia removed ; 
but the nectary was invariably quite dry. After the 
publication of the first edition of this work, I one 
day saw various kinds of bees visiting repeatedly the 
flowers of this same Orchid, so that this w^as evidently 
the proper time to examine their nectaries ; but I failed 
to detect under the microscope even the minutest drop 
of nectar. So it was with the nectaries of 0. maculata 
at a time when I repeatedly saw flies of the genus 
Empis keeping their proboscides inserted into them 
for a considerable length of time. Orchis pjramidalis 
was examined with equal care with the same result, 
for the glittering points within the nectary were abso- 
lutely dry. AVe may therefore safely conclude that 
the nectaries of the above-named Orchids neither in 
this country nor in Germany ever contain nectar. 

Whilst examining the nectaries of 0. morio and 
maculata^ and especially of 0. pyramidalis and hircina^ 
I was surprised at the degree to which the inner and 
outer membranes forming the tube or spur were sepa- 
rated from each other, — also at the delicate nature of 
the inner membrane, which could be penetrated very 
easily, — and, lastly, at the quantity of fluid contained 



40 OrnEE^. Chap. L 

between the two membranes. So copious is this fluid, 
that, after cutting off the extremities of the nectaries 
of 0. 2'>ijycimidalis^ and gently squeezing them on glass 
under the microscope, such large drops of fluid exuded 
from the cut ends, that I concluded that at last I had 
found nectaries which contained nectar; but when I care- 
fully made, without any pressure, a slit along the upper 
surface of other nectaries from the same plants, and 
looked into them, their inner surfaces were quite dry. 

I then examined the nectaries of Gymnadenia cono^psea 
(a plant ranked by some botanists as a true Orchis) 
and of Habenaria hifolia, which are always full of nectai 
up to one-third or two-thirds of their length. The 
inner membrane presented the same structure and was 
covered with papillae as in the foregoing species ; but 
there was a plain difference in the inner and outer 
membranes being closely united, instead of being in 
some degree separated from each other and charged 
with fluid. I was therefore led to conclude that insects 
penetrate the lax inner membrane of the nectaries of 
the above-named Orchids, and suck the copious fluid 
between the two membranes. This was a bold hypo- 
thesis ; for at the time no case was known of insects 
penetrating with their delicate proboscides even the 
laxest membrane. But I have now heard from Mr. 
Trimen, that at the Cape of Good Hope moths and 
butterflies do much injury to peaches and plums by 
puncturing their unbroken skins. In Queensland 
Australia, a moth, the Oj)Mderes fuUonica, bores 
through the thick rind of the orange with its wonder- 
ful proboscis, provided with formidable teeth.* There 
is therefore not the least difficulty in believing that 
Lepidoptera with their delicate proboscides, and bees 

* My son Francis has described ♦ Q. Journal of IMicroscopical 
and figured thitj organ iu the Science,' vol. xv. 1875, p. 385. 



CuAP. 1. SECRETION OF NECTAR. 41 

with their much stronger ones, could penetrate with ease 
the soft inner membrane of the nectaries of the above- 
named Orchids. Dr. H. Muller is also convinced* that 
insects puncture the thickened bases of the standard 
petals of the Laburnum,! and perhaps the petals of 
some other flowers, so as to obtain the included fluid. 

The various kinds of bees which I saw vi^iiting the 
flowers of Orchis morio remained for some time with 
their proboscides inserted into the dry neci;aries, and 
I distinctly saw this organ in constant movement. I 
observed the same fact with Empis in the case of 0. 
maculata ; and on afterwards opening several of the 
nectaries, I occasionally detected minute brown specks, 
due as I believe to the punctures made some time 
before by these flies. Dr. H. Miiller, who kis often 
watched bees at work on several species of Oichis, the 
nectaries of which do not contain any free nectar, fully 
accepts my view. J On the other hand, Delpino still 
maintains that Sprengel is right, and that insects are 
continually deceived by the presence of a nectary, 
though this contains no nectar. § His belief is founded 
chiefly on a statement by Sprengel that insects soon 
find out that it is of no use to visit the nectaries of 
these orchids, as shown by their fertilising only the 



* * Die Befrnchtung,' &c. p. 235. tinct case, Damely, the presence 
t Treviranus conliims (' Bot. of nectar in several monocotyle- 
Zeitung,' 1863, p. 10) a statement donous plants (as described by- 
made by Salisbury, tbat when the Ad. Brongniart in ' Bull. Soc. Bot. 
filaments in the flowers of anotl.er de France,' torn. i. 1854, p. 75) 
leiiuminous plant, Edwardsia, fall between the two walls '^feuillets) 
off, or when they aie cautiously which form the divisions of the 
separated, a large quantity of ovarium. But the nectar in this 
sxceet fluid flows from tlie points case is conducted to the outside 
of separation ; and as befureliaud by a channel ; and the secreting 
there was no tiace of any such surface is homologically an ex- 
fluid, it must have been contained, terior surface, 
as Treviranus remarks, within the J 'Die Befruchtung,' &c. p. 84. 
cellular tissue. I may add an ap- § 'Ult. Osservazioni sulla Di- 
parently similar, but really die- cogamia,' 1875, p. 121. 



42 OPHRL^. Chap. I 

lower and first opened flowers. But this statement is 
completely contradicted by my observations previously 
given, from which it follows that very many of the 
upper flowers are fertilised ; for instance, on a spike 
of 0. loyramidalis with between fifty and sixty flowers, 
no less than forty-eight had their pollinia removed. 
Nevertheless, as soon as I learnt that Delpino still be- 
lieved in Sprengel's view, I selected during the un- 
favourable season of 1875 six old spikes of 0. maculata, 
and divided each into halves, so as to observe whether 
many more capsules were produced by the lower than 
by the upper half. This certainly was not always the 
case ; for in some of the spikes no difference could be 
detected between them ; in others there were more cap- 
sules in the lower, while in others there were more in 
the upper half. A spike of 0. ])yramidalis examined 
in the same manner produced twice as many capsules 
in the upper as in the lower half. Bearing in mind 
these facts and others before given, it appears to me 
incredible that the same insect should go on visiting 
flower after flower of these Orchids, although it never 
obtains any nectar. Insects, or at least bees, are by 
no means destitute of intelligence. They recognise 
from a distance the flowers of the same species, and 
keep to them as long as they can. When humble- 
bees have bitten holes through the corolla, as they 
often do, so as to reach the nectar more easily, hive- 
bees immediately perceive what has been done and 
take advantage of the perforations. When flowers 
having more than a single nectary are visited by many 
bees, so that the nectar is exhausted in most of them, 
the bees which afterwards visit such flowers insert 
their proboscides only into one of the nectaries, and 
if they find this exhausted, they instantly pass on to 
another flower. Can it be believed that bees which 



Chap. I. SECRETION OF NECTAR. 43 

show this much intelligence, should persevere in 
visiting flower after flower of the above-named Orchids, 
and in keeping their proboscides in constant movement 
for some time within the nectaries, in the hope of 
obtaining nectar which is never present? This, as I 
have said, seems to me utterly incredible. 

It has been shown how numerous and beautiful are 
the contrivances for the fertilisation of Orchids. We 
know that it is of the highest importance that the 
poUinia, when attached to the head or proboscis of an 
insect, should be fixed symmetrically, so as not to fall 
either sideways or backwards. We know that in the 
species as yet described the viscid matter of the disc 
sets hard in a few minutes when exposed to the air, 
so that it would be a great advantage to the plant if 
insects were delayed in sucking the nectar, time being 
thus allowed for the disc to become immovably affixed. 
It is manifest that insects must be delayed by having 
to bore through several points of the inner membrane 
of the nectary, and to suck the nectar from the inter- 
cellular spaces ; and we can thus understand why the 
nectaries of the above-named species of Orchis do not 
contain free nectar, but secrete it internally between 
the two membranes. 

The following singular relation supports this view 
in a striking manner. I have found free nectar within 
the nectaries of only five British species of Ophreae, 
namely, in Gymnadenia conoi:)sea and alhida, in 
Hahenaria hifolia and clihrantlia, and in Feristijlus (or 
Habenaria) viridis. The first four of these species have 
the viscid surfaces of the discs of their pollinia naked 
or not enclosed within pouches, and the viscid matter 
does not rapidly set hard when exposed to the air, as if 
it did, it would immediately have been rendered use- 
less; and this shows that it must differ in chemical 



44 OPHKE^. Chap. I 

nature from that in the foregoing species of Orchis. 
But to make sure of this fact I removed the pollinia 
from their anther-cells, so that the upper as well as the 
under surfaces of the viscid discs were freely exposed 
to the air ; in Gymnadenia conojysea the disc remained 
sticky for two hours, and in Habenaria chlorantlia for 
more than twenty-four hours. In Peristylus viridis the 
viscid disc is covered by a pouch-formed membrane, 
but this is so minute that botanists have overlooked 
it. I did not, when examining this species, see the 
importance of ascertaining exactly how soon the 
viscid matter set hard ; but I copy from my notes 
the words written at the time : " disc remains sticky 
for some time when removed from its little pouch." 

Now the meaning of these facts is clear : as the 
viscid matter of the discs of these five latter species is 
so adhesive that it serves to attach the pollinia firmly 
to the insects which visit the flowers, without setting 
hard, there would be no use in the insects being 
delayed by having to bore holes at several points 
through the inner membrane of the nectaries ; and in 
these five species, and in these alone, we find copious 
nectar ready stored for rapid suction in open nectaries. 
On the other hand, whenever the viscid matter sets 
hard by exposure for a short time to the air, it would 
manifestly be advantageous to the plant, if insects 
were delayed in obtaining the nectar ; and in all such 
species the nectar is lodged within intercellular spaces, 
so that it can be obtained only by the inner mem- 
brane being penetrated at several points, and this will 
require time. If this double relation is accidental, 
it is a fortunate accident for the plants ; but I cannot 
believe it to be so, and it appears to me one of the 
most wonderful cases of adaptation which has ever 
been recorded. 



Chap. IL OPHEYS MUSCIFEKA. 45 



CHAPTEK II. 

OPHKE^ — continued. 

Fly and Spider Ophrys — Bee Ophrys, apparently adapted for perpetual 
eelf-fertilisatioQ, but with paradoxical contrivances for intercrossing 
— Herminium monorehis, attachment of the pollinia to the front legs 
of insects — Peristylus viridis, fertilisation indirectly effected by nectar 
secreted from three parts of the labellum— Gymnadenia conopsea. 
and other species — Habenaria or Platanthera chlorantha and 
bifolia, their pulliuia attached to the eyes of Lepidoptera — Other 
species of Habenada — Bonatea — Disa — Summary on the powers of 
movement in the pollinia. 

The genus Ophrys differs from Orchis chiefly in 
having separate pouch-formed rostella,* instead of 
the two being confluent. 

In Ophrys muscifera, or the Fly Ophrys, the chief 
peculiarity is that the caudicle of the pollinium 
(B, fig. 5) is doubly bent. The nearly circular piece 
of membrane, to the under side of which the ball of 
viscid matter adheres, is of considerable size, and forms 
the summit of the rostellum. It is thus freely exposed 



* It is not correct to speak of fold of membrane (see B in fig. 1) 

two robtella, but the inaccuracy projecting between the bases of 

m:'.y be forgiven from its conve- the anther-cells. This folded 

nience. The rostellum strictly is crest (sometimes converted into a 

a single organ, formed by the solid ridge) corresponds with the 

modification of the dorsal stigma smooth surface lying between the 

aTid pistil ; so that in ( iphrys the two pouches in Opiirys, and owes 

two pouches, the two viscid discs, its protuberant and fohlcd condi- 

and the space between them to- tion in Orchis to the two pouches 

getlier form the true rosttllum. having been brouglit toirethtr and 

Again, iu Orchis I l.ave spoken of rendered confluent. Tliis modi- 

the pouch-formed organ as tlie tication will be more fully ex* 

rostellum, but strictly the rostel- plaineil in a future chapter, 
tun includes the little crest or 



16 



OPHRE^. 



CuAP. IL 



to the air, instead of lying almost hidden at the base of 
the anther, as in Orchis, and thus kept damp. Never- 
theless, when a pollinium is removed, the caudicle 
bends downwards in the course of about six minutes, 
Hud, therefore, at an unusually slow rate ; the upper 

Fig. 5. 




OrHRYS MUSCIFERA, OR FlY OpHRYS. 



a. anthei. s. stigma. 

r,r. rostelU. I. labellurn. 

A. Flower viewed in front : the two 
upper petals are almost cylin- 
drical and hairy : the two ros- 
tella stand a little in advance 



of the bases of the anther-cells ; 
but this is not shown from the 
foreshortening of the drawing. 
One of the two pollinia removed 
from its anther-cell, and viewed 
laterally. 



er d still remaining curved. I formerly thought that 
it was incapable of any movement, but have been con- 
vinced by Mr. T. H. Farrer of my error. The ball of 
viscid matter is bathed in fluid within the pouch formed 
by the lower half of the rostellum, and this is necessary, 



Chap. II. OPHRYS MUSCIFEEA. 47 

as the viscid matter quickly sets hard when exposed to 
the air. The pouch is not elastic, and does not spring 
up when the poUinium is removed. Such elasticity- 
would have been useless, as there is here a separate 
pouch for each viscid disc ; whereas in Orchis, after 
one pollinium has been removed, the other has to 
be kept covered up and ready for action. Hence it 
.'ippears that nature had been so economical as to save 
even superfluous elasticity. 

The pollinia cannot, as I have often proved, be shaken 
out of the anther-cells. That insects of some kind 
visit the flowers, though not frequently, and remove 
the pollinia, is certain, as we shall immediately see. 
Twice I have found abundant pollen on the stigmas of 
flowers, in which both pollinia were still in their cells ; 
and no doubt this might have been much oftener ob- 
served. The elongated labellum affords a good landing- 
place for insects : at its base, just beneath the stigma, 
there is a rather deep depression, representing the 
nectary in Orchis ; but I could never see a trace of 
nectar within it ; nor have I ever observed any insects 
approach these inconspicuous and scentless flowers, often 
as I have watched them. There is, however, on each side 
of the base of the labellum a small shining projection, 
having an almost metallic lustre, which appears curi- 
ously like a drop of fluid or nectar ; and as these flowers 
are only visited occasionally by insects, Sprengel's view 
of the existence of sham-nectaries is far more probable 
in this case than in any other known to me. On 
several occasions I have detected minute punctures in 
these protuberances, but I was not able to decide whether 
they had been made by insects, or whether superficial 
cells had spontaneously burst. Similar shining pro- 
tuberances are present on the labella of all the other 
species of Ophrys. The two rostella stand not far 



18 



OPHRE^. 



Chap. II. 



apart, and project over the stigma ; and if any object 
is gently pushed against one of them, the pouch is 
depressed and the viscid ball together with the pol- 
linium adheres to it and is easily removed. 

The structure of the flower leads me to believe that 
small insects (as we shall see in the case of Listera) 
crawl up the labellum to its base, and that in bending 
their heads downwards, so as to puncture and suck, or 
only to examine one of the small shining protuberances, 
they push against the pouch, and a pollinium is attached 
to their heads ; they then fly to another flower, and 
there bending down in a similar manner, the attached 
and doubly-bent pollinium, after the movement of 
depression, strikes the sticky stigmatic surface, and 
leaves pollen on it. Under the next species we shall 
see reason for believing that the natural double cur- 
vature of the caudicle compensates for its slight power 
of movement, compared with that in all the species of 
Orchis. 



In 1858, 17 plants, bearing 57 flowers, j 
growing near each other were examined/ 

In 1858, 25 plants growing in another! 
spot, and bearing 65 flowers . . j 

In 1860, 17 plants, bearing 61 flowers 

In 1861, 4 plants from S. Kent, bearing 241 
flowers (all the previous plants having) 
grown in N. Kent) . . . . j 

Total 


Number of Flowers. 


Both Pollinia 

or one removed 

by Insects. 


Both Poll'nia 
In their Cells. 


30 

15 

28 

15 


27 

50 
33 

9 


88 1 119 

1 



That insects visit the flowers of the Fly Ophrys 
and remove the pollinia, though not efl'ectually or suifi- 



Chap. II. OPHRYS MUSCIFERA. 49 

ciently, the following cases show. During several 
years before 1858 I occasionally examined some flowers, 
and found that only thirteen out of 102 had one or 
both pollinia removed. Although at the time I re- 
corded in my notes that most of the flowers were 
partly withered, I now think that I must have included 
many young flowers, which might perhaps have been 
subsequently visited ; so I prefer trusting to the fol- 
lowing observations. 

We here see that, out of 207 flowers examined, not 
half had been visited by insects. Of the eighty-eight 
flowers visited, thirty-one had only one pollinium re- 
moved. As the visits of insects are indispensable for 
the fertilisation of this Orchid, it is surprising (as in 
the case of Orchis fusca) that the flowers have not been 
rendered more attractive to insects. The number oi 
seed-capsules produced is proportionably even less than 
the number of flowers visited by insects. The year 
1861 was extraordinarily favourable to this species in 
this part of Kent, and I never saw such numbers 
in flower ; accordingly I marked eleven plants, which 
bore forty-nine flowers, but these produced only seven 
capsules. Two of the plants each bore two capsules, 
and three other plants each bore one, so that no less 
than six plants did not produce a single capsule ! 
What are we to conclude from these facts ? Are the 
conditions of life unfavourable to this species, though 
during the year just alluded to it was so numerous in 
some places as to deserve to be called quite common ? 
Could the plant nourish more seed ; and would it be of 
any advantage to it to produce more seed ? Why does 
it produce so many flowers, if it already produces a 
sufiiciency of seeds ? Something seems to be out of 
order in its mechanism or in its conditions. We shall 
presently see that Ophrys apifera or the Bee Ophrys 




50 OPHTvE^. Chap. II. 

presents a wonderful contrast in every flower producing 
a capsule. 

O^phys aranifera, or the Spider Ophrys. — I am in- 
debted to Mr. Oxenden for some spikes of this rare 
Fig. 6. species. Whilst the poUinia 

remain enclosed within their 
cells, the lower part of the cau- 
dicle projects up in a straight 
line from the viscid disc, and 
therefore has a very different 
'b' ^ form from the corresponding 

Ophiys aranifera. part of the Caudiclc of 0. mUS- 

A. Poiiinium before the act of cifeva ; but the Upper part (A, 

B. PoiiinkmiTfter'the act of fig- 6) is a little bent forward, 

depression. that is, towards the labellum. 

The point of attachment of the caudicle to the disc 
is hidden within the bases of the anther-cells, and 
is thus kept damp ; consequently, as soon as the 
pollinia are exposed to the air, the usual movement of 
depression takes place, and they sweep through an 
angle of about ninety degrees. By this movement 
they assume, supposing them to be attached to an 
insect's head, a position exactly adapted for striking 
the stigmatic surface, which is situated, relatively to 
the potich-formed rostella, rather lower down in the 
flower than in the Fly Ophrys. 

I examined fourteen flowers of the Spider Ophrys, 
several of which were partly withered; and in none 
were both pollinia, and in three alone was one poiiinium 
removed. Hence this species, like the Fly Ophrys, 
is but little visited by insects in England. In parts 
of Italy it is even less visited, for Delpino states* 
that in Liguria hardly one flower out of 3000 sets a 



* ' Ult. OBsert. P. Dico;;amia,' &c. Parte i. 1868-69, p. 1 77. 



Chap. II. OPIIRYS ARACHNITES. 51 

capsule, though near Florence rather more capsules 
are produced. The labellum does not secrete any 
nectar. The flowers, however, must be occasionally 
visited and fertilised by insects, for Delpino found* 
pollen-masses on the stigmas of some flowers which 
still retained both their own pollinia. 

The anther-cells are remarkably open, so that with 
some plants which were sent me in a box, two pair 
of pollinia fell out, and stuck by their viscid discs 
to the petals. Here w^e have an instance of the first 
appearance of a trifling structure which is of not the 
least use to its possessor, but becomes when a little 
more developed, highly beneficial to a closely-allied 
species ; for although the open state of the anther-cells 
is useless to the Spider Ophrys, it is of the highest 
importance, as we shall presently see, to the Bee 
Ophrys. The flexure of the upper end of the caudicle 
of the pollinium is of service to the Spider and Fly 
Ophrys, by aiding the pollen-masses, when carried by 
insects to another flower, to strike the stigma ; but by 
an increase of this bend together with increased flexi- 
bility in the Bee Ophrys, the pollinia become adapted 
for the widely different purpose of self-fertilisation. 

Oijilirys arachnites. — This form, of which Mr. Oxenden 
sent me several living specimens, is ^w. 7. 
considered by some botanists as only a 
variety of the Bee Ophrys, by others as a 
distinct species. The anther-cells do not 
stand so high above the stigma, and do 
not overhang it so much, as in the Bee 
Ophrys, and the pollen masses are more PoiUnium of 
elongated. The caudicle is only two- Ophrys arachnite 
thirds, or even only half as long as that of the Bee 




' Feroiidazi'iic nelle Piante Antooarp 'O,' 1807. p. -0. 



52 OPHKE^. Chap. IL 

Ophiys, and is miicli more rigid ; the upper part is 
naturally curved forward; the lower part undergoes 
the usual movement of depression, when the pollinia 
are removed from their cells. The pollen-masses 
never fall spontaneously out of their cells. This plant, 
therefore, differs in every important respect from 0. 
aioifera, and seems to be much more closely allied to 
0. aranifera. 

Ophrijs scolopax of Cavanilles. — This form inhabits 
the north of Italy and the south of France. JMr. 
Moggridge says* that at Mentone it never shows any 
tendency to fertilise itself, whilst at Cannes the pollen- 
masses naturally fall out of their cells and strike the 
stigma. He adds : " This material difference between 
the two is accomplished by a very slight bend in the 
anther-cells, which are prolonged into a beak of variable 
length, in the case of the self-fertilising blossoms." 

Ophrijs apifera, — The Bee Ophrys differs widely 
from the great majority of Orchids in being excellently 
constructed for fertilising itself. The two pouch -formed 
rostella, the viscid discs, and the position of the stigma, 
are nearly the same as in tLe other species of Ophrys ; 
but the distance of the two pouches from each other, 
and the shape of the pollen-masses are somewhat 
variable.! The caudicles of the pollinia are remark- 
ably long, thin, and flexible, instead of being, as 
in all the other Ophrese seen by me, rigid enough 
to stand upright. They are necessarily curved 
forward at their upper ends, owing to the shape of 
the anther-cells ; and the pear-shaped pollen-masses 
lie embedded high above and directly over the 

* 'Journ. Liiin. Soc' vol. viii. symmetrically confluent as iu tho 

1865, p. 258. genus Orchis, and with the two 

t I once found a single flower viscid discs likewise confluent, as 

on the summit of a spike, with in Orchis pyramidalis or Jdrcina. 
the two rostella as completely and 



Chap. II. 



OPHRYS APIFERA. 



53 



stigma. The anther-cells naturally open soon after 
the flower is fully expanded, and the thick ends of 
the pollen-masses then fall out, the viscid discs still 
remaining in their pouches. Slight as is the weight 
of the pollen-masses, yet the caudicles are so thin and 
quickly become so flexible, that in the course of a few 
hours they sink down, until they hang freely in the air 

Fig. 8. 




OpHRTS APIFERA, OR BeE OpHRYS. 



a. anther. 

i.l. label lum. 

A. Side view of flower, with the 
upper sepal and the two upper 
petals removed. One polliuium, 
with its disc still in its pouch, 
is represented as jast falling 



out of the anther-cell; and 
the other has fiillen almost to 
its full extent, opposite to the 
hidden stigmatic surface. 
B. Pollinium in the position in 
which it lies embedded. 



(see lower pollen-mass in fig. A) exactly opposite to 
and in front of the stigmatic surface. In this position 
a breath of air, acting on the expanded petals, sets 
the flexible and elastic caudicles vibrating, and they 
almost immediately strike the viscid stigma, and, 
being there secured, impregnation is effected. To 
make sure that no other aid was requisite, though 



54 OPHRE^. Chap. IL 

the experiment was superfluous, I covered up a plant 
under a net, so that the wind, but no insects, could 
pass in, and in a few days the pollinia became attached 
to the stigmas. But the pollinia of a spike kept in 
water in a still room remained free, suspended in front 
of the stigma, until the flowers withered. 

Robert Brown first observed that the structure of the 
Bee Ophrys is adapted for self-fertilisation.* When 
we consider the unusual and perfectly-adapted length, 
as well as the remarkable flexibility of the caudicles ; 
when we see that the anther-cells naturally open, and 
that the masses of pollen, from their weight, slowly 
fall down to the exact level of the stigmatic surface, 
and are there made to vibrate by the slightest breath 
of wind until the stigma is struck ; it is impossible 
to doubt that these several points of structure and 
function, which occur in no other British Orchid, are 
specially adapted for self- fertilisation. 

The result is what might have been anticipated. 1 
have often noticed that the spikes of the Bee Ophrys 
apparently produced as many seed-capsules as flowers ; 
and near Torquay I carefully examined many dozen 
plants, some time after the flowering season ; and on 
all I found from one to four, and occasionally five, 
fine capsules, that is, as many capsules as there had 
been flowers. In extremely few cases, with the excep- 
tion of a few deformities, generally on the summit of 
the spike, could a flower be found which had not pro- 
duced a capsule. Let it be observed what a contrast 
this species presents with the Fly Ophrys, which 
requires insect aid for its fertilisation, and which from 
forty-nine flowers produced only seven capsules ! 

* ' Transact. Linn. Soc' vol. common to the genus. As far aa 
xvi. p. 740. Brown erroneously the fouf British species are con- 
believed that this peculiarity was cerned, it applies to this one alone. 



Chap. II. OPHKYS APIFERA. 55 

From what I had then seen of otlier Orchids, I 
was so much surprised at the self-fertilisation of this 
species, that I examined during many years, and asked 
others to examine, the state of the pollen-masses in 
many hundreds of flowers, collected in various parts of 
England. The particulars are not worth detailing; 
but I may give as an instance, that Mr. Farrer 
found in Surrey that not one flower out of 106 
had lost both pollinia, and that only three had lost 
a single one. In the Isle of Wight, Mr. More 
examined 136 flowers, and of these the very unusual 
number of ten had lost both, and fourteen had lost 
one; but then he found that in eleven cases the 
caudicles had been gnawed through apparently by 
snails, the discs still remaining in their pouches ; so 
that the pollinia had not been carried away by insects. 
In some few cases, also, in which I found the pollinia 
removed, the petals were marked with the slime of 
snails. Nor must we forget that a blow from a 
passing animal, and possibly heavy storms of wind 
might occasionally cause the loss of one or both 
pollinia. 

During most years the pollen-masses of the many 
hundred flowers which were examined, adhered with 
the rarest exceptions to the stigma, with their discs still 
enclosed within the pouches. But in the year 1868, 
from some cause the nature of which I cannot conjecture, 
out of 116 flowers gathered in two localities in Kent, 
seventy -five retained both pollinia in their cells ; ten 
had one pollinium, and only thirty-one had both 
adhering to the stigma. Long and often as I have 
watched plants of the Bee Ophrys, I have never seen 
one visited by any insect.* Eobert Brown imagined 



• Mr. Gerard E. Smith, in his 'Catalogue of Plants of S. Kent, 



66 OPHRE^. Chap. II. 

that the flowers resembled bees in order to deter their 
visits, but this seems extremely improbable. The 
flowers with their pink sepals do not resemble an}'- 
British bee, and it is probably true, as I have heard it 
said, that the plant received its name merely from the 
hairy labellum being somewhat like the abdomen of a 
humble-bee. We see how fanciful many of the names 
are, — one species being called the Lizard and another 
the Frog Orchis. The resemblance of 0, muscifera to 
a fly is very much closer than that of 0. apifera to a 
bee ; and yet the fertilisation of the former absolutely 
depends on and is effected by the means of insects. 

All the foregoing observations relate to England, 
but Mr. Moggridge made similar ones on the Bee 
Ophrys in Northern Italy and Southern France, as did 
Treviranus* in Germany, and Dr. Hooker in Morocco. 
We may therefore conclude, — from the pollinia spon- 
taneously falling on the stigma — from the co-related 
structure of all the parts for this purpose — and from 
almost all the flowers producing seed-capsules — that 
this plant has been specially adapted for self-fertilisa- 
tion. But there is another side to the case. 

When an object is pushed against one of the 
pouches of the rostellum, the lip is depressed, and the 
large viscid disc adheres firmly to it ; and when the 
object is removed, so is the pollinium, but perhaps 
not quite so readily as in the other species of 
Ophrys. Even after the pollen-masses have naturally 
fallen out of their cells on to the stigma, their removal 
can sometimes be thus effected. As soon as the disc is 



1S29, p. 25, says: "Mr. Piice cannot conjecture, 

has frequently witnessed attacks * ' Dot. Zeitung,' 1863, p. 241. 

made upon the Bee Orchis by a This botanist at first doubted my 

bee, simiLir to those of the observations on Ophrys apifera 

troublesome Apis muscorum." and aranifera, but has since fully 

What this sentence means I confirmed them. 



CuAP. IL OPHRYS APIFERA. 57 

drawn out of its pouch a movement of depression 
commences, by which the pollinium if attached to 
the front of an insect's head would be brought into 
a proper position for striking the stigma. When a 
pollen-mass is placed on the stigma and then with- 
drawn, the elastic threads by which the packets are 
tied together break, and leave several packets on the 
viscid surface. In all other Orchids the meaning of 
these several contrivances is unmistakably clear — 
namely, the downward movement of the lip of the ros- 
tellum when gently pushed — the viscidity of the disc 
— the depression of the caudicle as soon as the disc 
is exposed to the air — the rupturing of the elastic 
threads — and the conspicuousness of the flower. Are 
w^e to believe that these adaptations for cross-fertilisa- 
tion in the Bee Ophrys are absolutely purposeless, as 
would certainly be the case if this species has always 
been and will always be self-fertilised ? It is, however, 
just possible that insects, although they have never 
been seen to visit the flowers, may at rare intervals 
transport the poUinia from plant to plant, during such 
seasons as that of 1868, when the pollinia did not all 
fall out of the anther- cells so as to reach the stigmas. 
The whole case is perplexing in an unparalleled degree, 
for we have in the same flower elaborate contrivances 
for directly opposed objects. 

That cross-fertilisation is beneficial to most Orchids, 
we may infer from the innumerable structures serving 
for this purpose which they present ; and I have 
elsewhere shown in the case of many other groups of 
plants * that the benefits thus derived are of high 
importance. On the other hand, self-fertilisation is 
manifestly advantageous in as far as it ensures a full 

* ' The Effects of Cross and Self- Fertilisation in the Vegetable 
Kingdom,' 1876. 

4 



58 OPHRE^. Chap. II. 

supply of seed; and we have seen with the other 
British species of Opnrys which cannot fertilise them- 
selves, how small a proportion of their flowers produce 
capsules. Judging therefore from the structure of 
the flowers of 0. apifera, it seems almost certain that 
at some former period they were adapted for cross- 
fertilisation, but that failing to produce a sufficiency 
of seed they became slightly modified so as to fertilise 
themselves. It is, however, remarkable on this view, 
that none of the parts in question show any tendency 
to abortion — that in the several and distant countries 
which the plant inhabits, the flowers are still con- 
spicuous, the discs still viscid, and the caudicles still 
retain the power of movement when the discs are ex- 
posed to the air. The metallic points at the base of 
the labellum are however smaller than in the other 
species ; and if these serve to attract insects, this dif- 
ference is of some signification. As it can hardly be 
doubted that 0. apifera was at first constructed so as 
to be regularly cross-fertilised, it may be asked will it 
ever revert to its former state ; and if it does not so 
revert, will it become extinct ? These questions cannot 
be answered, any more than in the case of those plants 
which are now propagated exclusively by buds, stolons, 
&c., but which produce flowers that rarely or never set 
any seed ; and there is reason to believe that a sexual 
propagation is closely analogous to long-continued 
self-fertilisation. 

Finally Mr. Moggridge has shown that in North 
Italy Oplirys apifera, aranifera, arachnites, and scolopax 
are connected by so many and such close intermediate 
links,* that all seem to form a single species in 

♦ These forms are illustrated by * Verhandlungen der Kaiserl. 

beautiful coloured drawings in Leop. Car. Akad.' (Nov. Act.), 

tlie ' Flora of Mentone,' pi. 43 to torn. xxxv. 1869 
45: and in his memoir in the 



Chap. II. HERMINIUM MONOKCHIS. 59 

accordance with the belief of Linnaeus, who grouped 
them all together under the name of Ophrys insectifera, 
Mr. Moggridge further shows that in Italy 0. aranifera 
flowers first, and 0. apifera last, the intermediate 
forms at intermediate periods ; and according to Mr. 
Oxenden, the same fact holds good to a certain extent 
in Kent. The three forms which inhabit England do 
not seem to blend into one another as in Italy, and I 
am assured by Mr. Oxenden, who has closely attended 
to these plants in their native homes, that 0. aranifera 
and ajpifera always grow in distinct spots. The case 
therefore is an interesting one, as here we have forms 
which may be and generally have been ranked as true 
species, but which in North Italy have not as yet been 
fully differentiated. The case is all the more interest- 
ing, as the intermediate forms can hardly be due to 
the crossing of 0. aranifera with ajnfera ; this latter 
species being regularly self-fertilised and apparently 
never visited by insects. Whether we rank the several 
forms of Ophrys as closely allied species or as mere 
varieties of the same species, it is remarkable that 
they should differ in a character of such physiological 
importances as the flowers of some being plainly 
adapted for self-fertilisation, whilst the flowers of 
others are strictly adapted for cross-fertilisation, being 
utterly sterile if not visited by insects. 

Herminium monorchis. — The Musk Orchis, which is 
a rare British plant, is generally spoken of as having 
naked glands or discs, but this is not strictly correct. 
The disc is of unusual size, nearly equalling the mass 
of pollen-grains : it is subtriangular, with one side pro- 
tuberant, and somewhat resembles a distorted helmet 
in shape : it is formed of hard tissue with the base 
hollowed out, and viscid ; the base resting on and 
being covered by a narrow strip of membrane, which is 



60 OPHREJS. CuAP. II 

easily pushed away, and answers to the pouch in 
Orchis. The whole upper part of the helmet answers 
to the minute oval bit of membrane to which the 
caudicle of Orchis is attached and which in Ophrys 
is larger and convex. When the lower part of the 
helmet is moved by any pointed object, the point 
readily slips into its hollow base, and is there held so 
firmly by the viscid matter, that the whole helmet 
appears adapted to stick to some prominent part of an 
insect's body. The caudicle is short and very elastic ; 
it is attached not to the apex of the helmet, but to the 
hinder end ; if it had been attached to the apex, the 
point of attachment would have been freely exposed to 
the air and not kept damp ; and then the pollinium 
when removed from its cell would not have been 
quickly depressed. 

This movement is well marked, and serves to bring- 
the end of the pollen-mass into a proper position for 
striking the stigma. The two viscid discs stand wide 
apart. There are two transverse stigmatic surfaces, 
meeting by their points in the middle ; but the broad 
part of each lies directly beneath each disc. The 
labellum is remarkable from not differing much in 
shape from the two upper petals, and from not always 
occupying the same position in reference to the axis 
of the plant, owing to the ovarium being more or less 
twisted. This state of the labellum is intelligible, for 
as we shall see, it does not serve as a landing-place for 
insects. It is upturned, and together with the two 
other petals makes the whole flower in some degree 
tubular. At its base there is a hollow so deep as 
almost to deserve to be called a nectary ; but I could 
not perceive any nectar, which, as I believe, remains 
enclosed in the intercellular spaces. The flowers are 
very small and inconspicuous, but emit a strong honey- 



Chap. II. HERMINIUM MONORCHIS. 61 

like odour. They seem highly attractive to insects ; in 
a spike with only seven flowers recently open, four had 
both poUinia, and one had a single pollinium removed. 
When the first edition of this book appeared I did 
not know how the flowers were fertilised, but my son 
George has made out the whole process, which is 
extremely curious and differs from that in any other 
Orchid known to me. He saw various minute insects 
entering the flowers, and brought home no less than 
twenty-seven specimens with pollinia (generally with 
only one, but sometimes with two) attached to them. 
These insects consisted of minute Hymenoptera (of 
which Tetrasticlius diaphantus was the commonest), 
of Diptera and Coleoptera, the latter being MaltJiodes 
hrevicollis. The one indispensable point appears to 
be that the insect should be of very small size, the 
largest being only the -^ of an inch in length. The 
pollinia were always attached to the same place, 
namely, to the outer surface of the femur of one of the 
front legs, and generally to the projection formed by 
the articulation of the femur with the coxa. The 
cause of this peculiar mode of attacliment is suffici- 
ently clear : the middle part of the labellum stands so 
close to the anther and stigma, that insects always enter 
the flower at one corner, between the edge of the 
labellum and one of the upper petals ; they also almost 
always crawl in with their backs turned directly or 
obliquely towards the labellum. My son saw several 
which began to crawl into the flowers in a different 
position ; but they came out and changed their posi- 
tion. Standing in either corner of the flower, with 
their backs turned towards the labellum, they insert 
their heads and fore legs into the short nectary, which 
is seated between the two widely separated viscid discs. 
I ascertained that they had occupied this position by 



62 OPHRE^. Chap. II. 

finding three dead insects, permanently glued to the 
•Uses. Whilst sucking the nectar, which takes two or 
three minutes, the projecting joint of the femur stands 
under the large helmet-like viscid disc on either side ; 
and when the insect retreats, the disc exactly fits on 
and is glued to the prominent joint, or to the surface 
of the femur. The movement of depression in the 
caudicle now takes place, and the mass of pollen-grains 
then projects just beyond the tibia ; so that the insect, 
when entering another flower, can hardly fail to ferti- 
lise the stigma, which is situated directly beneath the 
disc on either side. 

Fig. 9. 



Peristylus viridis, or Frog Orchis, 
Front view of flower. 



a. anther. 
s. stigma. 
n. orifice of central nectary. 



n'u. lateral nectaries. 
/. labellum. 



Peristylus viridis. — This plant, which bears the odd 
name of the Frog Orchis, has been placed by many 
botanists in the genus Habenaria or Platanthera; but 
as the discs are not naked, it is doubtful whether this 



Chap. II. PEKISTYLUS VIRIDIS. 63 

classification can be correct. The rostella are small 
and widely separated from each other. The viscid 
matter on the under side of the disc forms an oval ball 
which is enclosed within a small pouch. The upper 
membrane to which the caudicle is attached is of large 
size relatively to the whole disc, and is freely exposed 
to the air. Hence probably it is that the pollinia when 
removed from their cases do not become depressed 
until, as Mr. T. H. Farrer has observed, twenty or 
thirty minutes have elapsed. Owing to this long 
interval, I formerly thought that they did not undergo 
any movement of depression. Supposing a pollinium 
to be attached to the head of an insect, and to have 
become depressed, it will stand at the proper angle, 
vertically, for striking the stigma. But from the 
lateral position of the anther-cells, notwithstanding 
that they converge a little towards their upper ends, 
it is difficult at first to see how the pollinia when 
removed by insects are afterwards placed on the 
stigma ; for this is of small size and is situated in the 
middle of the flower between the two widely separated 
rostella. 

The explanation is, 1 believe, as follows. The base 
of the elongated labellum forms a rather deep hollow 
in front of the stigma, and in this hollow, but some way 
in advance of the stigma, a minute slit-like orifice (n) 
leads into a short bilobed nectary. Hence an insect, 
in order to suck the nectar with which the nectary is 
filled, would have to bend down its head in front of 
the stigma. The labellum has a medial ridge, which 
would probably induce an insect first to alight on 
either side ; but, apparently to make sure of this, 
besides the true nectary, there are two spots (nn) which 
secrete drops of nectar on each side at the base of 
the labellum, bordered by prominent edges, directly 



64 OPHRE.E. CuAP. II 

beneath the two pouches. Now let us suppose an insect 
to alight on one side of the labellum so as first to lick 
up the exposed drop of nectar on this side ; from the 
position of the pouch exactly over the drop, it would 
almost certainly get the pollinium of this side attached 
to its head. If it were now to go to the mouth of the 
true nectary, the pollinium attached to its head from 
not having as yet become depressed would not touch 
the stigma ; so that there would be no self-fertilisation. 
The insect would then probably suck the exposed drop 
of nectar on the other side of the labellum, and would 
perhaps get another pollinium attached to its head ; it 
would thus be considerably delayed by having to visit 
the three nectaries. It would then visit other flowers 
on the same plant, and afterwards flowers on a distinct 
plant ; and by this time, but not before, the pollinia 
will have undergone the movement of depression and 
will be in a proper position for effecting cross-fertilisa- 
tion. It thus appears that the secretion of nectar at 
three separate points of the labellum, — the wide dis- 
tance apart of the two rostella, — and the slow down- 
ward movement of the caudicle without any lateral 
movement — are all correlated for the same purpose of 
cross-fertilisation. 

To what extent this Orchis is frequented by insects, 
and what the kinds are, I do not know, but several of 
the flowers on two spikes, sent me by the Eev. B. S. 
Maiden, had a single pollinium removed, and one 
flower had both removed. 

We now come to two genera, namely, Gymnadenia 
and Habenaria or Platanthera, including four British 
species, which have uncovered viscid discs. The viscid 
matter, as before remarked, is of a somewhat different 
nature from that in Orchis, Ophrys, &c., and does not 



CUAK. II. 



GYMNADENIA CONOPSEA. 



65 



rapidly set hard. Their nectaries are stored with free 
nectar. With respect to the uncovered condition of 
the discs, the last species, or Peristijlus viridis, is in 
an almost intermediate condition. The four following 
species compose a much broken series. In Gymna- 
denia conopsea the vicid discs are narrow and much 
elongated, and lie close together ; in G. albida they 
are less elongated, but still approximate ; in Hdbenaria 
hifolia they are oval and far apart ; and, lastly, in II. 
ehlorantha they are circular and much farther apart. 

Gymnadenia conopsea. — In general appearance this 
plant resembles pretty closely a true Orchis. The 
poUinia differ in having naked, narrow, strap-shaped 

Fig. 10. 



GymXADENIA CONOPSEA. 



A. Pollinium, before the act of 
depression. 



B. Pollinium, after the act of de- 
pression, but before it has 
closely clasped the disc. 



discs, which are as long as the caudicles (fig. 10). 
When the pollinia are exposed to the air the caudicle 
is depressed in from thirty to sixty seconds ; and as 
the posterior surface of the caudicle is slightly hol- 
lowed out, it closely clasps the upper membranous 
surface of the disc. The mechanism of this movement 
will be described in the last chapter. The elastic 
threads by which the packets of pollen are bound to- 
gether are unusually weak, as is likewise the case with 



66 OPHRE^. Chap. IL 

the two following species of Habenaria : this was well 
shown by the state of specimens which had been kept 
in spirits of wine. This weakness apparently stands in 
relation to the viscid matter of the discs not setting 
hard and dry as in Orchis; so that a moth with a 
pollinium attached to its proboscis might be enabled to 
visit several flowers without having the whole polli- 
nium dragged off by the first stigma which was struck. 
The two strap-shaped discs lie close together, and form 
the arched roof of the entrance into the nectary. 
They are not protected, as in Orchis, by a lower lip or 
pouch, so that the structure of the rostellum is simpler. 
When we come to treat of the homologies of the ros- 
tellum we shall see that this difference is due to a 
small change, namely, to the lower and exterior cells 
of the rostellum resolving themselves into viscid 
matter ; whereas in Orchis the exterior surface retains 
its early cellular or membranous condition. 

As the two viscid discs form the roof of the mouth of 
the nectary, and are thus brought down near to the 
labellum, the two stigmas, instead of being confluent 
and standing beneath the rostellum, as in most of 
the species of Orchis, are lateral and separate. These 
stigmas consist of protuberant, almost horn-shaped, 
processes on each side of the nectary. That their 
surfaces are really stigmatic I ascertained by finding 
them deeply penetrated by a multitude of pollen- 
tubes. As in the case of Orchis 'pyramidalis, it is a 
pretty experiment to push a fine bristle straight into 
the narrow mouth of the nectary, and to observe how 
certainly the narrow elongated viscid discs, forming 
the roof, stick to the bristle. When the bristle is 
withdrawn, the pollinia adhering to its upper side 
are withdrawn ; and as the discs form the sides of 
the arched roof, they adhere somewhat to the sides 



Chap. II. GYMNADENIA CONOPSEA. 67 

of the bristle. They then quickly become depressed so 
as to lie in the same line with the bristle, — one a little 
on one side, and the other on the other side ; and if 
the bristle, held in the same relative position, be now 
inserted into the nectary of another flower, the two 
ends of the pollinia accurately strike the two protu- 
berant stigmatic surfaces, situated on each side of the 
mouth of the nectary. 

The flowers smell sweet, and the abundant nectar 
always contained in their nectaries seems highly 
attractive to Lepidoptera, for the pollinia are soon and 
effectually removed. For instance, in a spike with 
forty-five open flowers, forty-one had their pollinia 
removed, or had pollen left on their stigmas: in 
another spike with fifty-four flowers, thirty-seven had 
both pollinia, and fifteen had one pollinium, removed ; 
so that only two flowers in the whole spike had neither 
pollinium removed. 

My son George went at night to a bank where 
this species grows plentifully, and soon caught Plusia 
chrysitis with six pollinia, P. gaytima with three, Anaitis 
plagiata with five, and Triphmna p-onuba with seven 
pollinia attached to their proboscides. I may add 
that he also caught the first-named moth in my 
flower-garden, with the pollinia of this Orchis attached 
to its proboscis, but with all the pollen-grains removed, 
although the garden is a quarter of a mile distant from 
any spot where the plant grows. Many of the above 
moths had only a single pollinium attached, somewhat 
laterally to their proboscides ; and this would happen 
in every case, unless the moth stood directly in front 
of the nectary and inserted it proboscis exactly be- 
tween the two discs. But as the labellum is rather 
broad and flat, with no guiding ridges like those on 
the labellum of Orchis jjyramidalis, there is notliing to 



68 OPHEE^. Chap. II 

compel motlis to insert their proboscides symmetrically 
into the nectary, and there would be no advantage in 
their doing so. 

Gifmnadeiiia alhida. — The structure of the flower of 
this species resembles in most respects that of the 
last ; but, owing to the upturning of the labellum, it 
is rendered almost tubular. The naked elongated 
discs are minute and approximate. The stigmatic sur- 
faces are partially lateral and divergent. The nectary 
is short, and full of nectar. Small as the flowers are, 
they seem highly attractive to insects : of the eighteen 
lower flowers on one spike, ten had both, and seven 
had one pollinium removed ; on some older spikes all 
the pollinia had been removed, except from two or 
three of the uppermost flowers. 

Gymnadenia odoratissima is an inhabitant of the 
Alps, and is said by Dr. H. Miiller* to resemble in 
all the above characters G. conopsea. As the flowers, 
which are pale coloured and highly perfumed, are not 
visited by butterflies, he believes that they are fertilised 
exclusively by moths. The North American G. tri- 
dentata, described by Professor Asa Gray,t differs in an 
important manner from the foregoing species. The 
anther opens in the bud, and the pollen-grains, which 
m the British species are tied together by very weak 
threads, are here much more incoherent, and some in- 
variably fall on the two stigmas and on the naked 
cellular tip of the rostellum ; and this latter part, 
strange to say, is penetrated by the pollen-tubes. The 
flowers are thus self-fertilised. Nevertheless, as Pro- 
fessor Gray adds, " all the arrangements for the removal 



♦ 'Nature,* Dec. 31, 1874, p. note p. 200 ; and vol. xxxvi. 18G3, 

109. p. 293. In the latter paper he 

t ' American Journal of Science,' adds some remarks on G.Jlava and 

vol. xxxiv. 1862, p. 426, and foot- nivea. 



Chap. II. 



HABENARIA CnLORANTHA. 



69 



of the pollinia by insects, including the moYement of 
depression, are as perfect as in the species which 
depend upon insect aid." Hence there can be little 
doubt that this species is occasionally cross-fertilised. 




Habenaria CHLORAirrnA, or Butterfly Orchis. 



a a, anther-cells. 

d. disc of pollinium. 

8. stigma. 

n. nectary. 

n'. orifice of nectary. 

/. labellura. 

A. Flower viewed in front, with all 
the sepals and petals removed 
except the labellum with its 
nectary, which is turned to one 
side. 



B. A pollinium. (This has hardly 

a sufficiently elongated appear- 
ance.) The drum-like pedicel 
is hidden behind the disc. 

C. Diagram, giving a section 

through the viscid disc, the 
drum-like pedicel, and the 
attached end of the caudicle. 
The viscid disc is formed of an 
upper membrane with a layer 
of viscid matter beneath. 



Habenaria or PJafanthera clilorantlia, — The pollinia 
of the Large Butterfly Orchis differ considerably from 
those of any species hitherto mentioned. The two 



70 OPHEE^. Chap. II. 

anther-cells are separated from each other by a wide 
space of connective membrane, and the pollinia are 
enclosed in a backward sloping position (fig. 11). The 
viscid discs front each other, and stand in advance of 
the stigmatic surface. In consequence of their forward 
position, the caudicles and pollen-masses are much 
elongated. Each viscid disc is circular, and, in the 
early bud, consists of a mass of cells, of which the 
exterior layers (answering to the lip or pouch in 
Orchis) resolve themselves into adhesive matter. This 
matter has the property of remaining adhesive for at 
least twenty-four hours after the poUinium has been 
removed from its cell. The disc, externally covered 
with a thick layer of adhesive matter (see fig. C, 
which stands so that the layer of viscid matter is below) 
is produced on its opposite and embedded side into 
a short drum-like pedicel. This pedicel is continuous 
with the membranous portion of the disc and is formed 
of the same tissue. The caudicle of the pollinium is 
attached in a transverse direction to the embedded end 
of the pedicel, and its extremity is prolonged, as a bent 
rudimentary tail, just beyond the drum. The caudicle 
is thus united to the viscid disc in a very different 
manner, and in a plane at right angles, to what occurs 
in the other British Orchids. In the short drum- 
like pedicel, we have a small development of the long 
pedicel of the rostellum, which is so conspicuous in 
many Yandeae, and which connects the viscid disc with 
the true caudicles of the pollinia. 

The drum-like pedicel is of the highest importance, 
not only by rendering the viscid disc more prominent 
and more likely to stick to the face of an insect whilst 
inserting its proboscis into the nectary beneath the 
stigma, but on account of its power of contraction. 
The pollinia lie inclined backwards in their cells (see 



Chap. IL HABENARIA CHLORANTHA. 71 

fig. A), above and some way on each side of the stig- 
matic surface ; if attached in this position to the head 
of an insect, the insect might visit any number of 
flowers, and no pollen would be left on the stigma. 
But observe what takes place : in a few seconds after the 
inner end of the drum-like pedicel has been removed 
from its embedded position and exposed to the air, one 
side of the drum contracts, and this contraction draws 
the thick end of the poUinium inwards, so that the 
caudicle and the viscid surface of the disc are no longer 
parallel, as they were at first, and as they are repre- 
sented in the section, fig. G. At the same time the 
drum rotates through nearly a quarter of a circle, and 
this moves the caudicle downwards, like the hand of 
a clock, depressing the thick end of the pollinium or 
mass of pollen-grains. Let us suppose the right-hand 
disc to be affixed to the right side of an insect's face, 
and by the time required for the insect to visit 
another flower on another plant, the pollen-bearing 
end of the pollinium will have moved downwards 
and inwards, and will now infallibly strike the viscid 
surface of the stigma, situated in the middle of the 
flower beneath and between the two anther-cells. 

The little rudimentary tail of the caudicle projecting 
beyond the drum-like pedicel is an interesting point 
to those who believe in the modification of species ; 
for it shows us that the disc has been carried a little 
inwards, and that primordially the two discs stood even 
still further in advance of the stigma than they do 
at present. We thus learn that the parent-form ap- 
proached in this respect the structure of that extra- 
ordinary Orchid, the Bonatea speciosa of the Cape of 
Good Hope. 

The remarkable length of the nectary, containing 
much free nec;tar, the white coloui of the conspicuous 



72 OPIIKE^. Chap. II 

flowers, and tlie strong sweet odour emitted by them at 
night, all show tnat this plant depends for its fertilisa- 
tion on the larger nocturnal Lepidoptera. I have 
often found spikes with almost all the pollinia removed. 
From the lateral position and distance of the two 
viscid discs from each other, the same moth would 
generally remove only one pollinium at a time ; and 
in a spike which had not as yet been much visited, 
three flowers had both pollinia, and eight flowers had 
only one pollinium removed. From the position of 
the discs it might have been anticipated that they 
would adhere to the side of the head or face of moths ; 
and Mr. F. Bond sent me a specimen of Hadena dentina 
with one eye covered and blinded by a disc, and a 
specimen of Plusia v. aureum with a disc attached to 
the edge of the eye. Mr. Marshall* collected twenty 
specimens of Gucidlia umhratica on an island in Der- 
went water, separated by half-a-mile of water from any 
spot where H. cldorantha grew ; nevertheless, seven of 
these moths had the pollinia of this Orchid afiixed to 
their eyes. Although the discs are so adhesive that 
almost all the pollinia in a bunch of flowers which was 
carried in my hand and thus shaken were removed 
by adhering to the petals or sepals, yet it is certain 
that moths, probably the smaller species, often visit 
these flowers without removing the pollinia; for on 
examining the discs of a large number of pollinia 
whilst still in their cells I found minute Lepido- 
pterous scales glued to them. 

The cause of the flowers of various kinds of Orchids 
being constructed so that the pollinia are always 
afiixed to the eyes or proboscides of Lepidoptera, and 
to the naked foreheads or proboscides of Hymenoptera, 



♦ ' Nature,' Sept. 12, 1872, p. 393. 



Chap. II. IIABENAEIA BIFOLIA. 73 

no doubt is that the viscid discs cannot adhere to 
a scaly or very hairy surface; the scales themselves 
being easily detached. Variations in the structure of 
the flower of an Orchid, unless they led to the viscid 
discs touching some part of the body of an insect 
where they would remain firmly attached, would be of 
no service, but an injury to the plant ; and consequently 
such variations would not be preserved and perfected. 

Hahenaria hifolia, or Lesser Butterflij Orchis. — I am 
aware that this form and the last are considered by 
Mr. Bentham and by some other botanists as mere 
varieties of one another ; for it is said that intermediate 
gradations in the position of the viscid discs occur. 
But we shall immediately see that the two forms 
differ in a large number of other characters, not to 
mention general aspect and the stations inhabited, with 
which we are not here concerned. Should these two 
forms be hereafter proved to graduate into each other, 
independently of hybridisation, it would be a remarkable 
case of variation ; and I, for one, should be as much 
pleased as surprised at the fact, for these two forms 
certainly differ from one another more than do most 
species belonging to the same genus. 

The viscid discs of the Lesser Butterfly Orchis are 
oval, and face each other. They stand far closer 
together than in the last species ; so much so, that in 
the bud, when their surfaces are cellular, they almost 
touch. They are not placed so low down relatively to 
the mouth of the nectary. The viscid matter is of 
a somewhat different chemical nature, as shown by 
its much greater viscidity, if after having been long 
dried it is moistened, or after being kept in weak 
spirits of wine. The drum-like pedicel can hardly be 
said to be present, but is represented by a longitudinal 
ridge, truncated at the end where the caudicle is 



OPHEE^. 



Chap. IL 



Fig. 12. 




fore-shortened. 
A. Disc and caudicle of //. hi 
full I, seen from above. 



attached, and there is hardly a vestige of the rudi- 
mentary tail. In fig. 12 the discs of both species, 
of the proper proportional 
sizes, are represented as seen 
vertically from above. The 
pollinia, after removal from 
their cells, undergo nearly the 
same movements as in the last 

B. Disc and caudicle of H. chlo- . t i J_^ n ji 

rantha, seen from above, SpCClCS. in both lorms the 

with tiie drum-like pedicel movement is wcll showu by 
removing a pollinium by the 
thick end with a pair of pin- 
cers, and holding it under the microscope, when the 
plane of the viscid disc will be seen to move through 
an angle of at least forty-five degrees. The caudicles 
of the ]^esser Butterfly Orchis are relatively very much 
shorter than in the other species; the little packets 
of pollen are shorter, whiter, and, in a mature flower, 
separate much more readily from one another. Lastly, 
the stigmatic surface is differently shaped, being more 
plainly tripartite, with two lateral prominences, situ- 
ated beneath the viscid discs. These prominences 
contract the mouth of the nectary, making it sub- 
quadrangular. Hence I cannot doubt that the Larger 
and Lesser Butterfly Orchids are distinct species, 
masked by close external similarity.* 

As soon as I had examined the present species. 



* Afconling to Dr. H. Miiller, 
ITabenaria or Platanthera bifoUa 
of Enslish authors is the P. sol- 
stitialis of Boenuinghausen ; and 
lie fully agrees with me that it 
must be ranked as specifically 
distinct from P. chlorantlia. Dr. 
MuUer states tl)at this latter 
species is connected by a series 
of gradalions witJi another form 



which in Germany is called P. 
hifolia. He gives a very full and 
interesting account of the varia- 
bility of these three forms of 
Platanthera, and of their structure 
in relation to their manner of fer- 
tilisation : 'Verhandl. d. Nat. 
Verein. f. Pr. Eh. u. Westfal' 
Jahrg. XXV. III. Folge, v. Bd. pp. 
36-38. 



Chap. II. rLATANTHERA. 75 

I felt convinced, from the position of the viscid discs, 
that it would be fertilised in a different manner from 
the Larger Butterfly Orchis; and now, owing to the 
kindness of Mr. F. Bond, I have examined two moths, 
namely, Agrotis segetum and Anaitis plagiata, one with 
three pollinia, and the other with five pollinia, attached, 
not to the eyes and side of the face as in the last 
species, but to the base of the proboscis. I may 
remark that the pollinia of these two species of Habe- 
naria, when attached to moths, can be distinguished at 
a glance. 

Professor Asa Gray has described* the structure of 
no less than ten American species of Platanthera. 
jMost of them reseml^le in their manner of fertilisation 
the two British species ; but some of the species, in 
which the viscid discs do not stand far apart, have 
curious contrivances, such as a channelled labellum, 
lateral shields, &c., compelling moths to insert their 
proboscides directly in front. P. hooJceri, on the other 
hand, differs in a very interesting manner : the two 
viscid discs stand widely separated from each other ; 
consequently a moth, unless of gigantic size, would be 
able to suck the copious nectar without touching either 
disc ; but this risk is avoided in the following manner : 
— the central line of the stigma is prominent, and the 
labellum, instead of hanging down, as in most of the 
other species, is curved upwards, so that the front of 
the flower is made somewhat tubular and is divided 
into halves. Thus a moth is compelled to go to the 
one or other side, and its face will almost certainly be 
brought into contact with one of the discs. The drum 
of the poUinium, when removed, contracts in tlie 
same manner as I have described under P. chlorantha. 



♦'American Journal of Science,' vol. xxxiv. 18G2, pp. 113, 25f), 
and 424, and vol. xxxvi. 1S63, p. 292. 



76 OPHEE.E. Chap. II. 

Professor Gray lias seen a butterfly (Nisoniades) from 
Canada with a pollinium of this species attached to 
each eye. In the case of P. flava, moths are compelled 
in a different manner to enter the nectary on one side. 
A narrow but strong protuberance, rising from the base 
of the labellum, projects upwards and backwards, so 
as almost to touch the column ; thus the moth, being 
forced to go to either side, is almost sure to withdraw 
one of the viscid discs. P. hijjyerborea and dilatata 
have been regarded by some botanists as varieties of 
the same species; and Professor Asa Gray says that 
he was formerly tempted to come to the same con- 
clusion ; but on closer examination he finds, besides 
other characters, a remarkable physiological difference, 
namely, that P. dilatata, like its congeners, requires 
insect aid and cannot fertilise itself; whilst in P. 
hyperlorea the pollen-masses commonly fall out of the 
anther-cells whilst the flower is very young or in bud, 
and thus the stigma is self-fertilised. Nevertheless, the 
various structures adapted for crossing are still present.* 
The genus Bonatea is closely allied to Habenaria, 
and includes plants having an extraordinary structure. 
Bonatea speciosa is an inhabitant of the Cape of Good 
Hope, and has been carefully described by Mr. Trimen ;t 
but it is impossible to explain its structure without 
drawings. It is remarkable from the manner in which 
the two stigmatic surfaces, as well as the two viscid 
discs, project far out in front of the flower, and from 
the complex nature of the labellum, which consists of 
seven, or probably of nine distinct parts all fused 



* Mr. J. Mansel Weale has de- pollinia not uudei-froing any move- 
scribed (' Journ. Lin. Soc. Bot.* nient or change of position when 
vol. xiii. 1871, p. 47) the method of removed from their cases. 
fertilisation of two South African f ' Journ. Linn. Soc. Bot.* voL 
species of Habenaria : one of ix. 1865, p. 156. 
these is remarkable from the 



CiiAP. II. iJONATEA SPECIOSA- 77 

together. As in Flatantliera flava, there is a process 
at the base of the labellum which compels moths to 
enter the flower on either side. The nectary, accord- 
ing to Mr. Trimen and Mr. J. Mansel Weale, does not 
contain free nectar ; but the latter author believes 
that the tissue of which it is composed tastes sweet, so 
that moths probably penetrate it for the sake of the 
intercellular fluid. The pollinia are of astonishing 
length, and when removed from their cases hang down 
merely from the weight of the pollen-masses, and if 
attached to the head of an insect would be in a proper 
position for adhering to the stigma. Mr. Weale has 
likewise described some other South African species 
of Bonatea.* These differ from B. speciosa in having 
their nectaries full of nectar. He found a small 
butterfly, Fyrgus elmo, " perfectly embarrassed by the 
number of pollinia of this Bonatea attached to its 
sternum." But he does not specify whether the 
sternum was naked or covered with scales. 

The South African genera Disa and Disperis are 
placed by Lindley in two sub-tribes of the Ophrese. 
The superb flowers of Disa grandiflora have been 
described and figured by Mr. Trimen.t The posterior 
sepal, instead of the labellum, is developed into a large 
nectary. In order that insects may reach the copiously 
stored nectar, they must insert their proboscides on 
either side of the column; and in accordance with 
this fact the viscid discs are turned outwards in an 
extraordinary manner. The pollinia are crooked, and 
when removed bend downwards from their own weight, 
so that no movement is necessary for placing themselves 
in a proper position. Considering the large supply of 

• * Joum. Linn. Soc. Bot.* vol. t * Journ. Linn. Soe. Bot.' vol. 

X. p. 470. vii. 1863, p. 144. 



78 OPHRE^. Chap.il 

nectar and that the flowers are very conspicuous, it 
is remarkable that they are rarely visited by insects. 
Mr. Trimen wrote to me in 1864 that he had lately 
examined seventy-eight flowers, and only twelve of 
these had one or both pollinia removed by insects, 
and only five had pollen on their stigmas. He does 
not know what insects occasionally fertilise the flowers ; 
but Mrs. Barber has more than once seen a large fly, 
allied to Bombylius, with the pollinia oiBisa polygnoides 
attached to the base of its proboscis. Mr. Weale states* 
that D. macrantha differs from D. grandiflora and earnuta 
in producing plenty of seed, and is remarkable from 
often fertilising itself. This follows from " a very slight 
jerk, when the flower is fully expanded, sufficing to 
eject the pollinia from their widely open anther-cases, 
and to bring them into contact with the stigma. 
This in nature is not unseldom the case, as I have 
repeatedly found many flowers thus fertilised." He 
has, however, no doubt that the flowers are likewise 
cross-fertilised by nocturnal insects. He adds that 
D. grandiflora in being so seldom fertilised by insects 
off'ers a case like that of Oplirijs muscifera ; w^hilst 
D. macrantha in being often self-fertilised closely cor- 
responds with Ophrijs apifera ; but this latter species 
seems to be invariably self-fertilised. 

Lastly, Mr. Weale has described,! as far as he could 
make out, the manner in which a species of Disperis 
is fertilised by the aid of insects. It deserves notice 
that the labellum and two lateral sepals of this plant 
secrete nectar. 

We have now finished with the Ophre?e ; but before 
passing on to the following tribes, I will recapitulate 

* ' Jonrn. Linn. Soc. Bot.' vol. t * Jomn. Linn Soc. Bot.* vol. 

xiii. 1871. p. 4.^. xiii. 187L p. 42. 



Chap. II. OPPREiE. 79 

the chief facts with respect to the movements of the 
pollinia, all due to the nicely regulated contraction of 
that small portion of membrane (together with the 
pedicel in the case of Habenaria) lying between the 
layer or ball of adhesive matter and the extremity of 
the caudicle. In a few cases, however, as with some 
of the species of Disa and Bonatea, the caudicles when 
removed from their cells do not undergo any movement ; 
the weight of the pollen-masses sufScing to depress 
them into a proper position. In most of the species of 
Orchis the stigma lies directly beneath the anther-cells, 
and the pollinia simply move vertically downwards. 
In Orchis pyramidalis there are two lateral and inferior 
stigmas, and the pollinia move downwards and outwards, 
diverging to the proper angle, so as to strike the two 
lateral stigmas. In Gymnadenia the pollinia move 
only downwards, but they are adapted for striking the 
lateral stigmas, by being attached to the upper lateral 
surfaces of the proboscides of Lepidoptera. In Nigri- 
tella they move upwards, but this depends merely on 
their being always affixed to the lower side of the 
proboscis. In Habenaria the stigmatic surface lies 
beneath and between the two widely-separated anther- 
cells, and the pollinia here converge, instead of diverg- 
ing as in Orchis pyramidalis, and likewise move down- 
wards. A poet might imagine that whilst the pollinia 
were borne through the air from flower to flower, 
adhering to an insect's body, they voluntarily and 
eagerly placed themselves in that exact position, in 
which alone they could hope to gain their wish and 
perpetuate their race. 



80 AEETHUSE^ Chap. IIL 



CHAPTEK IIL 

AEETHUSE^. 

Cephalanthera grandiflora ; rostellum aborted ; early penetration of the 
pollen-tubes; case of imperfect self-fertilisation ; cross-fertilisation 
effected by insect^i which gnaw the labellum — Cephalanthera ensi- 
folia — Pogonia— Pterostylis and other Austialian orchids with the 
labellum sensitive to a touch — Vanilla— Sobraha. 

Cephalanthera grandiflora, — This Orchid is remark- 
able from not possessing a rostellum, which is so 
eminently characteristic of the order. The stigma is 
large, and the anther stands above it. The pollen 
is extremely friable and readily adheres to any object. 
The grains are tied together by a few weak elastic 
threads ; but they are not cemented together, so as to 
form compound pollen-grains, as in almost all other 
Orchids.* In this latter character and in the complete 
abortion of the rostellum we have evidence of degrada- 
tion ; and Cej)halanthera appears to me like a degraded 
Epipactis, a member of the Neottese, to be described in 
the next chapter. 

The anther opens whilst the flower is in bud and 
partly expels the pollen, which stands in two nearly 
free upright pillars, each nearly divided longitudinally 
into halves. These subdivided pillars rest against or 
even overhang the upper square edge of the stigma, 
which rises to about one- third of their height (see front 



♦ This separation of the grains by Lindley in hi's magnificent 
was ob.served, and is represented, ' Illustrations of Orchidaceous 
by Bauer in the plate published Plants.' 



Chap. III. CEPHALANTHERA GRANDIFLORA. 



81 



view B, and side view C, in fig. 13). Whilst the flower 
is still in bud, the pollen-grains which rest against the 
upper sharp edge of the stigma (but not those in the 
upper or lower parts of the mass) emit a multitude of 






B 



Cephalanthera. graxdiflora. 



anther; in the front view, B, 
the two cells with the included 
pollen are seen. 

one of the two lateral rudimen- 
tary anthers, or auricles. 

masses of pollen. 

stigma. 

distal portion of the labellum. 



A. Oblique view of perfect flower, 
when fully expanded. 

B. Front view of column, with all 
the petals and sepals removed. 

C. Side view of column, with all the 
sepals and petals removed ; the 
narrow pillars of pollen (p) 
between the anther and stigma 

] can just be seen. 

tubes ; and these deeply penetrate the stigmatic tissue. 
After this period the stigma bends a little forward, and 
the result is that the two friable pillars of pollen are 
drawn a little forward and stand almost completely free 

4147 



82 ARETliUSE^. Chap. IIL 

from the anther-cells, being tied to the edge of the 
stigma and supported by the penetration of the pollen- 
tubes. AVithout this support the pillars would soon fall 
down. 

The flower stands upright, with the lower part of 
the labellum turned up parallel to the column (fig. A). 
The tips of the lateral petals never become separated ; * 
so that the pillars of pollen are protected from the 
wind, and as the flower stands upright they do not 
fall down from their own weight. These are points of 
much importance to the plant, as otherwise the pollen 
would have been blown or fallen down and been 
wasted. The labellum is formed of two portions ; when 
the flower is mature, the small triangular distal portion 
turns down at right angles to the basal portion ; and 
thus offers a small landing-place for insects in front 
of the triangular entrance, situated half-way up the 
almost tubular flower. After a short time, as soon as 
the flower is fully fertilised, the small distal portion 
of the labellum rises up, shuts the triangular door, and 
again perfectly encloses the organs of fructification. 

Although I have often searched for nectar within the 
cup of the labellum, I have never found even a trace. 
The terminal portion of the labellum is frosted with 
globular papillae of an orange colour, and within the 
cup there are several transversely wrinkled, longi- 
tudinal ridges of a darker orange tint. These ridges 
are often gnawed by some animal, and I have found 
minute, bitten-off fragments lying within the base of the 
cup. In the summer of 1862 the flowers were visited 
less frequently by insects than is usual, as shown by 
the unbroken state of the pollen-masses ; nevertheless, 



* Bauer fif^nres the flowers say is that I have not seen them 
much more widely expande 1 than in this condition. 
is here represented : all that I can 



Chaf. III. CEPHALANTHERA GEANDIFLOKA. 83 

out of seventeen flowers which were examined one day^ 
five had their ridges gnawed, and on the next day, 
seven out of nine other flowers were in this state. As 
there was no appearance of slime, I do not believe 
that they had been attacked by slugs; but whether 
they had been gnawed by winged insects, which alone 
would be effectual for cross-fertilisation, I know not. 
The ridges had a taste like that of the labellum of 
certain Vandeae, in which tribe (as we shall hereafter 
see) this part of the flower is often gnawed by insects. 
Cephalanthera is the only British Orchid, as far as I 
have observed, which attracts insects, by thus ofiering 
to them solid food. 

The early penetration of the stigma by a multitude 
of pollen-tubes, which were traced far down the stigmatic 
tissue, apparently gives us another case, like that of the 
Bee Ophrys, of perpetual self-fertilisation. I was much 
surprised at this fact, and asked myself : Why does the 
distal portion of the labellum open for a short period ? 
what is the use of the great mass of pollen above and 
below that layer of grains, the tubes of which alone 
penetrate the upper edge of the stigma ? The stigma 
has a large flat viscid surface ; and during several years 
I have almost invariably found masses of pollen adher- 
ing to its surface, and the friable pillars by some means 
broken down. It occurred to me that, although the 
flowers stand upright, and the pillars are well pro- 
tected from the wind, yet that the pollen-masses might 
ultimately topple over from their own weight, and so 
fall on the stigma, thus completing the act of self-fer- 
tilisation. Accordingly, I covered with a net a plant 
having four buds, and examined the flowers as soon as 
they had withered ; the broad stigmas of three of them 
were perfectly free from pollen, but a little had fallen 
on one corner of the fourth. AVith the exception of 



8-4 iLEETHUSE^. Chap. III. 

the summit of one pillar in this latter flower, all the 
other pillars still stood upright and unbroken. I looked 
at the flowers of some surrounding plants, and every- 
where found, as I had so often done before, broken-down 
pillars and masses of pollen on the stigmas. 

From the usual state of the pillars of pollen, as 
well as from the gnawed condition of the ridges on the 
labellum, it may be safely inferred that insects of some 
kind visit the flowers, disturb the pollen, and leave 
masses of it on the stigmas. We thus see that the 
turning down of the distal portion of the labellum, by 
which a temporary landing-place and an open door are 
afforded,— the upturned labellum, by which the flower 
is made tubular so that insects are compelled to crawl 
close by the stigmatic surface, — the pollen readily 
cohering to any object, and standing in friable pillars 
protected from the wind, — and, lastly, the large masses 
of pollen above and below that layer of grains, the 
tubes of which alone penetrate the edge of the stigma, — 
are all co-ordinated structures, far from useless ; and 
they would be quite useless if these flowers were always 
self- fertilised. 

To ascertain how far the early penetration of the 
upper edge of the stigma by the tubes of those grains 
which rest on it, is effectual for fertilisation, I covered 
up a plant, just before the flowers opened, and removed 
the thin net as soon as they had begun to wither. From 
long experience I am sure that this temporary cover- 
ing could not have injured their fertility. The four 
covered flowers produced seed-capsules as fine in ap- 
pearance as those on any of the surrounding plants. 
When ripe, I gathered them, and likewise capsules 
from several of the surrounding plants, growing under 
similar conditions, and weighed the seed in a chemical 
balance. The seeds from the four capsules on the 



Chap. IIP. CEPHALANTHERA GRANDIFLORA. 85 

uncovered plants weighed 1 • 5 grain ; whilst those 
from an equal number of capsules on the covered plant 
weighed under 1 grain ; but this does not give a fair 
idea of the relative difference of their fertility, for I 
observed that a great number of the seeds from the 
covered plant consisted of minute and shrivelled husks. 
Accordingly I mixed the seeds well together, and took 
four little lots from one heap and four little lots from 
the other heap, and, having soaked them in water, com- 
pared them under the microscope : out of forty seeds 
from the uncovered plants there were only four bad 
ones, whereas out of forty seeds from the covered-up 
plants there were at least twenty-seven bad ; so that 
there were nearly seven times as many bad seeds from 
the covered plants, as from those left free to the access 
of insects. 

We may therefore cor- elude that this orchid is 
constantly self-fertilised, although in a very imperfect 
manner ; but this would be highly useful to the plant, 
if insects failed to visit the flowers. The penetra- 
tion of the pollen-tubes, however, is apparently even 
more serviceable by retaining the pillars of pollen in 
their proper places, so that insects, in crawling into the 
flowers, may get dusted with pollen. Self-fertilisation 
also may, perhaps, be aided by insects, carrying pollen 
from the same flower on to the stigma ; but an insect 
thus smeared with pollen could hardly fail likewise to 
cross the flowers on other plants. From the relative 
position of the parts, it seems indeed probable (but I 
omitted to prove this by the early removal of the 
anthers, so as to observe whether pollen was brought 
to the stigma from other flowers) that an insect would 
more frequently get dusted by crawling out of a flower 
than by crawling into one ; and this would of course 
facilitate a cross between distinct individuals. Hence 



86 ARETHUSE.E. Chap. III. 

Cephalanthera offers only a partial exception to the 
rule that the flowers of Orchids are generally fertilised 
by pollen from another plant. 

Cephalanthera ensifolia. — According to Delpino,* the 
flowers of this species are visited by insects, as shown 
by the removal of the pollen-masses. He believes that 
this is effected by their bodies being first rendered sticky 
by means of the stigmatic secretion. It is not clear 
whether the flowers also fertilise themselves. Each 
pollen-mass is divided into two, instead of being merely 
sub-divided, so that there are four distinct pollen-masses. 

Pogonia ophioglossoides. — The flowers of this plant, 
an inhabitant of the United States, resemble, as 
described by Mr. Scudder, f those of Cephalanthera in 
not having a rostellum, and in the pollen-masses not 
being furnished with caudicles. The pollen consists of 
powdery grains not united by threads. Self-fertilisation 
seems to be effectually prevented ; and the flowers on 
distinct plants must intercross, for each plant generally 
bears only a single flower. 

Fterostylis trullifolia and lo7igifolia. — I may here 
briefly mention some Orchids, inhabitants of Australia 
and New Zealand, which are included by Lindley in 
the same family of the Arethusese with Cephalanthera 
and Pogonia, and are remarkable from their labella 
being extremely sensitive or irritable. Two of the 
petals and one of the sepals form a hood which encloses 
the column, as may be seen at A in the accompanying 
figure of Fterostylis longifolia. 

The distal portion of the labellum affords a landing- 
place for insects, in nearly the same manner as with 
Cephalanthera; but when this organ is touched it 
rapidly springs up, carrying with it the touching insect, 

* • Ult. Osservaz. sulla Dico- f ' Proe. Boston Soc. Nat. Hi&t.* 

gamia,' pail ii. 1875, p. 149. vol. ix. 1863, p. 182. 



Chap. III. 



PTEEOSTYLIS LONGIFOLIA. 



87 



which is thus temporarily imprisoned within the other- 
wise almost completely closed flower. The labellum 



Fi2. 14. 




Pterostylis longifoLia. (Copied from Mr. R. D. Fitzgerald's * Australian 
Orchids.') 



A. Flower in its natural state: the 

outline of the column is dimly- 
seen within. 

B. Flower with the near lateral 

petal removed, showing the 



column with its two shields, 
and the labellum in the position 
which it occupies after having 
been touched 



remains shut from half an hour to one hour and a 
half, and on reopening is again sensitive to a touch. 
Two membranous shields project on each side of the 



88 AKETIIUSEJE. Chap. HI. 

upper part of the column, with their edges meeting 
in front, as may be seen in fig. B. In this drawing 
the petal on the near side has been cut away, and 
the labellum is represented in the position which it 
assumes after having been touched. As soon as the 
labellum has thus risen, an imprisoned insect cannot 
escape except by crawling through the narrow passage 
formed by the two projecting shields. In thus escaping 
it can hardly fail to remove the poUinia, as, before 
coming into contact with them, its body will have been 
smeared with the viscid matter of the rostellum. On 
being imprisoned in another flower, and on again escap- 
ing by the same passage, it will almost certainly leave 
at least one of the four pollen-masses on the adhesive 
stigma, and thus fertilise the flower. 

All that I have here said is taken from the admir- 
able description given by Mr. Cheeseman * of Pterostylis 
trullifolia ; but I have copied the figure of P. longifolia 
from Mr. Fitzgerald's great work on the Australian 
Orchids, as it shows plainly the relation of all the parts. 

Mr. Cheeseman placed insects within several flowers 
of P. truUifolia, and saw them afterwards crawl out, 
generally with pollinia attached to their backs. He 
also proved the importance of the irritable labellum 
by removing it from twelve flowers whilst yonng, and 
in this case insects which entered the flowers would not 
have been compelled to crawl out through the passage ; 
and not one of these flowers produced a capsule. The 
flowers seem to be frequented exclusively by Diptera ; 
but what attraction they present is not known, as they 
do not secrete nectar. Mr. Cheeseman believes that 
hardly a quarter of the flowers prod\ice capsules ; not- 
withstanding that on one occasion he examined 110 

♦ * Transact. New Zealand Institute,' vol. v. IS73, p 352 ; and vol. 
fii. p. 351. 



CuAP. III. PTEROSTYLIS LONGIFOLIA. 89 

flowers in a withered condition, and seventy-one of these 
had pollen on their stigmas, and only twenty-eight had 
all four pollinia still within their anthers. All the 
New Zealand species bear solitary flowers, so that dis- 
tinct plants cannot fail to be intercrossed. I may add 
that Mr. Fitzgerald also placed a small beetle on the 
labellum of P. longifolia^ which was instantly carried 
into the flower and imprisoned ; afterwards he saw 
it crawl out with two pollinia attached to its back. 
Nevertheless he doubts, from reasons which seem to 
me quite insufficient, whether the sensitiveness of the 
labellum is not as great a disadvantage as an advan- 
tage to the plant. 

Mr. Fitzgerald has described another Orchid belong- 
ing to the same sub-tribe, Ccdadenia dimorpha, which 
has an irritable labellum. He kept a plant in his room, 
and says : " A house-fly lighting on the lip was carried 
by its spring against the column, and becoming en- 
tangled in the gluten of the stigma, and struggling to 
escape, removed the pollen from the anther and smeared 
it on the stigma." He adds, " Without some such aid 
the species of this genus never produce seed." But 
from the analogy of other Orchids we may feel sure 
that insects usually behave very differently from the 
fly which he saw caught on the stigma, and no doubt 
they carry the pollen-masses from plant to plant. The 
labellum of another Australian genus, Calrena, one oi 
the Arethusese, is said by Dr. Hooker * to be irritable ; 
so that when touched by an insect it shuts up suddenly 
against the column, and temporarily encloses its prey 
as it were within a box. The labellum is covered by 
curious papillae, which, as far as Mr. Fitzgerald has 
seen, are not gnawed by insects. 



Flora of Tasmatiia,* vol. ii. p. 17. 



90 AKETHUSE^. Chap. Ill 

Mr. Fitzgerald describes and figures several other 
genera, and states with respect to Acianthus fornicatus 
and exsertus that neither species produce seeds if 
protected from insects, but are easily fertilised by 
pollen placed on their stigmas. Mr. Cheeseman * has 
witnessed the fertilisation of Acianthus sinclairii in 
New Zealand, the flowers of which are incessantly 
visited by Diptera, without whose aid the pollinia are 
never removed. Out of eighty-seven flowers borne 
by fourteen plants, no less than seventy-one matured 
capsules. This plant according to the same observer 
exhibits one remarkable peculiarity, namely, that the 
pollen-masses are attached to the rostellum by means 
of the exserted pollen-tubes, which serve as a caudicle ; 
and the pollen-masses are thus removed together with 
the rostellum, which is viscid, when the flowers are 
visited by insects. The flowers of the allied Cyrto- 
stylis are also much frequented by insects, but the 
pollinia are not so regularly removed as those of the 
Acianthus ; and with Corysanthes, only five out of 200 
flowers produced capsules. 

The Vanillidse according to Lindley form a sub- 
tribe of the Arethusese. The large tubular flowers of 
Vanilla aromatica are manifestly adapted to be ferti- 
lised by insects ; and it is known that when this plant 
is cultivated in foreign countries, for instance in Bour- 
bon, Tahiti, and the East Indies, it fails to produce 
its aromatic pods unless artificially fertilised. This 
fact shows that some insect in its American home is 
specially adapted for the work ; and that the insects 
of the above-named tropical regions, where the Yanilla 
flourishes, either do not visit the flowers, though they 
secrete an abundance of nectar, or do not visit them 



* ' Transact. New Zealand Institute,* vol. vii. 1875, p. 843. 



Chap. III. PTEROSTYLIS LONGIFOLIA. 91 

in the proper manner.* I will mention only two pecu- 
liarities in the structure of the flowers : the anterior 
part of the pollen-masses is semi-waxy and the posterior 
part somewhat friable ; the grains are not cemented 
together into compound grains, and the single grains 
are not united by fine elastic threads but by viscid 
matter; this matter would aid in causing the pollen 
to adhere to an insect, but I should have thought that 
such aid was superfluous, as the viscid rostellum is 
well developed. The other peculiarity is that the 
labellum, in front of the stigma, and some way beneath 
it, is furnished with a stiff hinged brush, formed of a 
series of combs one over the other, which point down- 
wards. This structure would allow an insect to crawl 
easily into a flower, but would compel it whilst re- 
treating to press close against the column ; and in 
doing so it would remove the pollen-masses, leaving 
them on the stigma of the next flower which was 
visited. 

The genus Sobralia is allied to Vanilla, and Mr. 
Cavendish Browne informs me that he saw a large 
humble-bee enter a flower of S. macrantha in his 
hothouse, and when it crawled out it had the two 
large pollen- masses firmly fixed to its back, nearer to 
the tail than to the head. The bee then looked about, 
and seeing no other flower re-entered the same one of 



* For Bmibon see 'Bui. Soc. in the Blue Mountains of New 
Bot. de France,' torn. i. 18f»4. p. South Wiiles; removed from 
290. For Tahiti see H. A. Tilley, theiiee to Sydney, a number of 
'Japan, the Amour, &o./ 1861, p. plants, though {iowerinj? well, have 
375. For the East Indies tee not borne any seed if left to them- 
Morren in 'Annals and Mag. of selves, though invariably fertile 
Nat. Hist.' 1839, vol. iii. p. 6. I when the pollen-masses were re- 
may give an analogous but more moved and placed on the stigma." 
striking case from Mr Fitzgerald, Yet the Blue Mountains are less 
who says "that Sarcochilus par- than one hundred miles dibtaiit 
vijlorus (one of the Vandeae) pro- fiom Sydney, 
duces capsules not unfrequently 



92 AEETHUSE^. CflAP. III. 

the Sobralia, but quickly retreated, leaving the pollen- 
masses on the stigma, with the viscid discs alone 
adhering to its back. The nectar of this Guatemala 
Orchid seemed too powerful for our British bee, for it 
stretched out its legs and lay for a time as if dead on 
the labellum, but afterwards recovered. 



Chap. IV. EPIPACTIS PALUSTEIS. 93 



CHAPTER IV. 

NEOTTE^. 

Epipactis palustris ; curious shape of the labellura and its importance 
ill the fructification of the flower— Other species of Epipactis — 
Epipogiiira — Goodyera repens — Sjuranthes autumnalis; perfect 
adapt ition by which the pollen of a younger flower is carried to the 
stigma of an older flower on another plant— Listera ovata ; sensi- 
tiveness of the rostellum; explosion of viscid matter; action of 
insects ; perfect adaptation of the several organs — Listera cordata — 
Ncottia nidus-avis ; its fertilisation efiected in the same manner as 
in Listera — Thelymitra, self-fertile. 

We have now arrived at a third tribe, the Neottene of 
Lindley, which includes several British genera. These 
present many interesting points with respect to their 
strncture and manner of fertilisation. 

The Neottese have a free anther standing behind the 
stigma. Their pollen-grains are tied together by fine 
elastic threads, which partially cohere and project at 
the upper end of the pollen-mass, being there attached 
(with some exceptions) to the back of the rostellum. 
Consequently the pollen-masses have no true and dis- 
tinct caudicles. In one genus alone (Goodyera) the 
pollen-grains are collected into packets as in Orchis. 
Epipactis and Goodyera agree pretty closely in their 
manner of fertilisation with the Ophreae, but are more 
simply organised. Spiranthes comes under the same 
category, but has been differently modified in some 
respects. 

Epipactis palustris* — The lower part of the large 



* I am much indebted to INIr. ing me frosh specimens of thi 
A. G. ]Mnre, of Bembridge. in the beautiful Orchis. 
I>le of Wight, for repeatedly send- 



94 




Chap. IV. 



EpIPACI'IS PALUSTRI8. 



a. anther, with the two open cells 
seen in the front view D. 

a', rudin.entary anther, or auricle, 
referred to in a future chapter. 

r. rostellum. 

s. stigma. 

l. labellum. 

A. Side view of flower, with the 

lower sepals removed, in its 
natural position. 

B. Side view of flower, with the 

distal portion of the labellum 
depressed, as if by the weight 
of an insect. 

C. Side view c f flower, somewhat 



enlarged, with all the sepals 
and petals removed, excepting 
the labellum, of which the 
near side has been cut away ; 
the massive anther is seen to 
be of large size. 
D. Front view of column, somewhat 
enlarged, with all the sepals 
and petals removed: the ros- 
tellum has sunk down a little 
in the specimen figured, and 
ought to have stood higher, 
so as to hide more of the 
anther-cells. 



Chap. IV. EPIPACTIS PALUSTRIS. 95 

stigma is bilobed and projects in front of the column 
(see s in the side and front views, C, J), fig. 15). On 
its square summit a single, nearly globular rostellum 
is seated. The anterior face of the rostellum (r, C, D) 
projects a little beyond the surface of the upper part of 
the stigma, and this is of importance. In the early bud 
the rostellum consists of a friable mass of cells, with the 
exterior surface rough : these superficial cells undergo 
a great change during development, and become con- 
verted into a soft, smooth, highly elastic membrane or 
tissue, so excessively tender that it can be penetrated 
by a human hair; when thus penetrated, or when 
slightly rubbed, the surface becomes milky and in some 
degree viscid, so that the pollen-grains adhere to it. 
In some cases, though I observed this more plainly in 
E]pi][)aGtis latifolia, the surface of the rostellum appa- 
rently becomes milky and viscid without having been 
touched. This exterior soft elastic membrane forms 
a cap to the rostellum, and is internally lined with a 
layer of much more adhesive matter, which, when ex- 
posed to the air, dries in from five to ten minutes. 
By a slight upward and backward push with any object, 
the whole cap, with its viscid lining, is removed with 
the greatest ease ; a minute square stump, the basis 
of the rostellum, being alone left on the summit of the 
stigma. 

In the bud-state the anther stands quite free behind 
the rostellum and stigma; it opens longitudinally 
whilst the flower is still unexpanded, and exposes the 
two oval pollen-masses, which now lie loose in their 
cells. The pollen consists of spherical granules, co- 
hering in fours, but not affecting each other's shapes : 
and these compound grains are tied together by fine 
elastic threads. The threads are collected into bundles 
extending longitudinally along the middle line of the 



96 NEOTTE.E. Chap. IV 

front of each pollinium, where it comes into contact 
with the back of tne uppermost part of the rostellum. 
From the number of these threads this middle line 
looks browTi, and each pollen-mass here shows a 
tendency to divide longitudinally into halves. In all 
these respects there is a close general resemblance to 
the poUinia of the Ophrese. 

The line where the parallel threads are the most 
numerous is the line of greatest strength ; elsewhere 
the pollen-masses are extremely friable, so that large 
portions can easily be broken off. In the bud-state 
the rostellum is curved a little backwards, and is 
pressed against the recently-opened anther ; and the 
above-mentioned slightly projecting bundles of threads 
become firmly attached to the posterior flap of the 
membranous cap of the rostellum. The point of attach- 
ment lies a little beneath the summit of the pollen- 
masses ; but the exact point is somewhat variable, for 
I have met with specimens in which the attachment 
was one-fifth of the length of the pollen-masses from 
their summits. This variability is so far interesting, 
as it is a step leading to the structure of the Ophrese, 
in which the confluent threads, or caudicles, always 
spring from the lower ends of the pollen-masses. After 
the pollinia are firmly attached by their threads to 
the back of the rostellum, the rostellum bends a little 
forwards, and this partly draws the pollinia out of the 
anther-cells. The upper end of the anther consists of a 
blunt, solid point, not including pollen ; this blunt point 
projects slightly beyond the face of the rostellum, 
which circumstance, as we shall see, is important. 

The flowers stand out (fig. A) almost horiozontally 
from the stem. The labellum is curiously shaped, as 
may be seen in the drawings : the distal half, which 
projects beyond the other petals and forms an excellent 



Chai'. IV. EPIPACTIS PALUSTPvIS. 97 

landing-place for insects, is joined to the basal half by 
a narrow hinge, and naturally (fig. A) is turned a little 
upwards, so that its edges pass within the edges of the 
basal portion. So flexible and elastic is the hinge that 
the weight of even a fly, as Mr. More informs me, 
depresses the distal portion ; it is represented in fig. B 
in this state ; but when the weight is removed it 
instantly springs up to its former position (fig. A), and 
with its curious medial ridges partly closes the entrance 
into the flower. The basal portion of the labellum forms 
a cup, which at the proper time is filled with nectar. 

Now let us see how all the parts, which I have been 
obliged to describe in detail, act. When I first ex- 
amined these flowers I was much perplexed : trying in 
the same manner as I should have done with a true 
Orchis, I slightly pushed the protuberant rostellum 
downwards, and it was easily ruptured ; some of the 
viscid matter was withdrawn, but the pollinia remained 
in their cells. Reflecting on the structure of the 
flower, it occurred to me that an insect in entering one 
in order to suck the nectar, would depress the distal 
portion of the labellum, and consequently would not 
touch the rostellum ; but that, when within the flower, 
it would be almost compelled, from the springing up 
of this distal half of the labellum, to rise a little up- 
wards and back out parallel to the stigma. I then 
brushed the rostellum lightly upwards and backwards 
with the end of a feather and other such objects ; and 
it was pretty to see how easily the membranous cap 
of the rostellum came off, and how well from its elas- 
ticity it fitted any object, whatever its shape might be, 
and how firmly it clung to the object owing to the 
viscidity of its under surface. Large masses of pollen, 
adhering by the elastic threads to the cap of the ros- 
tellum were at the same time withdrawn. 



98 NEOTTE.E. CiiAK IV. 

Nevertheless the pollen-masses were not removed 
nearly so cleanly as those which had been naturally 
removed by insects. I tried dozens of flowers, always 
with the same imperfect result. It then occurred to 
me, tliat an insect in backing out of the flower would 
naturally push with some part of its body against the 
blunt and projecting upper end of the anther, which 
overhangs the stigmatic surface. Accordingly I so 
held a brush that, whilst brushing upwards against the 
rostellum, I pushed against the blunt solid end of the 
anther (see flg. C) ; this at once eased the pollinia, and 
they were withdrawn in an entire state. At last I 
understood the mechanism of the flower. 

The large anther stands above and behind the 
stigma, forming an angle with it (fig. C), so that the 
pollinia when withdrawn by an insect would adhere 
to its head or body in a position fitted to strike the 
sloping stigmatic surface as soon as another flower 
was visited. Hence we have not here, or in any of 
the Neottese, that movement of depression so common 
with the pollinia of the Ophreae. When an insect 
with the pollinia attached to its back or head enters 
another flower, the easy depression of the distal portion 
of the labellum probably plays an important part ; for 
the pollen-masses are extremely friable, and if they 
were struck against the tips of the petals much of the 
pollen would be lost ; but as it is, an open gangway 
is offered, and the viscid stigma, with its lower pro- 
tuberant part lying in front, is the first object against 
which the pollen -masses projecting forwards from the 
insect's head or back would naturally strike. I may 
add that in one large lot of flower-spikes, a great 
majority of the pollinia had been naturally and 
cleanly removed. 

In order to ascertain m hether I was right in believing 



Chap. IV. EPIPACTIS rALUSTlUS. 99 

tliat the distal hinged portion of the labellum was of 
importance in the fertilisation of the flowers, I asked 
Mr. More to remove this part from some young flowers, 
and to mark them. He tried the experiment on eleven 
flowers, three of which did not produce seed-capsules; 
but this may have been accidental. Of the eight 
capsules which were produced, two contained about as 
many seeds as those from unmutilated flowers on the 
same plant ; but six capsules contained much fewer 
seeds. Most of the seeds were well-formed. These 
experiments, as far as they go, support the view that 
the distal part of the labellum is of importance in 
causing insects to enter and leave the flowers in the 
best manner for their fertilisation. 

Since the appearance of the first edition of this book, 
my son William has observed for me this Epipactis in 
the Isle of Wight. Hive-bees seem to be the chief 
agents in fertilisation ; for he saw them visit about a 
score of flowers, and many had pollen-masses attached 
to their foreheads, just above the mandibles. I had 
supposed that insects always crawled into the flowers ; 
but hive-bees are too large to do this; they always 
clung, whilst sucking the nectar, to the distal and 
hinged half of the labellum, which was thus pressed 
downwards. Owing to this part being elastic and 
tending to spring up, the bees, as they left the flowers, 
seemed to fly rather upwards ; and this favoured, in 
the manner previously explained, the complete with- 
drawal of the pollen-masses, quite as well as if the 
insects had crawled, in an upward direction, out of 
the flower. Perhaps the upward movement may not 
be so necessary in all cases as I had supposed ; for, 
judging from the manner in which the pollen-masses 
were attached to the hive-bees, the back part of their 
heads could hardly fail to press against and lift up the 



LOO NEOTTEiE. Chap. IV. 

blunt, solid, upper end of the anther, thus freeing the 
pollen-masses. Various other insects besides hive-bees 
visit the flowers. My son saw several large flies (Sar- 
cophaga carnosa) haunting them; but they did not 
enter in so neat and regular a manner as the hive-bees ; 
nevertheless two had pollen-masses attached to their 
foreheads. Several smaller flies (Coelojja frigida) were 
also seen entering and leaving the flowers, with pollen- 
masses adhering rather irregularly to the dorsal surface 
of the thorax. Three or four distinct kinds of Hymen- 
optera (one of small size being Crabro hrevis) likewise 
visited the flowers ; and three of these Hymenoptera 
had pollen-masses attached to their backs. Other still 
more minute Diptera, Coleoptera, and ants w^ere seen 
sucking the nectar ; but these insects appeared to be 
too small to transport the pollen-masses. It is re- 
markable that some of the foregoing insects should 
visit the flowers ; for Mr. F. Walker informs me that 
the Sarcophaga frequents decaying animal matter, and 
the Ccelopa haunts seaweed, occasionally settling on 
flowers. The Crabro also, as I hear from Mr. F. Smith, 
collects small beetles (Halticae) for provisioning its 
nest. It is equally remarkable, seeing how many 
kinds of insects visit this Epipactis, that although my 
son watched hundreds of plants for some hours on three 
occasions, not a single humble-bee alighted on a flower, 
though many were flying about. 

Epipactis latifolia, — This species agrees with the 
last in most respects. The rostellum, however, projects 
considerably further beyond the face of the stigma, 
and the blunt upper end of the anther less so. The 
viscid matter lining the elastic cap of the rostellum 
takes a longer time to get dry. The upper petals and 
sepals are more widely expanded than in E. palustris : 
the distal portion of the labellum is smaller, and is 



Chap. IV. EPIPACTIS LATIFOLIA. 101 

firmly united to the basal portion (fig. 16), so that it 
is not flexible and elastic ; it apparently serves only as 
a landing-place for insects. The fertilisation of this 
species depends simply on an insect striking in- an 
upward and backward direction the highly-protuberant 
rostellum, which it would be apt to do when retreating 
from the flower after having sucked the copious nectar 

Fi?. 16. 



EpIPACTIS LATIFOLIA. 

Flower viewed sideways, with all the sepals and petals removed, except the 
label lum. 

a. anther. I s. stigma. 

r. rostellum. ' /. labellum. 

in the cup of the labellum. Apparently it is not at 
all necessary that the insect should push upwards the 
blunt upper end of the anther ; at least I found that 
the pollinia could be removed easily by simply drag- 
ging off the cap of the rostellum in an upward or 
backward direction. 

As some plants grew close to my house, I have been 
able to observe here and elsewhere their manner of 
fertilisation during several years. Although hive-bees 
and humble-bees of many kinds were constantly flying 
over the plants, I never saw a bee or any Dipterous 
insect visit the flowers ; but in Germany Sprengel 
caught a fly with the pollinia of this plant attached 
to its back. On the other hand I have repeatedly 



102 NEOTTEiE. Chap. IV. 

observed the common wasp (Vespa si/Ivestris) sucking 
the nectar out of the open cup-shaped labellum. I 
thus saw the act of fertilisation effected by the pollen- 
masses being removed by the wasps, and afterwards 
carried attached to their foreheads to other flowers. 
Mv. Oxenden also informs me that a large bed of 
E. purpurafa (which is considered by some botanists to 
be a distinct species, and by others a variety) was fre- 
quented by " swarms of wasps." It is very remarkable 
that the sweet nectar of this Epipactis should not be 
attractive to any kind of bee. If wasps were to become 
extinct in any district, so probably would the Epipactis 
latifolia. 

To show how effectually the flowers are fertilised, I 
may add that during the wet and cold season of 1860 a 
friend in Sussex examined five spikes bearing eighty-five 
expanded flowers ; of these, fifty-three had the pollinia 
removed, and thirty-two had them in place : but as 
many of the latter were immediately beneath the buds, 
a larger number would almost certainly have been 
afterwards remowed. In Devonshire I found a spike 
with nine open flowers, and the pollinia in all were re- 
moved with one exception, and in this case a fly, too 
small to remove the pollinia, had become glued to the 
rostellum, and had there miserably perished. 

Dr. H. Miiller has published * some interesting 
observations on the difference in structure and manner 
of fertilisation, as well as on the intermediate forms 
between Epipactis ruhiginosa, 7iiiGrophyJla, and viridi- 
flora. The latter species is remarkable for the absence 
of a rostellum, and for being regularly self-fertilised. 
Self-fertilisation here follows from the incoherent 
pollen-grains in tlie lower part of the pollen-masses 

* • Veiliandl. d. Nat. Yer. f. W. stfal.' Ji.hig xxv. Ill Folge, v.Bd. 
pp. 7-3(5. 



Chap. IV. GOODYERA REPENS. 103 

emitting, whilst still within the anther-cells, their 
tubes, which penetrate the stigma ; and this occurs even 
in the bud. This species, however, is probably visited 
by insects, and occasionally crossed ; for the labellum 
contains nectar. E. microjphylla is intermediate in 
structure between E. latifoUa, which is always fertilised 
by the aid of insects, and E. viridiflora, which does not 
necessarily require any such aid. The whole of this 
memoir by Dr. H. Mtiller deserves to be attentively 
studied. 

Ejnpof/ium gmelini. — This plant, which has only 
once been found in Great Britain, has been fully de- 
scribed by Dr. Eohrbach in a special memoir. * The 
structure and manner of fertilisation is in many re- 
spects like that of Epipactis, to which genus the author 
believes the present one to be allied, though placed by 
Lindley amongst the Arethusese. Eohrbach saw the 
flowers visited by Bomhus lucorum, but it appears that 
only a few produce capsules. 

Goody era rejpens,^ — This genus is rather closely re- 
lated to Epipactis, in most of the characters with 
which we are concerned. The shield-like rostellum is 
almost square, and projects beyond the stigma ; it is 
supported on each side by sloping sides rising from 
the upper edge of the stigma, in nearly the same 
manner as we shall presently see in Sj)iranthes. The 
surface of the protuberant part of the rostellum is rough, 
and when dry can be seen to be formed of cells ; it is 
delicate, and, when slightly pricked, a little milky 
viscid fluid exudes; it is lined by a layer of ver} 
adhesive matter, which quickly sets hard when exposed 



• 'Ueber den Blutheiibau von f Specimens of this rare High- 

Epipogium,' &c. 186t); see also land Oicliid were kindly sent me 

Iriiiisfh, 'Beitrage zur liiologie by the Kev. G. Gordon uf Elgin. 
der Orehideen,' 1853, p. 5o. 



] 04: NEOTTE.E. Chap. IV. 

to the air. The protuberant surface of the rostelluin, 
when gently rubbed upwards, is easily removed, and 
carries with it a strip of membrane, to the hinder part 
of which the pollinia are attached. The sloping sides 
which support the rostellum are not removed at the 
same time, but remain projecting up like a fork and 
soon wither. The anther is borne on a broad elon- 
gated filament ; and a membrane on both sides unites 
this filament to the edges of the stigma, forming an 
imperfect cup or clinandrum. The anther-cells open 
in the bud, and the pollen-masses become attached 
by their anterior faces, just beneath their summits, 
to the back of the rostellum. Ultimately the anther 
opens widely, leaving the pollinia almost naked, but 
partially protected within the membranous cup or 
clinandrum. Each pollinium is partially divided 
lengthways ; the pollen-grains cohere in subtriangular 
packets, including a multitude of compound grains, each 
consisting of four grains ; and these packets are tied 
together by strong elastic threads, which at their upper 
ends run together and form a single flattened brown 
elastic ribbon, of which the truncated extremity adheres 
to the back of the rostellum. 

The surface of the orbicular stigma is remarkably 
viscid, which is necessary in order that the unusually 
strong threads connecting the packets of pollen should 
be ruptured. The labellum is partially divided into 
two portions ; the terminal portion is reflexed, and 
the basal portion is cup-formed and filled with nectar. 
The passage between the rostellum and labellum is 
contracted whilst the flower is young ; but when mature 
the column moves further back from the labellum, so 
as to allow of insects with the pollinia adhering to 
their proboscides, to enter the flowers more freely. In 
many of the specimens received, the pollinia had been 



Chap. IV. GOODYEEA REPENS. 105 

removed, and the fork-shaped supporting sides of the 
rostellum were partially withered. Mr. K. B. ThomsoQ 
inforDis me that in the north of Scotland he saw many 
humble-bees (Bomhus prat or urn) visiting the flowers 
with pollen-masses attached to their proboscides. 
This species grows also in the United States; and 
Professor Asa Gray* confirms my account of its 
structure and manner of fertilisation, which is likewise 
applicable to another and very distinct species, namely, 
Goodijera jpuhescens. 

Goodyera is an interesting connecting link between 
several very distinct forms. In no other member of 
the iN'eotteae observed by me is there so near an ap- 
proach to the formation of a true caudicle ; t and it is 
curious that in this genus alone the pollen-grains 
cohere in large packets, as in the Ophreoe. If the 
nascent caudicles had been attached to the lower ends 
of the pollinia, and they are attached a little beneath 
their summits, the poUinia would have been almost 
identical with those of a true Orchis. In the rostellum 
being supported by sloping sides, which wither when 
the viscid disc is removed, — in the existence of a 
membranous cup or clinandrum between the stigma 

* 'Amer. Journal of Science,* bundle of elastic threads, witli 

vol. xxxiv. 1862, p. 427. I for- very small and thin packets of 

merly thought that with this plant pollen-grains attached to them 

and Spiranthes, it was the label- and arranged like tiles one over 

lum which moved from the column the other. The two caudieles are 

to allow of the more free entrance united together near their basos, 

of insects ; but Professor Gray is where they are attached to a disc 

convinced that it is the column of membrane lined with viscid 

"which moves. matter. From the small size and 

t In a foreign species, (roof7?/<^ra extreme thinness of the b;isal 

discolor, sent me by Mr. Bateman, packets of pollen, and from tlie 

the pollinia approach in structure strength of their attachment to 

still more closely those of the the threads, I believe that they 

Ophreae ; for the pollinia extend are in a functionless condition ; 

into long caudicles, resembling in if so, these proloutjations of the 

form those of an Orchis. The pollinia are true caudicles. 
caudicle is here formed of a 



106 NEOTTE^. Chap. IV. 

and anther, — and in some other respects, we have a 
clear affinity with Spiranthes. In the anther having 
a broad filament w^e see a relation to Cephalanthera. 
In the structure of the rostellum, with the exception 
of the sloping sides, and in the shape of the labellum, 
Goodyera resembles Epipactis. Goodyera probably 
shows us the state of the organs in a group of Orchids, 
now mostly extinct, but the parents of many living 
descendants. 

Spiranthes aiitumnalis. — This Orchid with its pretty 
name of Ladies'-tresses, presents some interesting 
peculiarities.* The rostellum is a long, thin, flat pro- 
jection, joined by sloping shoulders to the summit of 
the stigma. In the middle of the rostellum a narrow 
vertical brown object (fig. 17, C) may be seen, bordered 
and covered by transparent membrane. This brown 
object I will call "the boat-formed disc." It forms 
the middle portion of the posterior surface of the 
rostellum, and consists of a narrow^ strip of the exterior 
membrane in a modified condition. When removed 
from its attachment, its summit (fig. E) is seen to be 
pointed, with the lower end rounded; it is slightly 
bowed, so as altogether to resemble a boat or canoe. 
It is rather more than -j-f.-^- of an inch in length, 
and less than -p-o-o '^^ breadth. It is nearly rigid, and 
appears fibrous, but is really formed of elongated 
and thickened cells, partially confluent. 

This boat, standing vertically up on its stern, is filled 
with thick, milky, extremely adhesive fluid, which, 
when exposed to the air, rapidly turns brown, and in 
about one minute sets quite hard. An object is well 
glued to the boat in four or five seconds, and when the 

* lamindebtefl toDr. Battersby me specimens. I subsequently 
of Torquay, and to Mr. A. G. examined many growing plants. 
More of Bembridtre, for sending 



Chap. IV. 



SPIRANTHES AUTUMNALIS. 



107 



cement is dry the attacliment is wonderfully strong. 
The transparent sides of the rostellum consist of mem- 
brane, attached behind to the edges of the boat, and 
folded over in front, so as to form the anterior face 
of the rostellum. This folded membrane, therefore, 
covers, almost like a deck, the cargo of viscid matter 
within the boat. 

Fig. 17. 




SpIRANTIIES AUTUMXALIS, OR LaDTES'-TrESSES. 



a. anther. 

p. pollen-masses. 

t. threads of the pollen-masses. 

cl. margin of clinandrura. 

r. rostellum. 

s. stigma. 

n. nectar receptacle. 

A. Side view of flower in its natural 
position, with the two lower 
sepals alone removed. The 
label lum can be recognised by- 
its fi'inged and reflexed lip. 

^. Side view enlarged of a mature 
flower, with all the sepals and 
petals removed. The positions 
of the labellum and of the 



upper sepal are shown by the 
dotted Hues. 

C. Front view of the stigma, and 

of the rostellum with its em- 
bedded, central, boat-formed 
disc. 

D. Front view of the stigma and of 

the rostellum after the disc has 
been removed. 

E. Disc, removed from the rostel- 

lum, greatly enlarged, viewed 
posteriorly, with the attached 
elastic threads of the pollen- 
masses ; the pollen-grains have 
been removed from the threads. 



The anterior face of the rostellum is slightly furrowed 
in a longitudinal line over the middle of the boat, and 



108 NEOTTE^. Chap. IV. 

is endowed with a remarkable kind of irritability ; 
for, if the furrow be touched very gently by a needle, 
or if a bristle be laid along the furrow, it instantly 
splits along its whole length, and a little milky 
adhesive fluid exudes. This action is not mechanical, 
or due to simple violence. The fissure runs up the 
whole length of the rostellum, from the stigma beneath 
to the summit : at the summit the fissure bifurcates, 
and runs down the back of the rostellum on each side 
and round the stern of the boat-formed disc. Hence 
after this splitting action the boat-formed disc lies 
quite free, but embedded in a fork in the rostellum. 
The act of splitting apparently never takes place 
spontaneously. I covered a plant with a net, and after 
five of the flowers had fully expanded they were kept 
protected for a week : I then examined their rostella, 
and not one had split; whereas almost every flower 
on the surrounding and uncovered spikes, which would 
almost certainly have been visited and touched by 
insects, had their rostella fissured, though they had 
been open for only twenty-four hours. Exposure for 
two minutes to the vapour of a little chloroform causes 
the rostellum to split ; and this we shall hereafter see 
is likewise the case with some other Orchids. 

When a bristle is laid for two or three seconds in the 
furrow of the rostellum, and the membrane has con- 
sequently become fissured, the viscid matter within 
the boat-formed disc, which lies close to the surface 
and indeed slightly exudes, is almost sure to glue the 
disc longitudinally to the bristle, and both are with- 
drawn together. When the disc, with the pollinia 
attached to it, is withdrawn, the two sides of the ros- 
tellum (fig. D), which have been described by some 
botanists as two distinct foliaceous projections, are left 
sticking up like a fork. This is the common con- 



Chap. IV. SPIEANTHES AUTUMNALIS. 109 

dition of the flowers after they have been open for a 
day or two, and have been visited by insects. The 
fork soon withers. 

Whilst the flower is in bud, the back of the boat- 
formed disc is covered with a layer- of large rounded 
cells, so that the disc does not strictly form the exterior 
surface of the back of the rostellum. These cells 
contain slightly viscid matter : they remain unaltered 
(as may be seen at fig. E) towards the upper end of 
the disc, but at the point where the pollinia are at- 
tached they disappear. Therefore I at one time con- 
cluded that the viscid matter contained in these cells, 
when they burst, serve to fasten the threads of the 
pollinia to the disc ; but, as in several other genera, 
in which a similar attachment has to be effected, I 
could see no trace of such cells, this view may be 
erroneous. 

The stigma lies beneath the rostellum, and projects 
with a sloping surface, as may be seen at B in the 
side-view: its lower margin is rounded and fringed 
with hairs. On each side a membrane (d, B) extends 
from the edges of the stigma to the filament of the 
anther, thus forming a membranous cup or clinandrum, 
in which the lower ends of the pollen-masses lie safely 
protected. 

Each pollinium consists of two leaves of pollen, 
quite disconnected at their lower and upper ends, but 
united for about half their length in the middle by 
elastic threads. A very slight modification would 
convert the two pollinia into four distinct masses, as 
occurs in the genus Malaxis and in many foreign 
Orchids. Each leaf consists of a double layer of 
pollen-grains, joined by fours together, and these 
united by elastic threads, which are more numerous 
along the edges of the leaves, and converge at the 



110 NEOTTE^. CuAP. IV. 

summit of the pollinhim. The leaves are very brittle, 
and, when placed on the adhesive stigma, large pieces 
are easily broken off. 

Long before the flower expands, the anther-cells, 
which are pressed against the back of the rostellum, 
open in their upper part, so that the included pollinia 
come into contact with the back of the boat-formed 
disc. The projecting threads then become firmly 
attached to rather above the middle part of the back 
of the disc. The anther-cells afterwards open lower 
down, and their membranous walls contract and be- 
come brown ; so that by the time the flower is fully 
expanded the upper part of the pollinia lie quite 
naked, with their bases resting in a little cup formed 
by the withered anther-cell, and laterally protected by 
the clinandrum. As the pollinia thus lie loose, they 
are easily removed. 

The tubular flowers are elegantly arranged in a 
spire round the spike, and project from it horizontally 
(fig. A). The labellum is channelled down the middle, 
and is furnished with a reflexed and fringed lip, on 
which bees alight ; its basal internal angles are pro- 
duced into two globular processes, which secrete an 
abundance of nectar. The nectar is collected (n, fig. 
B) in a small receptacle in the lov,^er part of the 
labellum. Owing to the protuberance of the inferior 
margin of the stigma and of the two lateral inflexed 
nectaries, the orifice into the nectar-receptacle is 
much contracted. When the flower first opens the 
receptacle contains nectar, and at this period the 
front of the rostellum, which is slightly furrowed, 
lies close to the channelled labellum ; consequently 
a passage is left, but so narrow that only a fine bristle 
can be passed down it. In a day or two the column 
moves a little farther from the labellum, and a wider 



Chap. IV. SPIRANTHES AUTUMNALIS. Ill 

passage is left for insects to deposit pollen on the 
stigmatic surface. On this slight movement of the 
column the fertilisation of the flower absolutely 
depends.* 

With most Orchids the flowers remain open for 
some time before they are visited by insects; but 
with Spiranthes I have generally found the boat- 
formed discs removed very soon after their expansion. 
For example, in the two last spikes which I happened 
to examine there were numerous buds on the summit 
of one, with only the seven lowest flowers expanded, 
of which six had their discs and pollinia removed; 
the other spike had eight expanded flowers, and the 
pollinia of all were removed. We have seen that when 
the flowers first open they would be attractive to 
insects, for the receptacle already contains nectar; 
and at this period the rostellum lies so close to the 
channelled labellum that a bee could not pass down 
its proboscis without touching the medial furrow of 
the rostellum. This I know to be the case by repeated 
trials with a bristle. 

We thus see how beautifully everything is contrived 
that the pollinia should be withdrawn by insects visit- 
in o- the flowers. They are already attached to the 
disc by their threads, and, from the early withering 
of the anther-cells, they hang loosely suspended but 
protected within the clinandrum. The touch of the 

♦ Profeasor Asa Gray was so of all the parts in Spirantlies with 

kind as to examine for me Spi- the exception that it is the column 

ranthes qradUs and cernua in the atid not the labellum, as I formrr- 

United States. He found the ly thought, which moves as the 

same general structure as in our flowers becomematu-e^ He adds 

8. autumnalis, and was struck that the widening oi the passage, 

with the narrowness of the passage which plays so important a part 

into the flower. He hns since in the fe.tihsation of the flower, 

confirmed ('Amer. Journ. of " is so striking t^iat we wundei 

Science/ vol. xxxiv. p. 427) my how we overlooked it. 
account of the structure and action 



1 12 NEOTTEiB. Chap. IV. 

proboscis causes the rostellum to sj)Iit in front and 
behind, and frees the long, narrow, boat-formed disc, 
wliich is filled with extremely viscid matter, and is sure 
to adhere longitudinally to the proboscis. When the 
bee flies away, so surely will it carry away the pollinia. 
As the pollinia are attached parallel to the disc, they 
adhere parallel to the proboscis. When the flower 
first opens and is best adapted for the removal of the 
pollinia, the labellum lies so close to the rostellum, 
that the pollinia attached to the proboscis of an insect 
cannot possibly be forced into the passage so as to 
reach the stigma ; they would be either upturned or 
broken off: but we have seen that after two or three 
days the column becomes more reflexed and moves 
from the labellum, — a wider passage being thus left. 
When I inserted the pollinia attached to a fine bristle 
into the nectar-recej)tacle of a flower in this condition 
(n, fig. B), it was pretty to see how surely the sheets 
of pollen were left adhering to the viscid stigma. It 
may be observed in the diagram, B, that owing to the 
projection of the stigma, the orifice into the nectar- 
receptacle (n) lies close to the lower side of the flower ; 
insects would therefore insert their proboscides along 
this lower side, and an open space above is thus left 
for the attached pollinia to be carried down to the 
stigma, without being brushed off. The stigma evi- 
dently projects so that the ends of the pollinia may 
strike against it. 

Hence, in Spiranthes, a recently expanded flower, 
which has its pollinia in the best state for removal, 
cannot be fertilised ; and mature flowers will be ferti- 
lised by pollen from younger flowers, borne, as we 
shall presently see, on a separate plant. In con- 
formity with this fact the stigmatic surfaces of the 
older flowers are far more viscid than those of the 



Chap. IV. SPIRANTHES AUTUMNALIS. 113 

younger flowers. Nevertheless, a flower which, in its 
early state had not been visited by insects would not 
necessarily, in its later and more expanded condition, 
have its pollen wasted : for insects, in inserting and 
withdrawing their proboscides, bow them forwards or 
upwards, and would thus often strike the furrow in the 
rostellum. I imitated this action with a bristle, and 
often succeeded in withdrawing the pollinia from old 
flowers. I was led to make this trial from having at 
first chosen old flowers for examination ; and on passing 
a bristle, or fine culm of grass, straight down into 
the nectary, the pollinia were never withdrawn ; but 
when it was bowed forward, I succeeded. Flowers 
which have not had their pollinia removed can be 
fertilised as easily as those which have lost them ; and 
I have seen not a few cases of flowers with their 
pollinia still in place, with sheets of pollen on their 
stigmas. 

At Torquay I watched for about half an hour a 
number of these flowers growing together, and saw 
three humble-bees of two kinds visit them. I caught 
one and examined its proboscis : on the superior 
lamina, some little way from the tip, two perfect 
pollinia were attached, and three other boat-formed 
discs without pollen ; so that this bee had removed 
the pollinia from five flowers, and had probably left 
the pollen of three on the stigmas of other flowers. 
The next day I watched the same flowers for a quarter 
of an hour, and caught another humble-bee at work ; 
one perfect pollinium and four boat-formed discs ad- 
hered to its proboscis, one on the top of the other, 
showing how exactly the same part of the rostellum 
had each time been touched. 

The bees always alighted at the bottom of the 
spike, and, crawling spirally up it, sucked one flower 



114 NEOTTE^. CHiP. IV. 

after ttie other. 1 believe humble-bees generally act 
in this manner when visiting a dense spike of flowers, 
as it is the most convenient method ; on the same 
principle that a woodpecker always climbs up a tree in 
search of insects. This seems an insignificant observa- 
tion ; but see the result. In the early morning, when 
the bee starts on her rounds, let us suppose that she 
alighted on the summit of a spike ; she would cer- 
tainly extract the poUinia from the uppermost and 
last opened flowers ; but when visiting the next suc- 
ceeding flower, of which the column in all probability 
would not as yet have moved from the labellum (for 
this is slowly and very gradually effected), the pollen- 
masses would be brushed off her proboscis and wasted. 
But nature suffers no such waste. The bee goes first 
to the lowest flower, and, crawling spirally up the 
spike, effects nothing on the first spike which she 
visits till she reaches the upper flowers, and then she 
withdraws the pollinia. She soon flies to another plant, 
and, alighting on the lowest and oldest flower, into 
which a wide passage will have been formed from the 
greater reflexion of the column, the pollinia strike the 
protuberant stigma. If the stigma of the lowest flower 
has already been fully fertilised, little or no pollen 
will be left on its dried surface ; but on the next 
succeeding flower, of which the stigma is adhesive, 
large sheets of pollen will be left. Then as soon as 
the bee arrives near the summit of the spike she will 
withdraw fresh pollinia, will fly to the lower flowers 
on another plant, and fertilise them ; and thus, as she 
goes her rounds and adds to her store of honey, she 
continually fertilises fresh flowers and perpetuates the 
race of our autumnal Spiranthes, which will yield 
honey to future generations of bees. 

Spiranthes australis. — This species, an inhabitant 



Chap. IV. LISTERA OVATA. 115 

of Australia, lias been described and figured by Mr. 
Fitzgerald.* The flowers are arranged on the spike 
in the same manner as in S. autumnalis ; and the 
labellum with two glands at its base closely resembles 
that of our species. It is therefore an extraordinary 
fact that Mr. Fitzgerald could not detect even in the 
bud any trace of a rostellum or of viscid matter. He 
states that the pollinia touch the upper edge of the 
stigma, and fertilise it at an early age. Protecting a 
plant from the access of insects by a bell-glass made 
no difference in its fertility ; and Mr. Fitzgerald, 
though he examined many flowers, never noticed the 
slightest derangement of the pollinia, or any pollen 
on the surfaces of the stigmas. Here then we have 
a species which fertilises itself as regularly as does 
Ophrijs apifera. It would, however, be desirable to 
ascertain whether insects ever visit the flowers, which 
it may be presumed secrete nectar, as glands are 
present ; and any such insects should be examined, so 
as to make certain that pollen does not adhere to some 
part of their bodies. 

Listera ovafa, or Tivay-Uade, — This Orchid is one 
of the most remarkable in the whole order. The 
structure and action of the rostellum has been the 
subject of a valuable paper in the * Philosophical 
Transactions,' by Dr. Hooker,t who has described 
minutely and of course correctly its curious structure ; 
he did not, however, attend to the part which insects 
play in the fertilisation of the flowers. C. K. Sprengel 
well knew the importance of insect-agency, but he 
misunderstood both the structure and the action of 
the rostellum. 

The rostellum is of large size, thin, or foliaceous, 

• 'Australian Orchids.' part ii. t * Philosophical Transactions,' 

1876. 1854, p. 259. 



116 



NEOTTE^. 



Chap. IV, 



convex in front and concave behind, with its sharp 
summit slightly hollowed out on each side ; it arches 
over the stigmatic surface (fig. 18, A, r, s). Internally, 

Fig, 18. 




LiSTERA OVATA, or Tvvay-blade. (Partly copied from Hooker.; 



col. 


summit of column. 


A. Flower viewed laterally, with 


a. 


dnther. 


all the sepals and petals, except 


V' 


pollen. 


the labellum, removed. 


r. 


rostellum. 


B. Ditto, with the pollinia re- 


s. 


stigma. 


moved, and with the rostellum 


/. 


labellum. 


bent down after the ejection 


n. 


nectar-secreting furrow. 


of the viscid matter. 



Chap. IV. 



LISTERA OVATA. 117 



it is divided by longitudinal septa into a series of 
loculi, which contain viscid matter and have the power 
of violently expelling it. These loculi show traces of 
their original cellular structure. I have met with this 
structure in no other genus except in the closely 
allied Neottia. The anther, situated behind the ros- 
tellum and protected by a broad expansion of the top 
of the column, opens in the bud. When the flower is 
fully expanded, the pollinia are left quite free, sup- 
ported behind by the anther-cells, and lying in front 
against the concave back of the rostellum, with their 
upper pointed ends resting on its crest. Each pol- 
linium is almost divided into two masses. The pollen- 
grains are attached together in the usual manner by 
a few elastic threads ; but the threads are weak, and 
large masses of pollen can be broken off easily. After 
the flower has long remained open, the pollen becomes 
more friable. The labellum is much elongated, con- 
tracted at its base, and bent downwards, as represented 
in the drawing ; the upper half above the bifurcation 
is furrowed along the middle ; and the borders of this 
furrow secrete much nectar. 

As soon as the flower opens, if the crest of the 
rostellum be touched ever so lightly, a large drop 
of viscid fluid is instantaneously expelled ; and this, 
as Dr. Hooker has shown, is formed by the coalescence 
of two drops proceeding from two depressed spaces on 
each side of the centre. A good proof of this fact 
was afforded by some specimens kept in weak spirits 
of wine, which apparently had expelled the viscid 
matter slowly, and here two separate little spherical 
balls of hardened matter had been formed, attached to 
the two pollinia. The fluid is at first slightly opaque 
and milky ; but on exposure to the air for less than 
a second, a film forms over it, and in two or three 



118 NE0TTE2E. Chap. IV. 

seconds the whole drop sets hard, soon assuming a 
purplish-brown tint. So exquisitely sensitive is the 
rostellum, that a touch from the thinnest human hair 
suffices to cause the explosion. It will take place 
under water. Exposure to the vapour of chloroform 
for about one minute also caused an explosion; but 
the vapour of sulphuric ether did not thus act, though 
one flower was exposed for five, and another for 
twenty minutes to a strong dose. The rostellum of 
these two flowers when afterwards touched exploded in 
the usual manner, so that sensitiveness had not been 
lost in either case. The viscid fluid when pressed 
between two plates of glass before it has set hard is 
seen to be structureless ; but it has a reticulated 
appearance, perhaps caused by the presence of glo- 
bules of a denser immersed in a thinner fluid. As the 
pointed tips of the poUinia lie on the crest of the 
rostellum, they are always caught by the exploded 
drop : I have never seen this once to fail. So rapid 
is the explosion and so viscid the fluid, that it is 
difficult to touch the rostellum with a needle, however 
quickly this may be done, without removing the 
poUinia. Hence, if a bunch of flowers be carried 
home in the hand, some of the sepals or petals will 
almost certainly touch the rostellum and withdraw the 
poUinia ; and this gives the false appearance of their 
having been ejected to a distance. 

After the anther-cells have opened and the naked 
poUinia have been left resting on the concave back of 
the rostellum, this latter organ curves a little forwards, 
and perhaps the anther also moves a little backwards. 
This movement is of much importance ; if it did not 
occur, the tip of the anther, within which the poUinia 
are lodged, would be caught by the exploded viscid 
matter, and the poUinia would be for ever locked up 



Chap. IV. LISTEEA OVATA. 



119 



and rendered useless. I once found an injured flower 
which had been pressed and had exploded before fully 
expanding, and the anther with the enclosed pollen- 
masses was permanently glued to the crest of the ros- 
tellum. The rostellum, which is naturally somewhat 
arched over the stigma, quickly bends forwards and 
downwards at the moment of the explosion, so as then 
to stand (fig. B) at right angles to the surface of the 
stigma. The pollinia, if not removed by the touching 
object which causes the explosion, become fixed to the 
rostellum, and by its movement are likewise drawn a 
little forward. If their lower ends are now freed by a 
needle from the anther-cells, they spring up ; but they 
are not by this movement placed on the stigma. In 
the course of some hours, or of a day, the rostellum 
not only slowly recovers its original slightly-arched 
position, but becomes quite straight and parallel to 
the stigmatic surface. This backward movement of 
the rostellum is of service ; for if after the explosion it 
had remained permanently projecting at right angles 
over the stigma, pollen could not readily have been 
deposited by insects on the viscid surface of the 
stigma. When the rostellum is touched so quickly 
that the pollinia are not removed, they are, as I have 
just said, drawn a little forward ; but by the subse- 
quent backward movement of the rostellum they are 
pushed back again into their original position. 

From the account now given we may safely infer 
how the fertilisation of this Orchid is effected. Small 
insects alight on the labellum for the sake of the 
nectar copiously secreted by it ; as they lick this they 
slowly crawl up its narrowed surface until their heads 
stand directly beneath the overarching crest of the 
rostellum ; when they raise their heads they touch the 
crest ; this then explodes, and the pollinia are instantly 



120 NEOTTE^. Chap. IV 

and firmly cemented to tlieir heads. As soon as tlie 
insect flies away, it withdraws the poUinia, carries 
them to another flower, and there leaves masses of the 
friable pollen on the adhesive stigma. 

In order to witness what I felt sure would take 
place, I watched for an hour a group of plants on 
three occasions; each time I saw numerous speci- 
mens of two small Hymenopterous insects, namely, a 
Haemiteles and a Cryptus, flying about the plants and 
licking up the nectar ; most of the flowers, which were 
visited over and over again, already had their pollinia 
removed, but at last I saw both these species crawl 
into younger flowers, and suddenly retreat with a pair 
of bright yellow pollinia sticking to their foreheads ; I 
caught them, and found the point of attachment was to 
the inner edge of the eye; on the other eye of* one 
specimen there was a ball of the hardened viscid 
matter, showing that it had previously removed 
another pair of pollinia, and in all probability had subse- 
quently left them on the stigma of a flower. As these 
insects were captured, I did not witness the act of fertili- 
sation ; but Sprengel saw a Hymenopterous insect 
leave its pollen-mass on the stigma. My son watched 
another bed of this Orchid at some miles' distance, and 
brought me home the same Hymenopterous insects 
with attached pollinia, and he saw Diptera also 
visiting the flowers. He was struck with the number 
of spider-webs spread over these plants, as if the 
spiders were aware how attractive the Listera was to 
insects. 

To show how delicate a touch suffices to cause 
the rostellum to explode, I may mention that I found 
an extremely minute Hymenopterous insect vainly 
struggling to escape, with its head cemented by the 
hardened viscid matter, to the crest of the rostellum 



Chap. IV. LISTEEA OVATA. 121 

and to the tips of the pollinia. The insect was not 
so large as one of the pollinia, and after causing the 
explosion had not strength enough to remove them ; 
it was thus punished for attempting a work beyond 
its strength, and perished miserably. 

In Spiranthes the young flowers, which have their 
pollinia in the best state for removal, cannot possibly 
be fertilised ; they must remain in a virgin condition 
until they are a little older and the column has 
moved away from the labellum. Here the same end 
is gained by widely different means. The stigmas of 
the older flowers are more adhesive than those of the 
younger flowers. These latter have their pollinia 
ready for removal ; but immediately after the rostellum 
has exploded, it curls forwards and downwards, thus 
protecting the stigma for a time; but it slowly be- 
comes straight again, and now the mature stigma is 
left freely exposed, ready to be fertilised. 

I wished to know whether the rostellum would 
explode, if never touched ; but I have found it difficult 
to ascertain this point, as the flowers are highly at- 
tractive to insects, and it is scarcely possible to exclude 
very minute ones, the touch of which suffices to cause 
the explosion. Several plants were covered by a net 
and left till the surrounding plants had set their 
capsules ; and the rostella in most of the covered-up 
flowers were found not to have exploded, though their 
stigmas were withered, and the pollen mouldy and 
incapable of removal. Some few of the very old 
flowers, however, when roughly touched, were still 
capable of a feeble explosion. Other flowers under 
the nets had exploded, and they had the tips of their 
pollinia fixed to the crest of the rostellum ; but whether 
these had been touched by some minute insect, or had 
exploded spontaneously, it was impossible to deter- 



122 NEOTTE^. Chap. IV 

mine. It should be observed, that although I looked 
carefully, not a grain of pollen could be found on the 
stigmas of any of these flowers, and their ovaria had 
not swollen. During a subsequent year, several plants 
were again covered by a net, and I found that the 
rostellum lost its power of explosion in about four 
days ; the viscid matter having turned brown within 
the loculi of the rostellum. The weather at the time 
was unusually hot, and this probably hastened the 
process. After the four days the pollen had become 
very incoherent, and some had fallen on the tv/o 
corners, and even over the whole surface of the stigma, 
which was penetrated by the pollen-tubes. But the 
scattering of the pollen was largely aided by, and 
perhaps wholly depended on, the presence of Thrips 
— insects so minute that they could not be excluded 
by any net, and which abounded on the flowers. This 
plant, therefore, is capable of occasional self-fertilisa- 
tion, if the access of winged insects be prevented ; but 
I have every reason to believe that this occurs very 
rarely in a state of nature. 

That insects do their work of cross-fertilisation 
efi'ectually is shown by the following cases. The 
seven upper flowers on a young spike with many 
unexpanded buds, still retained their pollinia, but 
these had been removed from the ten lower flowers ; 
and there was pollen on the stigmas of six of them. 
In two spikes taken together, the twenty-seven lower 
flowers all had their pollinia removed, and had pollen 
on their stigmas; these were succeeded by five open 
flowers with the pollinia not removed and without any 
pollen on the stigmas ; and these were succeeded by 
eighteen buds. Lastly, in an older spike with forty- 
four fully expanded flowers, the pollinia had been 
removed from everv single one ; and tliere was pollen. 



Chap. IV. LISTER A OVATA. 123 

generally in large quantity, on all the stigmas which 
I examined. 

I will recapitulate the several special adaptations 
for the fertilisation of this plant. The anther-cells 
open early, leaving the pollen-masses free, protected 
by the summit of the column, and with their tips 
resting on the concave crest of the rostellum. The 
rostellum then slowly curves over the stigmatic 
surface, so that its explosive crest stands at a little 
distance from the summit of the anther; and this 
is very necessary, otherwise the summit would be 
caught by the viscid matter, and the pollen for ever 
locked up. The curvature of the rostellum over the 
stigma and over the base of the labellum is excellently 
adapted to favour an insect striking the crest when it 
raises its head, after having crawled up the labellum 
and licked the last drop of nectar. The labellum, as 
C. K. Sprengel has remarked, becomes narrower where 
it joins the column beneath the rostellum, so that 
there is no risk of an insect going too much to either 
side. The crest of the rostellum is so exquisitely 
sensitive, that a touch from a very minute insect 
causes it to rupture at two points, and instantly two 
drops of viscid Huid are expelled, which coalesce. This 
viscid fluid sets hard in so wonderfully rapid a manner 
that it rarely fails to cement the tips of the pollinia, 
nicely laid on the crest of the rostellum, to the fore- 
head of the touching insect. As soon as the rostellum 
has exploded it suddenly curves downwards so as to 
project at right angles over the stigma, protecting it 
from impregnation at an early age, in the same manner 
as the stigmas of the young flowers of Spiranthes are 
protected by the labellum clasping the column. But 
as the column of Spiranthes after a time moves from 
the labellum, leaving a free passage for the introduc* 



124 NEOTTE^. Chap. IV. 

tion of the pollinia, so here the rostellum moves back- 
wards, and not only recovers its former arched position, 
but stands upright, leaving the stigmatic surface, now 
rendered more adhesive, perfectly free for pollen to be 
left on it. The pollen-masses, when once cemented to 
an insect's forehead, will remain attached to it, until 
they are brought into contact with the stigma of a 
mature flower ; and then these encumbrances will be 
removed, by the rupturing of the weak elastic threads 
which tie the grains together ; the flower being at tlie 
same time fertilised. 

Listera cordata. — Professor Dickie of Aberdeen was 
so kind as to send me, but rather too late in the 
season, two sets of specimens. The flowers have essen- 
tially the same structure as in the last species. The 
loculi of the rostellum are very distinct. Two or three 
little hairy points project from the middle of the crest 
of the rostellum ; but I do not know whether these 
have any functional importance. The labellum has 
two basal lobes (of which vestiges may be seen in 
L. ovata) which curve up on each side ; and these 
would compel an insect to approach the rostellum 
straight in front. In two of the flowers the pollinia 
were firmly cemented to the crest of the rostellum ; 
but in almost all the others the pollinia had been 
previously removed by insects. 

In the following year Professor Dickie observed the 
flowers on living plants, and he informs me that, when 
the pollen is mature, the crest of the rostellum is 
directed towards the labellum, and that, as soon as 
touched, the viscid matter explodes, the pollinia becom- 
ing attached to the touching object ; after the explosion, 
the rostellum bends downwards, thus protecting the 
virgin stigmatic surface ; subsequently it rises up and 
exposes the stigma ; sc that here everything goes on 



Chap. IV. NEOTTIA NIDUS- A VIS. 125 

as 1 have described under Listera ovata. The flowers 
are frequented by minute Diptera and Hymenoptera. 

Neottia nidus-avis. — I made numerous observations 
on this plant, the Bird's-nest Orchis,* but they are not 
worth giving, as the action and structure of every 
part is almost identically the same as in Listera ovata 
and eordata. On the crest of the rostellum there are 
about six minute rough points, which seem particularly 
sensitive to a touch, causing the expulsion of the 
viscid matter. The exposure of the rostellum to the 
vapour of sulphuric ether for twenty minutes did not 
prevent this action, when it was touched. The label- 
lum secretes plenty of nectar, which I mention merely 
as a caution, because during one cold and wet season 
I looked several times and could not see a drop, and 
was perplexed at the apparent absence of any attrac- 
tion for insects ; nevertheless, had I looked more per- 
severingly, perhaps I should have found some. 

The flowers must be freely visited by insects, for 
all in one large spike had their pollinia removed. 
Another unusually fine spike, sent me by Mi. Oxenden 
from South Kent, had borne forty-one flowers, and it 
produced twenty-seven large seed-capsules, besides 
some smaller ones. Dr. H. Miiller of Lippstadt in- 
forms me that he has seen Diptera sucking the nectar 
and removing the pollinia. 

The pollen-masses resemble those of Listera, in 
consisting of compound grains tied together by a few 
weak threads ; they differ in being much more inco- 
herent ; after a few days they swell and overhang the 
sides and summit of the rostellum ; so that if the ros- 
tellum of a rather old flower be touched and an explo- 



* This unnatural sickly- looking lives ; but, acoording to Irmisch 

plant Las generally been "supposed (' Beitrage zur Biologic und Mor- 

to b' parasitic on rhe roots of tlie pliologie der Orchideen,' 1853, s. 

trees under the shade of which it 25), this certainly is not the case. 



126 NEOTTE^. Chap. IV. 

sion caused, the pollen-masses are not so neatly caught 
by their tips as those of Listera. Thus a good deal of 
the friable pollen is often left behind in the anther- 
cells and is apparently wasted. Several plants were 
protected from the access of winged insects by a net, 
and after four days the rostella had almost lost their 
sensitiveness and power to explode. The pollen had 
become extremely incoherent, and in all the flowers 
much had fallen on the stigmas which were penetrated 
by the pollen-tubes. The spreading of the pollen 
seems to be in part caused by the presence of Thrips, 
many of which minute insects were crawling about the 
flowers, dusted all over with pollen. The covered-up 
plants produced plenty of capsules, but many of these 
were much smaller and contained fewer seeds than 
those produced by the adjoining uncovered plants. 

If insects had been forced by the labellum being 
more upturned to brush against the anther and stigma, 
they would always have been smeared with the pollen 
as soon as it became friable ; and they would thus 
have fertilised the flowers effectually without the aid 
of the explosive rostellum. This conclusion interested 
me, because, when previously examining Cephalan- 
thera, with its aborted rostellum, its upturned label- 
lum and friable pollen, I had speculated how a transi- 
tion, with each gradation useful to the plant, could 
have been effected from the state of the pollen in the 
similarly constructed flowers of Epipactis, with their 
pollinia attached to a well-developed rostellum, to the 
present condition of Cephalanthera. Neottia nidus- 
avis shows us how such a transition might have been 
efi'ected. This Orchid is at present mainly fertilised 
by means of the explosive rostellum, which acts effec- 
tually only as long as the pollen remains in mass ; 
but we have seen that as the flower grows old the 
pollen swells aud becomes friable, and is then apt to 



Chap. IV. THELYMITRA. 127 

fall or be transported by rainute crawling insects on 
to the stigma. By this means self-fertilisation is 
assured, should larger insects fail to visit the flowers. 
Moreover, the pollen in this state readily adheres to 
any object; so that by a slight change in the shape of 
the flower, which is already less open or more tubular 
than that of Listera, and by the pollen becoming 
friable at a still earlier age, its fertilisation would be 
rendered more and more easy without the aid of the 
explosive rostellum. Ultimately it would become a 
superfluity ; and then, on the principle that every part 
which is not brought into action tends to disappear, 
from causes which I have elsewhere endeavoured to 
explain,* this would happen with the rostellum. We 
should then see a new species, in the condition of 
Cephalanthera as far as its means of fertilisation were 
concerned, but in general structure closely allied to 
Neottia and Listera. 

Mr. Fitzgerald, in the introduction to his * Austra- 
lian Orchids,' says that Thelymitra carnea, one of 
the Neottea3, invariably fertilises itself by means of the 
incoherent pollen falling on the stigma. Nevertheless 
a viscid rostellum, and other structures adapted for 
cross-fertilisation are present. The flowers seldom 
expand, and never until they have fertilised them- 
selves ; so that they seem tending towards a cleisto- 
gene condition. Thelymitra longifolia is likewise fer- 
tilised in the bud, according to Mr. Fitzgerald, but 
the flowers open for about an hour on fine days, and 
thus cross-fertilisation is at least possible. On the 
other hand, the species of the allied genus Diuris are 
said to be wholly dependent on insects for their 
fertilisation. 

♦ ' Variation of Animals and Plants under Domestication,' 2nd edit 
voL ii. p. 309. 



128 MALAXED. Chap. V 



CHAPTER V. 

MALAXED AND EPIDENDRE^. 

Malaxis paludosa— Masdevallia, curious closed flowers — Bolbophyllmn, 
labellum kept in constant movement by every breath of air — Dendro- 
bium, contrivance for self-fertilisation — Cattleya, simple manner of 
fertilisation — Epidendrum — Self-fertile Epidendrese. 

1 HAVE now described the manner of fertilisation of 
fifteen genera, found in Britain, which belong, accord- 
ing to Lindley's classification, to the Ophrese, Arethu- 
seae, and Neottese. A brief account of several foreign 
genera belonging to these same tribes has been added, 
from observations published since the appearance of 
the first edition of this book. We will now turn to 
the great exotic tribes of the Malaxe?e, Epidendrese, 
and Vandese, which ornament in so wonderful a 
manner the tropical forests. My chief object in 
examining these latter forms has been to ascertain 
whether their flowers were as a general rule fertilised 
by pollen brought by insects from another plant. J 
also wished to learn whether the pollinia underwent 
tliose curious movements of depression by which, as 
I had discovered, they are placed, after being removed 
by insects, in the proper position for striking the 
stigmatic surface. 

By the kindness of many friends and strangers T 
have been enabled to examine fresh flowers of several 
species, belonging to at least fifty exotic genera, in 
the several sub-tribes of the above three great tribes.* 

* I am particularly indebted to Dr. Hooker, who on every orca- 



Chap. V 



MALAXIS PALUDOSA. 



129 



It is not my intention to describe the means of fertili- 
sation in all these genera, but merely to select a few 
curious cases which illustrate the foregoing descrip- 
tions. The diversity of the contrivances adapted to 
favour the intercrossing of flowers, seems to be ex- 
haustless. 



MALAXED. 

Malaxis paludosa. — This rare orchid * is the sole 
representative of the tribe in this country, and it is 
the smallest of all the British species. The labellum 
is turned upwards,! instead of downwards, so that it 
does not afford a landing-place for insects as in most 
other Orchids. Its lower margin clasps the column, 
making the entrance into the flower tubular. From 



sion has given me liis invaluable 
advice, and has never become 
weary of sending me specimens 
from the Koyal Gardens at Kew. 

Mr. James Veitch, jun., has 
generously given me many biau- 
tiful Orchids, some of which were 
of especial service. Mr. R. Parker 
also sent me an extremely valu- 
able series of forms. Lady Dorothy 
Nevill most kindly placed her 
magnificent collection of Orchids 
at my disposal. Mr. Eucker of 
West Hill, Wandsworth, sent me 
repeatedly lar^e spikes of Catase- 
tum. a Mormodes of extreme value 
and some Dtndrobiums. Mr. 
Ri;dgers of Sevenoaks has given 
me interesting inforruation. Mr. 
Bateman, so well known for his 
magnificent work on Orchids, 
sent me a number of interesting 
forms, including the wcmderful 
Angripcum sesquipedale. I am 
greatly indebted to jMr. Turnbull 
of Down for allowing me the free 
use of his hothouses, and for 
giving me some interesting Or- 
chida ; and to his gardener, Mr. 

7 



Ilorwood, for his aid in some of 
my observations. 

Professor Oliver has kindly 
assisted me with his large stores 
of knowledge, and has called my 
attention to several papers. Lastly, 
Dr. Lindley has sent me fresh 
and dried specimens, and has in 
the kindest manner helped me in 
various ways. 

To these gentlemen I can only 
express my corlial thanks for 
their unweai'ied and generous 
kindness. 

* I am greatly indebted to Mr. 
Wallis, of Hartfield, in Sussex, 
for numerous living specimens of 
this Orchid. 

t Sir James Smith. I believe, 
first noticed this fact in the 
' English Flora,' vol. iv. p. 47, 
1828. Towards the summit of 
the spike the lower sepal does not 
depend, as represented in the 
woodcut (fig. 19, A), but projects 
nearly at right angles. Nor are 
the flowers always so completely 
twisted round aa licre represented 



lig. 19, 




^--Aii^jJU^ 



MaLAXIS PALUDOfiA. 

(Partly copied from Bauer, but modified from living specimens.) 



a. anther. v. spiral vessels. 

p. pollen. r. rostellum. 

cl. clinandrum. s. stigma. 
I. label lum. 

tt. the sepal which in most orchids 
stands on the upper side of the 
flower. 

k. Perfect flower viewed laterally, 
with the labellum in its natu- 
ral position, upwards. 

R, Column viewed in front, showing 
the rostellum, the pocket-like 
stigma, and the anterior late- 
ral portions of tne clinandrum. 



C. Back view of the column in a 

flower-bud, showing the anther 
with the included pear-shaped 
polliuia dimly seen, and the 
posterior edges of the clinan- 
drum. 

D. Back view of an expanded flower, 

with the anther now contracted 
and shrivelled, exposing the 
pollinia. 

E. The two pollinia ati»ched to a 

little transverse mass of viscid 
matter, hardened by spirits of 
wine. 



Chap. V. MALAXIS PALUDOSA. 131 

its position it partially protects the organs of fructi- 
fication (fig. 19). In most of the Orcliidese, the upper 
sepal and the two upper petals afford protection ; but 
here these two petals and all the sepals are reflexed 
(as may be seen in the drawing, fig. A), apparently to 
allow insects freely to visit the flower. The position 
of the labellum is the more remarkable, because it 
has been purposely acquired, as shown by the ovarium 
being spirally twisted. In all Orchids the labellum 
is properly directed upwards, but assumes its usual 
position on the lower side of the flower by the twist- 
ing of the ovarium ; but in Malaxis the twisting has 
been carried so far that the flower occupies the posi- 
tion which it would have held if the ovarium had 
not been at all twisted, and which the ripe ova- 
rium afterwards assumes, by a process of gradual 
untwisting. 

When the minute flower is dissected, the column is 
seen to be longitudinally tripartite; the middle 
portion of the upper half (see fig. B) is the rostellum. 
The upper edge of the lower part of the column 
projects where united to the base of the rostellum, 
and forms a rather deep fold. This fold is the stig- 
matic cavity, and may be compared to a waistcoat- 
pocket. I found pollen-masses which had their broad 
ends pushed by insects into this pocket ; and a 
bundle of pollen-tubes had here penetrated the 
stigmatic tissue. 

The rostellum, which stands immediately above the 
stigmatic cavity, is a tallrmembranous projection of a 
whitish colour, formed of square cells, and is covered 
with a thin layer of viscid matter : it is slightly con- 
cave posteriorly, and its crest is surmounted by a 
minute tongue-shaped mass of viscid matter. The 
column, with its narrow pocket-like stigma and the 



132 MALAXED. Chap. V. 

rostellum above, is united on each side behind to a 
'green membranous expansion, convex exteriorly and 
concave interiorly, of which the summits on each side 
are pointed and stand a little above the crest of the 
rostellum. These two membranes sweep round (see 
back views, figs. C and D), and are united to the 
filament or base of the anther ;. they thus form a cup- 
like clinandrum behind the rostellum. The use of this 
cup is to protect laterally the pollen-masses. When 
I have to treat of the homologies of the different parts, 
it will be shown by the course of the spiral vessels 
that these two membranes consist of the two upper 
anthers of the inner whorl, in a rudimentary condition, 
but utilised for this special purpose. 

In a flower before it expands, a little mass or drop 
of viscid fluid may be seen on the crest of the ros- 
tellum, rather overhanging its front surface. After 
the flower has remained open for a little time, this 
drop shrinks and becomes more viscid. Its chemical 
nature is difi'erent from that of the viscid matter in 
most Orchids, for it remains fluid for many days, 
though fully exposed to the air. From these facts 
I concluded that the viscid fluid exuded from ^ the 
crest of the rostellum; but fortunately I examined 
a closely-allied Indian form, namely, the Microstijlia 
rhedii (sent me from Kew by Dr. Hooker), and in 
this, before the flower opened, there was a similar drop 
of viscid matter ; but on opening a still younger bud, 
I found a minute, regular, tongue-shaped projection 
on the crest of the rostellum, formed of cells, which 
when slightly disturbed resolved themselves into a 
drop of viscid matter. At this age, also, the front 
surface of the whole rostellum, between its crest and 
the pocket-like stigma, was coated with cells filled 
with similar brown viscid matter ; so that there can 



Chap. V. MALAXIS PALUDOSA. 133 

be little doubt, had I examined a young enough bud 
of Malaxis, I should have found a similar minute 
tongue-shaped cellular projection on the crest of the 
rostellum. 

The anther opens widely whilst the flower is in 
bud, and then shrivels and contracts downwards, so 
that, when the flower is fully expanded, the pollinia 
are quite naked, with the exception of their broad 
lower ends, w^hich rest in two little cups formed by 
the shrivelled anther-cells. This contraction of the 
anther is represented in fig. D in comparison with fig. 
C, which shows the state of the anther in a bud. 
The upper and much pointed ends of the pollinia 
rest on, but project beyond, the crest of the rostellum; 
in the bud they are unattached, but by the time the 
flower opens they are always caught by the posterior 
surface of the drop of viscid matter, of which the 
anterior surface projects slightly beyond the face of 
the rostellum. That they are caught without any 
mechanical aid I ascertained by allowing some buds 
to open in my room. In fig. E the pollinia are shown 
exactly as they appeared (but not quite in their 
natural position) when removed by a needle from a 
specimen kept in spirits of wine, in which the irre- 
gular little mass of viscid matter had become hardened 
and adhered firmly to their tips. 

The pollinia consist of two pairs of very thin leaves 
of waxy pollen ; and the four leaves are formed of 
angular compound grains which never separate. As 
the pollinia are almost loose, being retained merely by 
the adhesion of their tips to the viscid fluid, and by 
their bases resting in the shrivelled anther-cells, and 
as the petals and sepals are much reflexed, the pollinia, 
when the flower is fully expanded, would have been 
liable to be blown away or out of their proper position, 



134 MALAXE.E. CiiAP. V, 

had it not been for the membranous expansions on 
each side of the column forming the clinandrum, 
within which they lie safely. 

When an insect inserts its proboscis or head into 
the narrow space between the upright labellum and 
the rostellum, it will infallibly touch the little pro- 
jecting viscid mass, and as soon as it flies away it 
will withdraw the pollinia. I easily imitated this 
action by inserting any small object into the tubular 
flower between the labellam and rostellum. When 
the insect visits another flower, the very thin pollen- 
leaves attached parallel to the proboscis, or head, will 
be forced into the pocket-like stigma with their broad 
ends foremost. I found pollinia in this position glued 
to the upper membranous expansion of the rostellum, 
and with a large number of pollen-tubes penetrating 
the stigmatic tissue. The use of the thin layer of 
viscid matter, which coats the surface of the rostellum 
in this genus and in Microstylis, and which is of no 
use for the transportal of the pollen from flower to 
flower, seems to be to keep the leaves of pollen fixed 
in the narrow stigmatic cavity when their lower ends 
have been inserted by insects. This fact is rather 
interesting under a homological point of view, for, as 
we shall hereafter see, the primordial nature of the 
viscid matter of the rostellum is that which is common 
to the stigmatic secretion of most flowers, namely, the 
retention of the pollen, when placed by any means on 
its stigma. 

The flowers of the Malaxis, though so small and 
inconspicuous, are highly attractive to insects. This 
was shown by the pollinia having been removed from 
all the flowers on the spikes which I examined, 
excepting from one- or two close under the buds. In 
some old flower-spikes every single pollinium had 



Chap.y. pleueothallis peolifera. 135 

been carried away. Insects sometimes remove only 
one of the two pairs. I noticed a flower with all four 
pollen-leaves still in place, with a single one in the 
stigmatic cavity; and this mnst clearly have been 
brought by some insect. Within the stigmas of many 
other flowers pollen-leaves were observed. The plant 
produces plenty of seed ; and thirteen of the twenty-one 
lower flowers on one spike had formed large capsules. 

We will now turn to some exotic genera. The pol- 
linia of Fleurothallis proUfera and ligidata (?) have a 
minute caudicle, and mechanical aid is requisite to 
force the viscid matter from the under side of the 
rostellum into the anther, thus to catch the caudicles 
and remove the pollinia. On the other hand, in our 
British Malaxis and in Microstijlis rhedii from India, 
the upper surface of the minute tongue-shaped ros- 
tellum becomes viscid and adheres to the pollinia 
without any mechanical aid. This appears likewise to 
be the case with Stelis racemiflora, but the flowers were 
not in a good state for examination. I mention this 
latter flower partly because some insect in the hot- 
house at Kew had removed most of the pollinia, and 
had left some of them adhering to the lateral stigmas. 
These curious little flowers are widely expanded and 
much exposed ; but after a time the three sepals close 
together with perfect exactness, so that it is scarcely 
possible to distinguish an old flower from a bud : yet, 
to my surprise, the closed flowers opened when im- 
mersed in water. 

The allied Masdevallia fenestrata bears an extra- 
ordinary flower. The three sepals instead of closing, 
as in the case of Stelis after the flower has remained 
for a time expanded, cohere togetlier and never open. 
Two minute, lateral, oval windows (hence the name 
fenestrata), are seated high up the flower opposite each 



136 MALAXE.E. Chap. V. 

other, and afford the only entrance ; but the presence 
of these two minute windows (fig. 20) shows how neces- 
sary it is that insects should visit the flower in this 
case as in that of most other Orchids. How insects 
perform the act of fertilisation I have failed to under- 
stand. At the bottom of the roomy and dark chamber 
formed by the closed sepals, the minute column stands, 
and in front of it is the furrowed labellum, with a 
highly flexible hinge, and on each side the two upper 
petals ; a little tube being thus formed. When there- 
p. 20 ^^^'® ^ minute insect enters, or 

^^.^^^^ which is less probable, a larger in- 
/^'^ '> ^^'f^^ sect inserts its proboscis through 
'''< ^ 'tj either window, it has to find by 
the sense of touch the inner tube 
i/ in order to reach the nectary at 

y the base of the flower. Within 

^^^/A — ^ the little tube, formed by the 

Masdevallia fenes- column, labellum, and lateral 
TRATA. petals, a broad and hinged rostel- 

The window on the near side inm proi'ects at rifi^ht auHes, 

IS shown darkly shaded. i • i -n i , t 

which can easily be upturned. 

Its under surface is viscid, and 
this viscid matter soon sets hard and dry. The minute 
caudicles of the pollinia, projecting out of the anther- 
case, rest on the base of the upper membranous surface 
of the rostellum. The stigmatic cavity when mature 
is not very deep. After cutting away the sepals I 
vainly endeavoured, by pushing a bristle into the 
tubular flower, to remove the pollinia, but by the aid 
of a bent needle, this was effected without much 
difficulty. The whole structure of the flower seems 
as if intended to prevent the flower from being easily 
fertilised ; and this proves that we do not understand 
its structure. Some small insect had entered one of 



Chap. V. BOLBOPHYLLUM. 137 

the flowers in the hothouse at Kew, for many eggs 
were deposited within it, near the base. 

Of Bolbophyllum I examined the curious little 
flowers of four species, which I will not attempt fully 
to describe. In B. cupreum and coeoinum, the upper and 
lower surfaces of the rostellum resolve themselves into 
viscid matter, which has to be forced upwards by insects 
into the anther, so as to secure the pollinia. I effected 
this easily by passing a needle down the flower, which 
is rendered tubular by the position of the labellum, 
and then withdrawing it. In B. rliizophorse the anther- 
case moves backwards, when the flower is mature, 
leaving the two pollen-masses fully exposed, adhering 
to the upper surface of the rostellum. They are held 
together by viscid matter, and, judging from the 
action of a bristle, are always removed together. The 
stigmatic chamber is very deep with an oval orifice, 
which exactly fits one of the two pollen-masses. After 
the flower has remained open for some time, the sides 
of the oval orifice close in and shut the stigmatic 
chamber completely, — a fact which I have observed in 
no other Orchid, and which, I presume, is here related 
to the much exposed condition of the whole flower. 
When the two pollinia were attached to a needle or 
bristle, and were forced against the stigmatic chamber, 
one of the two glided into the small orifice more readily 
than could have been anticipated. Nevertheless, it is 
evident that insects must place themselves on suc- 
cessive visits to the flowers in precisely the same 
position, so as first to remove the two pollinia, and 
then force one of them into the stigmatic orifice. The 
two upper filiform petals would serve as guides to 
the insect ; but the labellum, instead of making the 
flower tubular, hangs down just like a tongue out of a 
widely open mouth. 



138 MALAXED. Chap. V 

The labelliim in all the species which I have seen, 
more especially in B. rhizopliorse, is remarkable by 
being joined to the base of the column by a very 
narrow, thin, white strap, which is highly elastic and 
flexible ; it is even highly elastic when stretched, 
like an india-rubber band. When the flowers of this 
species were blown by a breath of wind the tongue-like 
labella all oscillated to and fro in a very odd manner. 
In some species not seen by me, as in B, harbigerum, 
the labellum is furnished with a beard of fine hairs, 
and these are said to cause the labellum to be in 
almost constant motion from the slightest breath of 
air. What the use can be of this extreme flexibility 
and liability to movement in the labellum, I cannot 
conjecture, unless it be to attract the notice of insects, 
as the flowers of these species are dull-coloured, small, 
and inconspicuous, instead of being large, brightly- 
coloured, and conspicuous or odoriferous, as in so many 
other Orchids. The labella of some of the species are 
said to be irritable, but I could not detect a trace of 
this quality in those examined by me. According to 
Lindley, the labellum of the allied Megadinium falca- 
tum spontaneously oscillates up and down. 

The last genus of the Malaxea6 which I will mention 
is Dendrobium, of which one at least of the species, 
namely D. chrysanthum, is interesting, from being 
apparently contrived to effect its own fertilisation, if 
an insect, when visiting the flower, should fail to 
remove the pollen-masses. The rostellum has an 
upper and a small lower surface composed of mem- 
brane; and between these is a thick mass of milky- 
white matter which can be easily forced out. This 
white matter is less viscid than is usual ; but when 
exposed to the air a film forms over it in less than 
half a minute, and it soon sets into a waxy or cheesy 



Chap. V. 



DENDKOBIUM CHKYSANTHUM. 



139 



substance. The large concave but shallow stigmatic 
surface is seated beneath the rostellum. The pro- 
duced anterior lip of the anther (see A) almost entirely 
covers the upper surface of the rostellum. The fila- 

Fig. 21. 




DlOTDROBIDM CIIRYSANTHUM. 



anther. s. stigma. 

rostellum. /. labellum. 
n. nectary. 

Lateral view of flower, with the 
anther in its proper position, 
before the, ejection of the pol- 
linia. All the sepals and petals 
are removed except the label- 
lum, which is longitudinally 
bisected. 



B. Outline of column, viewed later- 

ally, after the anther has ejected 
the pollinia. 

C. Front view of column, showing 

the empty cells of the anther, 
after it has ejected its pollinia. 
The anther is represented hang- 
ing too low down, and covering 
more of the stigma than it 
really does. 



ment of the anther is of considerable length, but is 
hidden in the side view, A, behind the middle of the 
anther; in the section, B, it is seen, after it has 
sprung forward : it is elastic, and presses the anther 
firmly down on the inclined surface of the clinan- 



140 MALAXED Chap. V 

drum (see fig. B) which lies behind the rostellum. 
When the flower is expanded the two pollinia, 
united into a single mass, lie quite loose on the 
clinandrum and under the anther-case. The labellum 
embraces the column, leaving a passage in front. The 
middle portion of the labellum (as may be seen in 
fig. A) is thickened, and extends up as far as tlie 
top of the stigma. The lowest part of the column 
is developed into a saucer-like nectary, which secretes 
honey. 

As an insect forces its way into one of these flowers, 
the labellum, which is elastic, will yield, and the 
projecting lip of the anther will protect the rostellum 
from being disturbed ; but as soon as the insect 
retreats, the lip of the anther wdll be lifted up, and 
the viscid matter from the rostellum forced into the 
anther, gluing the pollen-mass to the insect, which 
will thus be transported to another flower. I easily 
imitated this action ; but as the pollen-masses have 
no caudicle and lie rather far back within the clinan- 
drum beneath the anther, and as the matter from the 
rostellum is not highly viscid, they were sometimes 
left behind. 

Owing to the inclination of the base of the clinan- 
drum, and owing to the length and elasticity of the 
filament, as soon as the anther is lifted up it always 
springs forward, over the rostellum, and remains 
hanging there with its lower empty surface (fig. C) sus- 
pended over the summit of the stigma. The filament 
now stretches across the space (see fig. B) which 
was originally covered by the anther. Several times, 
having cut off all the petals and labellum, and laid 
the flower under the microscope, I raised the lip of the 
anther with a needle, without disturbing the rostellum, 
and saw the anther assume, with a spring, the position 



Chap. V. DENDROBIUM CHRYSANTIIUM. 141 

represented sideways in fig. B, and frontways in fig. 
C. By this springing action the anther scoops the 
pollinium out of the concave clinandrum, and pitches 
it up in the air, with exactly the right force so as to 
fall down on the middle of the viscid stigma, where it 
adheres. 

Under nature, however, the action cannot be as thus 
described, for the labellum hangs downwards ; and to 
understand what follows, the drawing should be placed 
in an almost reversed position. If an insect failed to 
remove the pollinium by means of the viscid matter 
from the rostellum, the pollinium would first be jerked 
downwards on to the protuberant surface of the label- 
lum, placed immediately beneath the stigma. But it 
must be remembered that the labellum is elastic, and 
that at the same instant that the insect, in the act of 
leaving the flower, lifts up the lip of the anther, and 
so causes the pollinium to be shot out, the labellum 
will rebound back, and striking the pollinium will 
pitch it upwards, so as to hit the adhesive stigma. 
Twice I succeeded in effecting this by imitating the 
retreat of an insect, with the flower held in its natural 
position ; and on opening it, found the pollinium 
glued to the stigma. 

This view of the use of the elastic filament, seeinof 
how complicated the action must be, may appear 
fanciful ; but we have seen so many and such curious 
adaptations, that I cannot believe the strong elasticity 
of the filament and the thickening of the middle part 
of the labellum to be useless points of structure. If 
tlie action be as I have described, we can perceive 
their meaning, for it would be an advantage to the 
plant that its single large pollen-mass should not be 
wasted, supposing that it failed to adhere to an insect 
by means of the viscid matter from the rostellum. 



142 EPIDENDKE^. Chap. V. 

This (iontrivance is not common to all the species of 
the genus ; for in neither D. higihhum nor D. formosum 
was the filament of the anther elastic, nor was the 
middle line of the labellum thickened. In B. tortile 
the filament is elastic; but as I examined only a 
sinsrle flower, and before I had made out the structure 
of D. chrijsantlium, I cannot say how it acts. 

Mr. Anderson states * that on one occasion the flowers 
of his Dendrohium cretaceum did not expand, and yet 
they produced capsules, one of which he sent me. 
Almost all the numerous seeds in this capsule con- 
tained embryos, thus differing greatly from the cases 
presently to be given of the self-fertilised seeds from 
the non-expanded flowers of a Cattleya. Mr. Anderson 
remarks that Dendrobiums are the sole representatives 
of the Malaxese which, as far as he has seen, spon- 
taneously form capsules. He likewise states that in 
the immense group of the Vandese, hereafter to be 
described, none of the species under his care, with 
the exception of some belonging to the sub-division 
of the BrassidsB and of Sarcanthus farisliiiy has ever 
spontaneously produced a capsule. 

EPIDENDKE^. 

The Epidendrese and Malaxese are characterised by 
the pollen-grains cohering into large waxy masses. 
In the latter of these groups the pollinia are said not 
to be furnished with caudicles, but this is not uni- 
versally the case, for they exist in MasdevalUa fenes- 
trata and some other species in an efficient condition, 
although unattached and of minute size. In the 
Epidendreai, on the other hand, free or unattached 
caudicles are elways present. For my purpose these 

* ' Journal v.i Horticulture,' 1S63, pp. 20G, 287. 



Chap. V. CATTLEYA. 143 

two great tribes might have been run together ; as the 
distinction drawn from the presence of caudicles does 
not always hold good. But difficulties of this nature 
are frequently encountered in the classification of 
largely developed or so-called natural groups, in which 
there has been comparatively little extinction. 

I will begin with the genus Cattleya, of which I 
have examined several species. These are fertilised 
in a very simple manner, different from that in any 
British Orchid. The rostellum (r, fig. 22, A, B) is a 
broad, tongue-shaped projection, which arches slightly 
over the stigma ; the upper surface is formed of smooth 
membrane ; the lower surface together with the central 
portion (originally a mass of cells) consists of a very 
thick layer of viscid matter. This viscid mass is 
hardly separated from the viscid matter thickly coating 
the stigmatic surface which lies close beneath the ros- 
tellum. The projecting upper lip of the anther rests 
on, and opens close over the base of the upper mem- 
branous surface of the tongue-shaped rostellum. The 
anther is kept closed by a spring, at its point of at- 
tachment on the top of the column. The poUinia 
consist of four (or eight in Cattleya crispa) waxy 
masses, each furnished (see figs. C and D) with a 
ribbon-like tail, formed of a bundle of highly elastic 
threads, to which numerous separate pollen-grains are 
attached. The pollen therefore consists of two kinds, 
namely, waxy masses and separate though compound 
grains (each, as usual, consisting of four) united by 
elastic threads. This latter kind of pollen is identical 
with that of Epipactis and other Neottea3.* These tails, 
with their appended pollen-grains, act as caudicles, 

* The polK-n-masses of Bh tia published by Lindley in his • II- 
are admirably represented on a lustrations.' 
large scale in Hauer's drawings, 



144 



EPIDENDKE^. 



Chap. V. 



and are thus designated, for they serve as the means 
for the removal of the larger waxy masses from the 
anther-cells. The tips of the caudicles are generally 
reflexed, and in the mature flower protrude a little 



Fig. 






CArrLEYA. 


a. 
b. 

P- 
r. 


anther. 

spring at the top of the column. 

pollen-masses. 

rostellum. 


B. { 


s. 
col 

I. 


stigma, 
column, 
labellum. 


C. 1 


g- 

A. 


nectary. 

ovarium, or germen. 
Front view of column, with all 
the sepals and petals removed. 


D. . 



Section and lateral view of th(3 
flower, with all the sepals and 
petals removed, except the bi- 
sected labellum shown only in 
outline. 
C. Anther viewed on the under side, 
showing the four caudicles with 
the four pollen-masses beneath. 

A single pollinium, viewed later- 
ally, showing the pollen-mass 
and caudicle. 



way out of the anther-case (see fig. A) lying on the 
base of the upper membranous lip of the rostellum. 
The labellum enfolds the column, making the flower 



Chap. V. CATTLE Y A. 145 

tubular, and its lower part is produced into a nectary, 
which penetrates the ovarium. 

Kow' for the action of these parts. If any body of 
size proportional to that of the tubular flower be 
forced into it — a dead humble-bee acts very well — the 
tongue-shaped rostellum is depressed, and the object 
often gets slightly smeared with viscid matter ; but 
in withdrawing it, the rostellum is upturned, and a 
surprising quantity of viscid matter is forced over the 
edges and sides, and at the same time into the lip of 
the anther, which is also slightly raised by the up- 
turning of the rostellum. Thus the protruding tips 
of the caudicles are instantly glued to the retreating 
object, and the pollinia are withdrawn. This hardly 
ever failed to occur in my repeated trials. A living 
bee or other large insect alighting on the fringed 
edge of the labellum, and scrambling into the flower, 
would depress the labellum and would be less likely 
to disturb the rostellum, until it had sucked the 
nectar and began to retreat. When a dead bee, with 
the four waxy balls of pollen dangling by their 
caudicles from its back, is forced into another flower, 
some or all of them are caught with certainty by the 
broad, shallow, and highly viscid stigmatic surface, 
which likewise tears off the grains of pollen from the 
threads of the caudicles. 

That living humble-bees can thus remove the 
pollinia is certain. Sir W. C. Trevelyan sent to Yir. 
Smith of the British Museum a Bomhns liortorum, 
which was forwarded to me — caught in his hothouse, 
where a Cattleya was in flower— with its whole bade, 
between the wings, smeared with dried viscid matter, 
and with the four pollinia attached to it by their 
caudicles, ready to be caught by the stigma of any 
other flower if the bee had entered one. 



146 EriDENDREiE. Chap. V 

Those species which I have examined of Laelia, 
Leptotcs, Sophronitis, Barkeria, Phaius, Evelyna, 
Bletia, Chysis, and Coelogyne, resemble Cattleya in 
the caudicles of the pollinia being free, and in the 
viscid matter from the rostellum not coming into 
contact with them without mechanical aid, as well as 
in their general manner of fertilisation. In Coelogyne 
crisfata the upper lip of the rostellum is much elon- 
gated. In Evehjna carivata and Chysis eight balls of 
waxy pollen are all united to a single caudicle. In 
Barkeria the labellum, instead of enfolding the column, 
is pressed against it, and this would effectually compel 
insects to brush against the rostellum. In Epidendrum 
we have a slight difference ; for the uj)per surface of 
the rostellum, instead of permanently remaining mem- 
branous, as in the above-named genera, is so tender 
that by a touch it breaks up, together with the whole 
lower surface, into a mass of viscid matter. In tliis 
case the whole of the rostellum, together with the 
adherent pollinia, must be removed by insects as they 
retreat from the flower. I observed in E. glaucum that 
viscid matter exuded from the upper surface of the 
rostellum when touched, as happens with Epipactis. 
In fact it is difficult to say, in these cases, whether 
the upper surface of the rostellum should be called 
membrane or viscid matter. With Chysis this matter 
sets nearly hard and dry in twenty minutes, and 
quite so in thirty minutes after its removal from the 
rostellum. 

In Epidendrum floribundum there is a rather greater 
difference : the anterior horns of the clinandrum (i. e. 
the cup on the summit of the column in which the 
pollinia lie) approach each other so closely as to 
adhere to the two sides of the rostellum, which con- 
sequently lies in a nick, with the pollinia seated over 



Chap V. CATTLEYA. 147 

it ; and as, in this species, the upper surface of the 
rostellum resolves itself into yiscid matter, the cau- 
dicles of the pollinia become glued to it without any 
mechanical aid. The pollinia, though thus attached, 
cannot, of course, be removed from their anther-cells 
without the aid of insects. In this species it seems 
possible (though, from the position of parts, not 
probable) that an insect might drag the pollinia out 
and leave them on the stigma of the same flower. In 
all the other species of Epidendrum which I examined, 
and in all the above-mentioned genera, it is evident 
that the viscid matter has to be forced upwards into 
the lip of the anther by a retreating insect, which 
would thus necessarily carry the pollinia from one 
flower to the stigma of another. 

Nevertheless, self-fertilisation takes place in some 
Epidendreae. Dr. Criiger says* that "we have in 
Trinidad three plants belonging to this family (a 
Schomburgkia, Cattleya, and Epidendron) which rarely 
open their flowers, and they are invariably found to be 
impregnated when they do open them. In these cases 
it is easily seen that the pollen-masses have been acted 
on by the stigmatic fluid, and that the pollen-tubes 
descend from the pollen-masses in situ down into the 
ovarian canal." Mr. Anderson, a skilful cultivator of 
Orchids in Scotland, also states that several of his 
Epidendreae fertilise themselves spontaneously.f In 
the case of Cattleya crispa, the flowers sometimes do 
not expand properly ; nevertheless they produce cap- 
sules, one of which he sent to me. It contained an 
abundance of seeds, but on examination I found that 



..* ' '^^'^^^' Linn. Soc. Bot.' vol. paper Mr. Gosse gives an account 

viii. 1864, p. 131. of his microscopical examination 

t 'Journal of Horticulture,' of the self- fertilised seeds. 
1863, p. 206 and 287 : in the latter 



148 EPIDENDEEJ2. Chap. V. 

only about one per cent, contained an embryo. Similar 
seeds were more carefully examined by Mr. Gosse, who 
found that two per cent, contained an embryo. About 
twenty-five per cent, of the seeds from a self-fertilised 
capsule of L^lia cinnabarina, also sent to me by 
Mr. Anderson, were found to be good. It is therefore 
doubtful whether the capsules spontaneously self-ferti- 
lised in the West Indies, as described by Dr. Cruger, 
were fully and properly fertilised. Fritz Miiller in- 
forms me that he has discovered in South Brazil 
an Epidendrum which bears three pollen-producing 
anthers, and this is a great anomaly in the order. 
This species is very imperfectly fertilised by insects ; 
but by means of the two lateral anthers the flowers 
are regularly self-fertilised. Fritz Miiller assigns good 
reasons for his belief that the appearance of the two 
additional anthers in this Epidendrum, is a case of 
reversion to the primitive condition of the whole 
group.* 

♦ See also ' Bot. Zeitnng,' 1869, p. 226, and 1870, p. 152. 



Chap. VI. STRUCTURE OF COLUMIf. 149 



CHAPTEE YI. 



VANDE^. 



Structure of the columu and pollinia — Importance of the elasticity of 
the pedicel; its power of movement — Elasticity and strength of the 
caudicles — Calanthe with lateral stigmas, manner of fertilisation — 
Angrsecum sesquipedale, wonderful length of nectary — Species with 
the entrance into the stigmatic chamber much contracted, so that 
the pollen-masses can hardly be inserted— Coryanthes, extraordinary 
manner of fertilisation. 

We now come to the immense tribe of the Yandese, 
which includes many of the most magnificent produc- 
tions of our hothouses, but like the Epidendrese has 
no British representative. I have examined twenty- 
nine genera. The pollen consists of waxy masses, as 
in the two last tribes, and each ball of pollen is 
furnished with a caudicle, which becomes, at an early 
period of growth, united to the rostellum. The cau- 
dicle is seldom attached directly to the viscid disc, as 
in most of the Ophrese, but to the upper and posterior 
surface of the rostellum ; and this part is removed by 
insects, together with the disc and pollen-masses. The 
sectional diagram (fig. 23), with the parts separated, 
will best explain the type-structure of the Yandese. 
As in the rest of the Orchidese there are three con- 
fluent pistils; of these the dorsal one (2) forms the 
rostellum arching over the two others (3) which unite 
to form a single stigma. On the left hand we have 
the filament (1) bearing the anther. The anther opens 
at an early period, and the tips of the two caudicles 
(but only one caudicle and one pollen-mass are re- 



150 



YANDEX. 



Chap. VL 



presented in the diagram) protrude in a not fully- 
hardened condition through a small slit, and adhere to 
the back of the rostellum. The upper surface of the 
rostellum is generally hollowed out for the reception 
of the pollen-masses ; it is represented as smooth in 
the diagram, but is really often furnished with crests 



Fig. 23. 
anther. caudicle 



,.- pedicel of 
rostellum. 





12 3 

Imaginary Section, illustrative of the structure of the column in the 

VANDKiE. 



(I.) The filament, bearing the an- 
ther with its pollen-masses ; 
the anther is represented after 
it has opened along its whole 
under surface, so that the 
section shows only the dorsal 
surface. 



(2.) The upper pistil, with the 

upper part moditied mto the 

rostellum. 
(3.) The two lower confluent pistils, 

bearing the two conflueut 

stigmas. 



or knobs for the attachment of the two caudicles. 
The anther afterwards opens more widely along its 
under surface, and leaves the two pollen-masses un- 
attached, excepting by their caudicles to the rostellum. 
During an early period of growth, a remarkable 
change has been going on in the rostellum : either its 
extremity or its lower surface becomes excessively 
viscid (forming the viscid disc), and a line of separa- 



Chap. TI. STRUCTURE OF COLUMN. 151 

tion, at first appearing as a zone of hyaline tissue, is 
gradually formed, which sets free the disc, as well as 
the whole upper surface of the rostellum, as far back 
as the point of attachment of the caudicles. If any 
object now touches the viscid disc, it, together with 
the whole back of the rostellum, the caudicles and 
pollen-masses, can all be readily removed together. 
In botanical works the whole structure between the 
disc or viscid surface (generally called the gland) and 
the balls of pollen is designated as the caudicle ; but 
as these parts play an essential part in the fertilisation 
of the flower, and as they are fundamentally different 
in their origin and in their minute structure, I shall 
call the two elastic ropes, which are developed strictly 
within the anther-cells, the caudicles ; and the portion 
of the rostellum to which the caudicles are attached 
(see diagram), and which is not viscid, the pedicel. 
The viscid portion of the rostellum I shall call, as 
heretofore, the viscid surface or disc. The whole may 
be conveniently spoken of as the poUinium. 

In the Ophrese we have (except in 0. pyramidalis 
and a few other species) two separate viscid discs. In 
the Yandeoe, with the exception of Angra^cum, we have 
only one disc. The disc is naked, or is not enclosed 
in a pouch. In Habenaria the discs, as we have seen, 
are separated from the two caudicles by short drum- 
like pedicels, answering to the single and generally 
much more largely developed pedicel in the Yandeae. 
In the Ophreae the caudicles of the pollinia, though 
elastic, are rigid, and serve to place the packets of 
pollen at the right distance from the insect's head or 
proboscis, so as to reach the stigma. In the Yandea) 
this end is gained by the pedicol of the rostellum. 
The two caudicles in the Yandese are embedded and 
attached within a deep cleft in the pollen-masses. 



152 VANDE^. Chap. VI 

and until stretched are rarely visible, for the pollen- 
masses lie close to the pedicel of the rostellum. These 
caudicles answer both in position and function to the 
elastic threads, by which the packets of pollen are tied 
together in the Ophreae, at the point where they become 
confluent ; for the function of the true caudicle in the 
Vandeae is to break when the masses of pollen, trans- 
ported by insects, adhere to the stigmatic surface. 

In many Vandeae the caudicles are easily ruptured, 
and the fertilisation of the flower, as far as this point 
is concerned, is a simple affair ; but in other cases their 
strength, and the length to which they can be stretched 
before they break, are surprising. I was at first per- 
plexed to understand what purpose these qualities 
could serve. The explanation probably is that the 
pollen-masses in this tribe are very precious objects ; 
in most of the genera a flower produces only two, and 
judging from the size of the stigma both are generally 
left adhering to it. In other genera, however, the 
orifice leading into the stigma is so small that probably 
only one pollen-mass is left on it, and in this case the 
pollen from one flower would suffice to fertilise two 
flowers, but never a greater number. From the large 
size of the flowers of many of the Vandeae, they no 
doubt are fertilised by large insects, and these whilst 
flying about would be likely to brush away and lose 
the pollinia attached to them, unless the caudicles were 
very strong and highly elastic. So again, when an 
insect thus provided visited a flower either too young, 
with its stigma not yet sufficiently adhesive, or one 
already impregnated, with its stigma beginning to dry, 
the strength of the caudicle would prevent the pollen- 
masses from being uselessly removed and lost. 

Although the stigmatic surface is astonishingly 
adhesive at the proper period in many of these Orchids, 



Chap. VI. SHAPE OF THE POLLINIA. 153 

for instance, in Phalaenopsis and Saccolabium, yet when 
I inserted their pollinia attached to a rough object into 
the stigmatic chamber, they did not adhere with suffi- 
cient force to prevent their removal from the object. I 
even left them for some little time in contact with the 
adhesive surface, as an insect would do whilst feeding ; 
but when I pulled the pollinia straight out of the 
stigmatic chamber, the caudicles, though they were 
stretched to a great length, did not rupture, nor did 
their attachment to the object yield so that the balls 
of pollen were withdrawn. It then occurred to me 
that an insect in flying away would not pull the 
pollinia straight out of the chamber, but would pull 
at nearly right angles to its orifice. Accordingly I 
imitated the action of a retreating insect, and dragged 
the pollinia out of the stigmatic chamber at right 
angles to its orifice; and now the friction on the 
caudicles thus caused, together with the adhesiveness 
of the stigmatic surface, generally sufficed to rupture 
them; the pollen-masses being left on the stigma. 
Thus, it seems that the great strength and extensi- 
bility of the caudicles, which, until stretched, lie em- 
bedded within the pollen-masses, serve to protect the 
pollen-masses from being accidentally lost by an insect 
whilst flying about, and yet, by friction being brought 
into play, allow them at the proper time, to be left 
adhering to the stigmatic surface ; the fertilisation of 
the flower being thus safely effected. 

The discs and pedicels of the pollinia present great 
diversities in shape, and an apparently exhaustless 
number of adaptations. Even in species of the same 
genus, as in Oncidium, these parts differ greatly. I 
here give a few figures (fig. 24), taken almost at hazard, 
The pedicel generally consists, as far as I have seen, 
of a thin ribbon-shaped membrane (fig. A) ; sometimes 
8 



154 



VANDE.'R. 



Chap. Y1. 



it is almost cylindrical (fig. C) but often of the moat 
diversified shapes. The pedicel is generally nearly 
straight, but in Miltonia dowesii it is naturally curved ; 
and in some cases, as we shall immediately see, it 
assumes, after removal, various shapes. The extensible 
and elastic caudicles, by which the pollen-masses are 
attached to the pedicel, are barely or not at all visible, 
being embedded in a cleft or hollow within each 
pollen-mass. The disc, which is viscid on the under 
side, consists of a piece of thin or thick membrane of 

Fig. 2k 




POLLINIA OF VaNDE^. 



B. Pollinium ot Brassia maculata 
(copied from Bauer). 

C. Pollinium of Stanhopea saccata 
after depression. 

D. Pollinium of Sarcanthus tereti- 
folius after depression. 



d. viscid disc 

ped. pedicel. 

«. pollen-masses. 

Tbe caudicles, being embedded within 

the pollen-masses, are not shown. 
A. Pollinium of Oncidinm grande 

after partial depression. | 

varied forms. In Acropera it is like a pointed cap ; 
in some cases it is tongue-shaped, or heart-shaped 
(fig. C), or saddle-shaped, as in some Maxillarias, or 
like a thick cushion (fig. A), as in many species of 
Oncidium, with the pedicel attached at one end, instead 
of, as is more usual, nearly to the centre. In Angrsecum 
distichum and sesquipedale the rostellum is notched, 
and two separate, thin, membranous discs can be 
removed, each carrying by a short pedicel a pollen- 
mass. In Sarcanthus teretif alius tlie disc (fig. D) is 



Chap. VI. MOVEMENTS OF THE POLLINIA. 155 

very oddly shaped; and as the stigmatic chamber 
is deep and likewise curiously shaped, we are led to 
believe that the disc is fastened with great precision 
to the square projecting head of some insect.* 

In most cases there is a plain relation between the 
length of the pedicel and the depth of the stigmatic 
chamber, into which the pollen-masses have to be 
inserted. In some few cases, however, in which a long 
pedicel and a shallow stigma co-exist, we shall presently 
meet with curious compensating actions. After the 
disc and pedicel have been removed, the shape of the 
remaining part of the rostellum is of course altered, 
being now slightly shorter and thinner, and sometimes 
notched. In Stanhopea, the entire circumference of 
the extremity of the rostellum is removed, and a thin, 
pointed, needle-like process alone is left, which origin- 
ally ran up the centre of the disc. 

If we now turn to the diagram (fig. 23, p. 150), and 
suppose the rectangularly bent rostellum to be thinner 
and the stigma to lie closer beneath it than is there 
represented, we shall see that, if an insect with a poUi- 
nium attached to its head were to fly to another flower 
and occupy exactly the same position which it held 
whilst the attachment was effected, the pollen-masses 
would be in the right position for striking the stigma, 
especially if, from their weight,- they were to become 
in the least degree depressed. This is all that takes 
place in Ly caste sJcinnerii, Gymhidium giganteum, 
Zygopetalum mackai, Angrwcum ebarneu77i, Miltonia 
dowesii, in a Warrea, and, I believe, in Galeandra 
funJcii. But if in our diagram we suppose, for instance. 



» I may here remark that Del- dinm, Epidendnim, Phaius, and 

pino (' Fecondazione nelle Piante,* Dendrobium, and is able to con« 

Firenze, 1867, p. 19) says he has firm in general my statements, 
examined flowers of Vanda, Ouci- 



156 YANDEX. Chap. VL 

the stigma to be seated at the bottom of a deep cavity, 
low down in the column, or the anther to be seated 
higher up, or the pedicel of the rostellum to slope 
more upwards, &c. — all of which contingencies occur 
in various species, — in such cases, an insect with a 
pollinium attached to its head, if it flew to another 
flower, would not place the pollen-masses on the 
stigma, unless their position had become greatly 
changed after attachment. 

This change is effected in many Vandese in the same 
manner as is so general with the Ophreae, namely, by a 
movement of depression in the pollinium in the course 
of about half a minute after its removal from the 
rostellum. I have seen this movement conspicuously 
displayed, generally causing the pollinium to rotate 
through about a quarter of a circle, in several species 
of Oncidium, Odontoglossum, Brassia, Yanda, Aerides, 
Sarcanthus, Saccolabium, Acropera, and Maxillaria. 
In Bodriguezia suaveolens the movement of depression 
is remarkable from its extreme slowness ; in Euloiohia 
viridis from its small extent. Mr. Charles Wright, in 
a letter to Professor Asa Gray, says that he observed 
in Cuba a pollinium of an Oncidium attached to a 
humble-bee, and he concluded at first that I was 
completely mistaken about the movement of depres- 
sion ; but after several hours it moved into the proper 
position for fertilising the flower. In some of the 
cases above specified in which the pollinia apparently 
undergo no movement of depression, I am not sure that 
there was not a very slight one after a time. In the 
various Ophrese the anther-cells are sometimes seated 
exteriorly and sometimes interiorly with respect to 
the stigma ; and there are corresponding outward and 
inward movements in the pollinia : but in the Vandeae 
the anther-cells always lie, as far as I have seen, 



Chap. VL MOVEMENTS OF THE POLLINIA. 157 

directly over the stigma, and the movement of the 
pollinium is always directly downwards. In Calanthe, 
however, the two stigmas are placed exteriorly to the 
anther-cells, and the pollinia, as we shall see, are made 
to strike them by a peculiar mechanical arrangement 
of the parts. 

In the Ophrea3 the seat of contraction, which causes 
the act of depression, is in the upper surface of the 
viscid disc, close to the point of attachment of the 
caudicles : in most of the Yandeae the seat is likewise 
in the upper surface of the disc, but at the point 
where the pedicel is united to it, and therefore at a 
considerable distance from the point of attachment of 
the true caudicles. The contraction is hygrometric, but 
to this subject I shall return in the ninth chapter ; 
therefore the movement does not take place until the 
pollinium has been removed from the rostellum, and 
the point of union between the disc and pedicel has 
been exposed for a few seconds or minutes to the air. 
If, after the contraction and consequent movement of 
the pedicel, the whole body be placed into water, the 
pedicel slowly moves back and resumes its former 
position with respect to the viscid disc. When taken 
out of water, it again undergoes the movement of de- 
pression. It is of importance to notice these facts, as 
we thus get a test by which this movement can be 
distinguished from certain other movements. 

In Max'illaria ornithorhyncha, we have a unique case. 
The pedicel of the rostellum is much elongated, and 
is entirely covered by the produced front lip of the 
anther, and is thus kept damp. When removed it 
bends quickly backwards on itself, at about its central 
point, and thus becomes only half as long as it was 
before. When placed in water it resumes its original 
straight form. If the pedicel had not been in some 



158 VANDE.E. Chap. VI. 

manner shortened, it is hardly possible that the flower 
could have been fertilised. After this movement, the 
pollinium attached to any small object can be inserted 
into the flower, and the balls of pollen readily adhere 
to the stigmatic surface. Here we have an instance 
of one of those compensating actions in the poUinia, 
before alluded to, in relation to the shallowness of 
the stigma. 

In some cases, besides hygrometric movements, 
elasticity comes into play. In Aerides odorata and 
virens, and in an Oncidium {roseum ?), the pedicel of 
the rostellum is fastened down in a straight line, at 
one extremity by the disc, and at the other by the 
anther ; it has, however, a strong elastic tendency to 
spring up at right angles to the disc. Consequently, 
if the pollinium, attached by its viscid disc to some 
object, is removed from the anther, the pedicel instantly 
springs up and stands at nearly right angles to its 
former position, with the pollen-masses carried aloft. 
This has been noticed by other observers ; and I agree 
with them that the object gained is to free the pollen- 
masses from the anther-cells. After this upward elastic 
spring, the downward hygrometric movement imme- 
diately commences, which, oddly enough, carries the 
pedicel back again into almost exactly the same 
position, relatively to the disc, which it held whilst 
forming part of the rostellum. In Aerides the end of 
the pedicel, to which the pollen-masses are attached 
by short dangling caudicles, after springing up, remains 
a little curved upwards; and this curvature seems 
well adapted to drop the pollen-masses into the deep 
stigmatic cavity over the ledge in front. The differ- 
ence between the first elastic and the second or re- 
versed hygrometric movement, was well shown by 
placing the pollinium of the above Oncidium into 



Chap. VI. MOVEMENTS OF THE rOLLlNIA. 159 

water, after both movements had taken phice ; and 
the pedicel then moved into the same position which 
it had at first assumed through its elasticity ; this 
movement not being in any way affected by the 
water. When taken out of water the hygrometric 
movement of depression soon commenced for tlie 
second time. 

In Bodrigiiezia secunda there was no hygrometric 
movement of depression in the pedicel as in the before- 
mentioned R. suaveolenSy but there was a rapid down- 
ward movement, due to elasticity, and of this I have 
seen no other instance ; for when the pedicel was put 
into water it showed no tendency to recover its original 
position, as occurred in many other cases. 

In Phal^nopsis grandifiora and amahilis the stigma 
is shallow and the pedicel of the rostellum long. 
Some compensating action is therefore requisite, which, 
differently from that in Maxillaria ornitJwrhyncJia is 
effected by elasticity. There is no movement of de- 
pression ; but, when the pollinium is removed, the 
straight pedicel suddenly curls up in the middle, thus 
( — '^— ■ ) : the full-stop on the left hand may re- 
present the balls of pollen, and the thick hyphen to 
the right may be supposed to represent the triangu- 
larly shaped disc. The pedicel does not straighten 
itself when placed in water. The end carrying the 
balls of pollen is a little raised up after this elastic 
movement, and the pedicel, with one end raised, and 
with the middle part upwardly bowed, is well adapted 
to drop the pollen-masses into the deep stigmatic 
cavity, over a ledge in front. Fritz Midler informs 
me of a case in which the shortening of a very long 
pedicel is effected partly by elasticity and partly by a 
hygrometric movement. A small Ornithocephalus, 
growing in South Brazil, has a very long pedicel, 



160 



VANDE^. 



Chap. IV. 



which is shown closely attached to the rostellum in 
the accompanying figure A. 

Fig. 25. 




POLLINIUM OF Ornithocepiialus. (From a sketch by Fritz Miiller.) 



A. Pollinium still attached to the 

rostellum with the pollen- 
mass still lying in the cli- 
nandrum on the summit of 
the column. 

B. Pollinium in the position which 



it first assumes from the elas- 
ticity of the pedicel. 
Pollinium in the position ul- 
timately assumed from the 
hygrometric movement. 



The pedicel when freed suddenly bends into the 
form represented at B, and soon afterwards owing to 
the hygrometric contraction curls up into the odd 
figure shown at C. When placed in water it resumes 
the form represented at B. 



Chap. VI. 



CALANTHE MASUCA. 



161 



In Gdlanthe masuca and the hybrid G. dominii the 
structure is very different to what it is in most other 
VandesB. We here have two oval, pit-like stigmas 
on each side of the rostellum (fig. 26). The viscid 
disc is oval (fig. B), and has no pedicel, but eight 
masses of pollen are attached to it by very short and 

Fig. 26. 




c V.''^ 



Calanthe masuca. 



pollen-masses. 

the two stigmas. 

mouth of nectary. 

labellum. 

viscid disc. 

in fig. C, clinandrura the pol- 
len-masses being removed. 
Flower viewed from above, with 
the anther -case removed, 
showing the eight pollen- 
masses in their proper position 
within the clinandrura. All 
the sepals and petals have been 
cut away except the labellum. 



B. Pollen-masses attached to the 

viscid disc, seen from the 
under side. 

C. Flower in same position as in A, 

but with the disc and pollen- 
masses removed, and now 
showing the deeply notched 
rostellumand the empty clin- 
andrura in which the pollen 
raasses lay. Within the left- 
hand stigma two pollen- 
masses may be seen adhering 
to its viscid surface. 



easily ruptured caudicles. These pollen-masses radiate 
from the disc like the leaves of a fan. The rostellum 
is broad, and its sides slope on each side towards the 
lateral pit-like stigmas. When the disc is removed 
the rostellum is seen (fig. C) to be deeply notched 
in the middle. The labellum is united to the column 
almost up to its summit, leaving a passage (w, A) to 



162 VANDE^. Chap. VL 

the long nectary close beneath the rostellum. The 
labellum is studded with singular, wartlike, globular 
excrescences. 

If a thick needle be inserted into the mouth of the 
nectary (fig. A), and then withdrawn, the viscid disc 
is removed, bearing with it the elegant fan of radiating 
pollen-masses. These undergo no change in position. 
But if the needle be now inserted into the nectary of 
another flower, the ends of the pollen-masses neces- 
sarily hit the upper and laterally sloping sides of the 
rostellum, and, glancing off both ways, strike down 
into the two lateral pit-like stigmas. The thin cau- 
dicles being easily ruptured, the pollen-masses are left 
adhering like little darts to the viscid surface of both 
stigmas (see left-hand stigma in fig. C), and the fertili- 
sation of the flower is completed in a simple manner 
pleasing to behold. 

I should have stated that a narrow transverse rim of 
stigmatic tissue, beneath the rostellum, connects the 
two lateral stigmas ; and it is probable that some of 
the middle pollen-masses may be inserted through the 
notch in the rostellum, so as to adhere to this rim. 
I am the more inclined to this opinion from having 
found in the elegant Calantlie vestita the rostellum 
extending so widely over the two lateral stigmas, that 
apparently all the pollen-masses must be inserted 
beneath its surface. 

The Angrdecum sesqiiipedaJey of which the large six- 
rayed flowers, like stars formed of snow-white wax, 
have excited the admiration of travellers in Madagascar, 
must not be passed over. A green, whip-like nectary 
of astonishing length hangs down beneath the label- 
lum. In several flowers sent me by Mr. Bateman I 
found the nectaries eleven and a half inches long, with 
only the lower inch and a half filled with nectar. 



Chap. VI. ANGlliECUM SESQUIPEDALE. 163 

What can be the use, it may be asked, of a nectary of 
such disproportionate length ? We shall, I think, see 
that the fertilisation of the plant depends on this 
length, and on nectar being contained only within the 
lower and attenuated extremity. It is, however, sur- 
prising that any insect should be able to reach the 
nectar. Our English sphinxes have proboscides as long 
as their bodies ; but in Madagascar there must be 
moths with proboscides capable of extension to a length 
of between ten and eleven inches! This belief of 
mine has been ridiculed by some entomologists, but we 
now know from Pritz Miiller * that there is a sphinx - 
moth in South Brazil which has a proboscis of nearly 
sufficient length, for when dried it was between ten 
and eleven inches long. When not protruded it is 
coiled up into a spiral of at least twenty windings. 

The rostellum is broad and foliaceous, and arches 
rectangularly over the stigma and over the orifice of 
the nectary : it is deeply notched by a cleft enlarged 
or widened at the inner end. Hence the rostellum 
nearly resembles that of Calanthe after the disc has 
been removed (see fig. 26, C). The under surfaces of 
both margins of the cleft, near their ends, are bordered 
by narrow strips of viscid membrane, easily removed ; 
so that there are two distinct viscid discs. A short 
membranous pedicel is attached to the middle of the 
upper surface of each disc ; and the pedicel carries a 
pollen-mass at its other end. Beneath the rostellum 
a narrow, ledge-like, adhesive stigma is seated. 

I could not for some time understand how the 
pollinia of this Orchid were removed, or how the 
stigma was fertilised. I passed bristles and needles 



* See letter v\ith a drawing by Hermann Miiller, 'Nature,* 187J^, 
p. 223. 



164 YANDEX. CiiAP. VI. 

down the open entrance into the nectary and through 
the cleft in the rostellum with no result. It then 
occurred to me that, from the length of the nectary, 
the flower must be visited by large moths, with a 
proboscis thick at the base ; and that to drain the last 
drop of nectar, even the largest moth would have to 
force its proboscis as far down as possible. Whether 
or not the moth first inserted its proboscis by the open 
entrance into the nectary, as is most probable from the 
shape of the flower, or through the cleft in the ros- 
tellum, it would ultimately be forced in order to drain 
the nectary to push its proboscis through the cleft, 
for this is the straightest course ; and by slight pressure 
the whole foliaceous rostellum is depressed. The dis- 
tance from the outside of the flower to the extremity of 
the nectary can be thus shortened by about a quarter 
of an inch. I therefore took a cylindrical rod one- 
tenth of an inch in diameter, and pushed it down 
through the cleft in the rostellum. The margins 
readily separated, and were pushed downwards together 
with the whole rostellum. When I slowly withdrew the 
cylinder the rostellum rose from its elasticity , and 
the margins of the cleft were upturned so as to clasp 
the cylinder. Thus the viseid strips of membrane on 
each under side of the cleft rostellum came into contact 
with the cylinder, and firmly adhered to it ; and the 
pollen-masses were withdrawn. By this means I suc- 
ceeded every time in withdrawing the pollinia ; and 
it cannot, I think, be doubted that a large moth would 
thus act ; that is, it would drive its proboscis up to 
the very base through the cleft of the rostellum, so as 
to reach the extremity of the nectary ; and then the 
pollinia attached to the base of its proboscis would be 
safely withdrawn. 

I did not succeed in leaving the pollen-masses on 



Chap. VI. ANGK^CUM SESQUIPEDALE. 165 

the stigma so well as I did in withdrawing them. As 
the margins of the cleft rostellum must be upturned 
before the discs adhere to a cylindrical body, during 
its withdrawal, the pollen-masses become affixed some 
little way from its base. The two discs did not always 
adhere at exactly opposite points. Now, when a moth 
with the pollinia adhering to the base of its proboscis, 
inserts it for a second time into the nectary, and exerts 
all its force so as to push down the rostellum as far as 
possible, the pollen-masses will generally rest on and 
adhere to the narrow, ledge-like stigma which projects 
beneath the rostellum. By acting in this manner with 
the pollinia attached to a cylindrical object, the pollen- 
masses were twice torn off and left glued to the stig- 
matic surface. 

If the Angrsecum in its native forests secretes more 
nectar than did the vigorous plants sent me by Mr. 
Bateman, so that the nectary ever becomes filled, small 
moths might obtain their share, but they would not 
benefit the plant. The pollinia would not be with- 
drawn until some huge moth, with a wonderfully long 
proboscis, tried to drain the last drop.* If such great 
moths were to become extinct in Madagascar, assur- 
edly the Angreecum would become extinct. On the 
other hand, as the nectar, at least in the lower part 
of the nectary, is stored safe from the depredation of 
other insects, the extinction of the Angraecum would 
probably be a serious loss to these moths. We can 
thus understand how the astonishing length of the 



* Mr. Belt suggests (*The Na- ment can thus be accounted for. 

turalist in Nicaragua,* 1874, p. I have no doubt of the truth of 

133) that the great length of the this principle, but it is hardly 

nectary of this plant serves to applicable here, as the moth has 

prevent other moths ■whi(;h are to be cianpelled to drive its pro- 

not well-adapted for the fertilisa- boscis as deeply down as posaiblo 

lion of the llowers from sucking into the dower, 
the nectar, and that its dovel"p- 



166 VANDE^. Chap. VI. 

nectary had been acqiured by successive modifications. 
As certain moths of Madagascar became larger through 
natural selection in relation to their general conditions 
of life, either in the larval or mature state, or as the 
Droboscis alone was lenfrthcned to obtain honev from 
the Angraecum and other deep tubular flowers, those 
individual plants of the Angrsecum which had the 
longest nectaries (and the nectary varies much in 
length in some Orchids), and which, consequently, 
compelled the moths to insert their proboscides up to 
the very base, would be best fertilised. These plants 
would yield most ssed, and the seedlings would 
generally inherit long nectaries; and so it would be 
in successive generations of the plant and of the moth. 
Thus it would appear that there has been a race in 
gaining length between the nectary of the Angraecum 
and the proboscis of certain moths ; but the Angrajcnm 
has trimnphed, for it flourishes and abounds in the 
forests of Madagascar, and still troubles each moth 
to insert its proboscis as deeply as possible in order to 
drain the last drop of nectar. 

I could add descriptions of many other curious 
structures in the Vandeae, more especially from the 
letters of Fritz Miiller with respect to those of Brazil ; 
but the reader would be w^earied. I must, however, 
make a few remarks on certain genera, the fertilisation 
of which remains a mystery, chiefly on account of the 
narrowness of the mouth of the stigma, as this renders 
the insertion of the pollen-masses extremely difficult. 
Two closely allied species or varieties of Acropera, viz., 
A. luteola and loddigesii have been observed by me 
during several seasons, and every detail of their struc- 
ture seems as if specially adapted to render their 
fertilisation almost impossible. I have met with hardly 



CuAi'. VI. ACROPERA, AND SOME ALLIED GENERA. 167 

any other such case, not that I fully understand the 
contrivances in any Orchid, for new and admirable 
ones become apparent, the longer I study even one of 
our commonest British species. 

The thin and elongated rostellum of Acropera projects 
at right angles to the column (see diagram, fig. 23, p. 
150) ; and the pedicel of the pollinium is of course 
equally long and much thinner. The disc consists of 
an extremely small cap, viscid within, which fits on 
the extremity of the rostellum. The viscid matter 
sets hard but slowly. The upper sepal forms a hood 
enclosing and protecting the column. The labellum 
is an extraordinary organ, baffling all description : it 
is articulated to the column by a thin strap, so elastic 
and flexible that a breath of wind sets it vibrating. 
It hangs downwards ; and the retention of this posi- 
tion seems to be of importance, for the footstalk (ova- 
rium) of each flower is curved into a semicircle, so 
as to compensate for the pendulous habit of the plant. 
The two upper petals and the lateral lobes of the 
labellum serve as guides leading into the hood-like 
upper sepal. 

The pollinium, when adhering by its disc to an 
object, undergoes the common movement of depression ; 
and this seems superfluous, for the stigmatic cavity lies 
(see diagram, fig. 23) high up at the base of the rect- 
angularly projecting rostellum. • But this is a com- 
paratively trifling difficulty ; the real difficulty lies in 
the orifice of the stigmatic chamber being so narrow 
that the pollen-masses, though consisting of thin sheets, 
can hardly be forced in. I repeatedly tried, and suc- 
ceeded only three or four times. Even after leaving 
them to dry for four hours before a fire, and thus to 
shrink a little, I rarely succeeded in forcing them 
into the stigma. I examined quite young flowers and 



168 VANDEiE. Chap. T1 

almost withered ones, for I imagined that the mouth 
of the chamber might be of larger size at some period 
of growth ; but the difficulty of insertion remained 
the same. Now when we observe that the viscid disc 
is extraordinarily small, and consequently its power of 
attachment not so firm as with Orchids having a large 
disc, and that the pedicel is very long and thin, it 
would seem almost indispensable that the stigmatic 
chamber should be unusually large for the easy 
insertion of the pollinium, instead of being much con- 
tracted. Moreover, the stigmatic surface, as Dr. Hooker 
has likewise observed, is singularly little adhesive ! 

The flowers when ready for fertilisation do not 
secrete nectar ; * but this is no difficulty, for as Dr. 
Criiger has seen humble-bees gnawing the projections 
on the labellum of the closely allied Gongora maculata, 
there can be little doubt that the distal cup-shaped 
part of the labellum of Acropera offers a similar at- 
traction to insects. After numberless trials in many 
ways, I have found that the poUinia can be removed 
with certainty only by pushing the rostellum a little 
upwards with a camel-hair brush, held in such a 
position that the tip slides along the under side of the 
rostellum, so as to brush off the little viscid cap on its 
extremity, into which the hairs enter and are glued 
fast. I further find that if the brush with a pollinium 
thus attached to its tip is pushed into and then with- 
drawn from the stigmatic cavity, the mouth of which 
is furnished with a sharp ridge, the end of the pedicel 



* Mr. Scott las observed that at no other time couLl he find a 

after the flowers of A'-ropera and trace of nectar. This exudation 

of two species in the allied genus can, therefore, be of no use to the 

of Gongora have been fertilised, plant with respect to its fertili- 

an abundance of nectar exudes sation, and must be viewed as an 

from the front of the column ; but excretion. 



Chap. VI. ACKOPERA, AND SOME ALLIED GENERA. 169 

which bears the viscid cap is often left sticking within 
the chamber, with the pollen-masses close outside. 
Many flowers were thus treated, and three of them 
produced fine capsules. Mr. Scott also succeeded in 
fertilising two flowers in the same apparently unnatural 
manner, as he likewise did on one occasion by placing 
a pollen-mass, moistened with the viscid matter from a 
distinct kind of Orchis, at the mouth of the stigmatic 
chamber. These facts lead me to suspect that an 
insect with the extremity of its abdomen produced 
into a sharp point alights on the flower, and then turns 
round to gnaw the distal portion of the labellum. In 
doing so it removes the pollinium, the viscid cap of 
which adheres to the extremity of its abdomen. The 
insect then visits another flower, by which time the 
movement of depression will have caused the pedicel 
to lie flat on its back ; and from occupying the same 
position as before, the insect will be apt to insert the 
end of its abdomen into the stigmatic chamber, and 
the viscid cap will then be scraped off by the ledge in 
front, and the pollen-masses will be left close outside, 
as in the above experiments. The whole operation 
would probably be aided by the oscillatory movement 
of the labellum whilst gnawed by an insect. This 
whole view is very improbable, but it is the only one, 
as far as I can see, which explains the fertilisation of 
the flower. 

The allied genera Gongora, Acineta, and Stanhopea 
present nearly the same difficulty from the narrowness 
of the entrance into the stigmatic chamber. Mr. 
Scott tried repeatedly but in vain to force the pollen- 
masses into the stigma of Gongora atro-purpurea and 
truncata ; but he readily fertilised them by cutting off 
the clinandrum and placing pollen-masses on the now 
exposed stigma; as he likewise did in the case of 



170 VANDE.E. Chap. VL 

Acropera. Dr. Criiger Scays* that Gongora macuJata 
"often bears fruit in Trinidad. It is visited, exclu- 
sively during the day, as far as I can see, by a splendid 
bee, probably a Euglossa, but with the tongue nearly 
twice as long as the body. The tongue passes out 
behind the abdomen, and is there curved upwards. 
As these bees only come for biting and gnawing the 
anterior side of the labellum, the protruding tongue 
touches or approaches the gland (i. e., viscid disc) at 
every retrograde movement of the insect. By this it 
can hardly fail to be loaded sooner or later with the 
pollen-masses, which are then easily inserted into the 
stigmatic cleft. I have, however, not as yet observed 
this fact." I am surprised that JDr. Criiger should 
speak of the pollen-masses being easily inserted, and I 
suppose that he must have experimented with dried 
and shrunken ones. The doubled-up, immensely elon- 
gated proboscis, projecting beyond the abdomen, would 
answer as well as a pointed extremity to the abdomen, 
which in the case of Acropera I imagine is the instru- 
ment for removing the pollen-masses ; but I presume 
that with Gongora it is not the viscid disc, but the 
broad and free ends of the pollen-masses which are in- 
serted into the stigmatic cavity. As in the case of 
Acropera, I found it scarcely possible to insert the 
pollen-masses of Gongora into the stigma ; but some 
which were removed from the anther and left exposed 
to the sun for nearly five hours, became much shrunk 
and formed thin sheets ; and these could be inserted 
without much difficulty into the cleft-like entrance 
of the stigma. The pollinia attached to an insect 
flying about in the torrid zone would shrink after a 
time ; and the delay thus caused would ensure the 



Jonrn. I.inn. Soc, Bot.' vol. viii. 18(j4, p, 131. 



Chap. VI. ACEOPEKA, AND SOME ALLIED GENERA. 171 

flowers being fertilised with pollen- from a distinct 
plant. 

With respect to Stanhopea, Dr. Criiger says* that 
in the West Indies a bee (Euglossa) often visits the 
flowers for the sake of gnawing the label lum, and he 
caught one with a pollinium attached to its back ; but 
he adds that he cannot understand how the pollen- 
masses are inserted into the narrow mouth of the stigma. 
With Stanlioi^ea oculata I found that the pollinia could 
almost always be attached to my naked or gloved 
finger, by gently sliding it down the concave surface 
of the arched column ; but this occurred only within a 
short time after the expansion of the flowers, whilst 
they are highly odoriferous. By again sliding my 
finger down the column, the pollinia were almost 
always rubbed off by the sharp edge of the stigmatic 
chamber, and were left adhering close to its entrance. 
Flowers thus treated occasionally, though rarely, 
yielded capsules. The removal of the pollinia from 
my finger seemed to depend on the existence of a 
point projecting beyond the viscid disc, and which I 
suspect is specially adapted for this purpose. If this 
be so, the pollen-masses must emit their tubes without 
being inserted into the stigmatic chamber. I may 
add that the pollen-masses shrink very little by being 
thoroughly dried, and could not in this state be easily 
inserted. 

The entrance into the stigma is in like manner, 
as I hear from Fritz Miiller, t so much contracted in 
Cirrhsea and Notylia, which belong to another sub- 
division of the Yandese, that the pollinia can be inserted 



* Mourn. Linn. Soc. Bot.' vol. translation of the first edition of 

viii. 1804, p. 130. Bronn has tliiis work. 

described the structure of Stan- f 'Bot. Zeitung,' 18G8, p. 630. 
hopea devoniemis, in his German 



172 VANDE^. Chap. VI. 

into it only with extreme difficulty. In the case of 
Cirrhaea, he found that this could be effected more 
easily, after they had shrunk a little from being left 
to dry for half an hour or an hour. He observed two 
flowers with pollen-masses naturally inserted by some 
means into their stigmas. On several occasions aftei 
forcing the end of a pollen-mass into the mouth of the 
stigma, he witnessed a most curious process of deglu- 
tition. The extremity of the pollen-mass swells from 
imbibing moisture, and as the chamber gradually 
widens downwards, the swelling part is forced down- 
wards ; so that the whole is at last drawn inwards and 
disappears. In the case of Notylia, Fritz Miiller ob- 
served that the entrance into the stigma became a 
little larger after the flower had remained expanded 
for about a week. In whatever manner this latter 
plant is fertilised, it is certain that it must be im- 
pregnated with pollen from a distinct plant ; as it 
offers one of those extraordinary cases in which its own 
pollen acts like poison on the stigma. 

In the last edition of this work it was shown that 
the ovaria of mature flowers of Acropera do not con- 
tain any ovules. But I erred greatly in the interpre- 
tation of this fact, for I concluded that the sexes were 
separate. I was however soon convinced of my error 
by Mr. Scott, who succeeded in artificially fertilising 
the flowers with their own pollen. A remarkable dis- 
covery by Hildebrand, * namely, that in many Orchids 
the ovules are not developed unless the stigma is 
penetrated by the pollen-tubes, and that their develop- 
ment occurs only after an interval of several weeks 
or even months, explains the state of the ovarium 
in Acropera, as observed by me. According also to 



♦ 'Bot. Zeitung,' 18G3, Oct. 30, et seq, and Aug. 4, 1865. 



CiiAP VI. COEYANTIIES. 173 

Fritz Miiller, * the ovules of many endemic Epidendrese 
and Vandeae in Brazil remain in a very imperfect state 
of development for some months, and even in one case 
for half a year, after the flowers had been fertilised. 
He suggests that a plant which produces hundreds of 
thousands of ovules, would waste much power if these 
were formed and did not happen to be fertilised, and 
we know that fertilisation is a doubtful and difficult 
operation with many Orchids. It would therefore be 
an advantage to such plants, if the ovules were not at 
all developed until their fertilisation was assured by 
the pollen- tubes having already penetrated the stigma. 

Coryantlies. — I will conclude this chapter by giving 
an account of the fertilisation of the flowers of Cory- 
anthes, which is effected in a manner that might perhaps 
have been inferred from their structure, but would have 
appeared utterly incredible had it not been repeatedly 
witnessed by a careful observer, namely, the late Dr. 
Criiger, Director of the Botanical Gardens at Trinidad. 
The flowers are very large and hang downwards. The 
distal portion of the labellum (L) in the following wood- 
cut, fig. 27, is converted into a large bucket (B). Two 
appendages (H), arising from the narrowed base of the 
labellum, stand directly over the bucket and secrete so 
much fluid that drops may be seen falling into it. 
This fluid is limpid and so slightly sweet that it does 
not deserve to be called nectar, though evidently of the 
same nature ; nor does it serve to attract insects. M. 
Meniere estimates that the total quantity secreted by 
a single flower is about an English ounce, t AVhcn 
the bucket is full the fluid overflows by the spout (P). 



» 'Bot. Zeitiing,' 1868, p. 1G4. 

t * Bulletin (ie la Soo. Bot. dc Frauoe,' torn. ii. 1855, p. 351. 



171 



VANDE^. 



Chap VL 



Fig. 27. 




CORYANTilES SPECIOSA. (Copied from Lindley's ' Vegetable Kingdon).') 



L. labellnm. 

B. bucket of the labellum. 

H. fluid-secreting appendages. 



P. spout of bucket, orer-archeJ br 
the end of the column, bearing 
the anther and stigma. 



CUAP. VI. CORYANTHES. 175 

This spout is closely over-arched by the end of the 
column, which bears the stigma and pollen-masses in 
such a position, that an insect forcing its way out of 
the bucket through this passage would first brush with 
its back against the stigma and afterwards against the 
viscid discs of the pollinia, and thus remove them. 
We are now prepared to hear what Dr. Criiger says 
about the fertilisation of an allied species, the G. 
macrantha, the labellum of which is provided with 
crests.* I may premise that he sent me specimens of 
the bees which he saw gnawing these crests, and they 
belong, as I am informed by Mr. F. Smith, to the genus 
Euglossa. Dr. Criiger states that these bees may be 
" seen in great numbers disputing with each other for 
a place on the edge of the hypochil (i. e. the basal part 
of the labellum). Partly by this contest, partly perhaps 
intoxicated by the matter they are indulging in, they 
tumble down into the * bucket,* half-full of a fluid 
secreted by organs situated at the base of the column. 
They then crawl along in the water towards the 
anterior side of the bucket, where there is a passage 
for them between the opening of this and the column. 
If one is early on the look-out, as these Hymenopterse 
are early risers, one can see in every flower how 
tecundation is performed. The humble-bee, in forcing 
its way out of its involuntary bath, has to exert itself 
considerably, as the mouth of the epichil (i. e. the 
distal part of the labellum) and the face of the column 
fit together exactly, and are very stiff and elastic. The 
first bee, then, which is immersed will have the gland 



* ' Joainal of Linn. Sne. Bot.* drawing of G.feildlngii in ' Jour- 

vol. viii. 18()4, p. 130. There is nal of Hort. 8oc.' vol. iii, p. 10. 

a drawinnj of this species in Pax- I am indebted to Mr. Thiselton 

toil's ' Mas;, of Botany,' vol. v. p. Dyer for informing me of these 

;H1, but it is too complicated to be figurce. 
reproduced. There is also a 



176 VANDEiE. Chap. VI 

of the pollen -mass glued to its back. The insect then 
generally gets through the passage, and comes out 
with this peculiar appendage, to return nearly imme- 
diately to its feast, when it is generally precipitated a 
second time into the bucket, passing out through the 
same opening, and so inserting the pollen-masses into 
the stigma while it forces its way out, and thereby im- 
pregnating either the same or some other flower. I 
have often seen this ; and sometimes there are so many 
of these humble-bees assembled that there is a continual 
procession of them through the passage specified." 

There cannot be the least doubt that the fertilisation 
of the flower absolutely depends on insects crawling 
out through the passage formed by the extremity of 
the labellum and the over-arching column. If the 
large distal portion of the labellum or bucket had been 
dry, the bees could easily have escaped by flying away. 
Therefore we must believe that the fluid is secreted by 
the appendages in such extraordinary quantity and is 
collected in the bucket, not as a palatable attraction 
for the bees, as these are known to gnaw the labellum, 
but for the sake of wetting their wings, and thus 
compelling them to crawl out through the passage. 

I have now described, perhaps in too much detail, 
a few of the many contrivances by which the VandesR 
are fertilised. The relative position and shape of the 
parts — friction, viscidity, elastic and hygrometric move- 
ments, all nicely related to one another — come into 
play. But all these appliances are subordinate to the 
aid of insects. Without their aid, not a plant belong- 
ing to this tribe, in the species of the twenty-nine 
genera examined by me, would set a seed. It is also 
certain in a majority of the cases, that insects withdraw 
the pollinia only when retreating from the flower, and 



UEAP. VI CORYANTHES. 177 

by carrying them away, effect a union between two 
flowers, generally on distinct plants. This can hardly 
fail to occur in all the many cases in which the pollinia 
slowly change their position, when removed from the 
rostellum, in order to assume a proper direction for 
striking the stigma ; for the insects during this in- 
terval will have had time to fly from the flowers on 
cne plant which will serve as the male, to those 
an another plant which will serve as the female. 



178 VANDEJE. Chaf. YO. 



CHAPTEE Til. 

VANDEJi: continued. — catasetid^e 

OatasetidsB, the most remarkable of all Orchids— The mechanism by 
which the pollinia of Catasetum are ejected to a distance and art, 
transported by insects— Sensitiveness of the horns of the rostellura 
— Extraordinary diiference in the male, female, and hermaphrodite 
forms of Catasetum tridentatum—Mormodesigiiea, curious structure 
of the flowers ; ejection of the pollinia— Mor modes luxata— Cyc- 
noches ventricosum, manner of fertilisation. 

1 HAVE reserved for separate description one sub-famil> 
of the Vande^, namely, the Catasetidae, which must, I 
think, be considered as the most remarkable of all 
Orchids. 

I will begin with Catasetum. A brief inspection of 
the flower shows that here, as with most other Orchids, 
some mechanical aid is requisite to remove the pollen- 
masses from their cells, and to carry them to the 
stigmatic surface. We shall, moreover, presently see 
that Catasetum is exclusively a male form ; so that 
the pollen-masses must be transported to the female 
plant, in order that seed should be produced. The 
pollinium is furnished with a viscid disc of huge size ; 
but this, instead of being placed in a position likely 
to touch and adhere to an insect visiting the flower, is 
turned inwards and lies close to the upper and back 
surface of a chamber, which must be called the stig- 
matic chamber, though functionless as a stigma. There 
is nothing in this chamber to attract insects ; and even 
if they did enter it. the viscid surface of the disc could 
not possibly come into contact with them. ♦ 



Chap. Vll. CATASETUM. 179 

How then does Nature act ? She has endowed these 
plants with, what must be called for want of a better 
term, sensitiveness, and with the remarkable power of 
forcibly ejecting their pollinia even to a considerable 
distance. Hence, when certain definite points of the 
flower are touched by an insect, the pollinia are shot 
forth like an arrow, not barbed however, but having 
a blunt and excessively adhesive point. The insect, 
disturbed by so sharp a blow, or after having eaten its 
fill, flies sooner or later away to a female plant, and, 
whilst standing in the same position as before, the 
pollen-bearing end of the arrow is inserted into the 
stigmatic cavity, and a mass of pollen is left on its 
viscid surface. Thus, and thus alone, can the five 
species of Catasetum which I have examined be 
fertilised. 

In many Orchideae, as in Listera, Spiranthes, and 
Orchis, the surface of the rostellum is so far sensitive, 
that, when touched or when exposed to the vapour of 
chloroform, it ruptures in certain defined lines. So it 
is in the tribe of the Catasetidee, but with this re- 
markable difference, that in Catasetum the rostellum is 
prolonged into two curved tapering horns, or, as I shall 
call them, antennae, which stand over the labellum 
where insects alight. If these are touched even very 
lightly, they convey some stimulus to the membrane 
which surrounds and connects the disc of the pol- 
linium with the adjoining surface, causing it instantly 
to rupture; and as soon as this happens the disc is 
suddenly set free. We have also seen in several 
Vandeae that the pedicels of the pollinia are fastened 
flat down in a state of tension, and are highly elastic, 
so that, when freed, they immediately spring up, appa- 
rently for the sake of detaching the pollen-masses from 
the anther-cells. In the genus Catasetum, on the 



180 VANDEJi. Chap. VI t. 

other liand, the pedicels are fastened down in a curved 
position ; and when freed by the rupture of the attached 
edges of the disc, they straighten themselves with such 
force, that not only do they drag the balls of pollen 
together wdth the anther-cells from their places of 
attachment, but the whole poUinium is jerked forward, 
over and beyond the tips of the so-called antennae, to 
the distance sometimes of two or three feet. Thus, 
as throughout nature, pre-existing structures and capa- 
cities are utilised for new purposes. 

Catasetum saccatum.^ — I will first describe the male 
forms, belonging to five species, which are included 
under the generic name of Catasetum. The general 
appearance of the present species is represented in the 
following woodcut, fig. 28. A side view of the flower, 
with all the petals and sepals excepting the labellum 
cut off, is shown by B ; and A gives a front view of 
the column. The upper sepal and two upper petals 
surround and protect the column ; the two lower sepals 
project out at right angles. The flower stands more 
or less inclined to either side, but with the labellum 
downwards, as represented in the drawing. The dull 
coppery and orange-spotted tints, — the yawning cavity 
in the great fringed labellum, — the one antenna 
projecting with the other hanging down — give to 
these flow^ers a strange, lurid, and almost reptilian 
appearance. 

In front of the column, in the middle, the deep 
stigmatic chamber (fig. 28, A, s), may be seen ; but this 
is best shown in the section (fig. 29, C, s), in which all 



* I am m\\f\). indel^ted to Mr. mngnificent collection of Orchids, 

James Veitch of Chelsta for the generously sent me two fine spikes, 

first specimen which I saw of and has aided me in the kindest 

this Orchid ; f-ub^-equently Mr. manner with other specimens. 
S. Kucker, so well known for his 



Chap. VII. CATASETUM SACCATUM. 181 

the parts are a little separated from each other, in 
order that the mechanism may be intelligible. In 
the middle of the roof of the stigmatic chamber, far 
back (fZ, in A, fig. 28), the upturned anterior edge of 
the viscid disc can just be seen. The upper mem- 
branous surface of the disc, before it is ruptured, is 
continuous with the fringed bases of the two antennce 
between which it lies. The rostellum projects over 
the disc and stigmatic chamber (see section C, fig. 29), 
and is prolonged on each side so as to form the two 
antenna3 ; the middle part is covered by the ribbon- 
like pedicel (jped.) of the pollinium. The lower end of 
the pedicel is attached to the disc, and the upper end 
to the two pollen-masses (jp) within the anther-cell. 
The pedicel in its natural position is held much 
bowed round the protuberant rostellum ; when freed 
it forcibly straightens itself, and at the same time its 
lateral edges curl inwards. At an early period of 
growth, it is continuous with the rostellum, but sub- 
sequently becomes separated from it by the solution 
of a layer of cells. 

The pollinium when set free and after it has 
straightened itself, is represented at D, fig. 29. Its 
under surface, which lies in contact with the rostellum, 
is shown at E, with the lateral edges of the pedicel 
now curled inwards. In this latter view, the clefts in 
the under sides of the two pollen-masses are shown. 
Within these clefts, near their bases, a layer of strong 
extensible tissue is attached, forming the caudicles, by 
which the pollen-masses are united to the pedicel. 
The lower end of the pedicel is joined to the disc by a 
flexible hinge, which occurs in no other genus, so that 
the pedicel can play backwards and forwards, as far as 
the upturned end (fig. D) of the disc permits. The 
disc is large and thick ; it consists of a strong upper 



182 



VANDE.E. 



Chap. VH. 



Fis. 28. 




Catasetum saccatum 



CuAP. Vn. CATASETUM SACCATUM. 



183 



Fig. 29. 






LATASETUM SACCATUM. 



a. anther. 

an antennae of the rostellum. 

d. disc of polliniuin. 

/. filament of anther. 

g. germen or ovarium. 

I. labelium. 

p. pollen-masses. 

pd or ped. pedicel of pollinium. 

j>. stigmatic chamber. 

A. Front view of column. 



B. Side view of flower, with all tlie 

sepals and petals removed ex- 
cept the labelium. 

C. Diagrammatic section through 

the column, with all the parts 
a little separated. 

D. Pollinium, upper surface. 

E. Pollinium, lower surface, which 

before removal lies in close 
contact with the rostellum. 



184 VANDE^. Chap. VII. 

membrane; to which the pedicel is united, with an 
inferior cushion of great thickness, of pulpy, flocculent, 
and viscid matter. The posterior margin is much the 
most viscid part, and this necessarily first strikes any 
object when the pollinium is ejected. The viscid 
matter soon sets hard. The whole surface of the disc 
is kept damp before ejection, by resting close against 
the roof of the stigmatic chamber ; but in the section 
(fig. C) it is represented, like the other parts, a little 
separated from the roof. 

The connective membrane of the anther {a in all the 
figures) is produced into a spike, which adheres loosely 
to the pointed end of the column ; this pointed end 
(/, fig. C) is homologically the filament of the anther. 

The anther has this peculiar shape apparently for 
the sake of leverage, so that it may be easily torn off 
by a pull at its lower end, when the pollinium is 
jerked out by the elasticity of the pedicel. 

The labellum stands at right angles to the column, 
or hangs a little downwards ; its lateral and basal 
lobes are turned under the middle portion, so that an 
insect can stand only in front of the column. In the 
middle of the labellum there is a deep cavity, bordered 
by crests. This cavity does not secrete nectar, but its 
walls are thick and fleshy, with a slightly sweet nutri- 
tious taste ; and it will presently be shown that they 
are gnawed by insects. The extremity of the left- 
hand antenna stands immediately over the cavity, and 
would infalliby be touched by an insect visiting this 
part of the labellum for any purpose. 

The antennae are the most singular organs of the 
flower, and occur in no other genus. They form rigid, 
curved horns, tapering to a point. They consist of a 
narrow ribbon of membrane, with the edges curled in* 
wards so as to touch ; each horn therefore is tubular, 



Chap. VII. CATASETUM SACCATUM. 185 

with a slit down one side, like an adder's fang. They 
are composed of numerous, much elongated, generally 
hexagonal cells, pointed at both ends ; and these cells 
(like those in most of the other tissues of the flower) 
have nuclei with nucleoli. The antennae are prolonga- 
tions of the sides of the anterior face of the rostellum. 
As the viscid disc is continuous with a little fringe of 
membrane on each side, and as this fringe is continuous 
with the bases of the antennae, these latter organs are 
put into direct connection with the disc. The pedicel 
of the pollinium passes, as already stated, between the 
bases of the two antennae. The antennae are not free 
for their whole length ; but their exterior edges are 
firmly united to and blend for a considerable space 
with the margins of the stigmatic chamber. 

In all the flowers which I examined, taken from 
three plants, the two antennae which are alike in 
structure occupied the same relative position. The 
extreme part of the left-hand antenna bends upwards 
(see B, fig. 28, in which the position is shown plainer 
than in A), and at the same time a little inwards, so 
that its tip is medial and guards the entrance into 
the cavity of the labellum. The right-hand antenna 
hangs down, with its tip turned a little outwards ; and 
as we shall immediately see, is almost paralysed, so as 
to be functionless. 

Now for the action of the parts. When the left- 
hand antenna of this species (or either of the antennae 
in three of the following species) is touched, the edges 
of the upper membrane of the disc, which are con- 
tinuously united with the surrounding surface, instantly 
rupture, and the disc is set free. The highly elastic 
pedicel then instantly flirts the heavy disc out of the 
stigmatic chamber with such force, that the whole 
pollinium is ejected, bringing away with it the two 



186 VANDEJ5. Chap. VU. 

balls of pollen, and tearing tlie loosely attached spike- 
like anther from the top of the column. The pollinium 
is always ejected with its viscid disc foremost. I 
imitated the action with a minnte strip of Avhalebone, 
slightly weighted at one end to represent the disc; 
this was then bent half round a cylindrical object, 
the upper end being at the same time gently held by 
the smooth head of a pin, to represent the retarding 
action of the anther, the lower end was then suddenly 
set free, and the whalebone was pitched forward, like 
the pollinium of the Catasetum, with the weighted 
end foremost. 

That the disc is first jerked out of the stigmatic 
chamber, I ascertained by pressing the middle of the 
pedicel ; and when I touched the antenna the disc 
instantly sprung forth, but, owing to the pressure on 
the pedicel, the pollinium was not dragged out of the 
anther-cell. Besides the spring from the straighten- 
ing of the pedicel, elasticity in a transverse direction 
comes into play : if a quill be split lengthways, and 
the half be forced longitudinally on a too thick pencil, 
immediately the pressure is removed the quill jumps 
off; and an analogous action takes place with the 
pedicel of the pollinium, owing to the sudden inward 
curling of its edges, when set free. These combined 
forces suffice to eject the pollinium with considerable 
force to the distance of two or three feet. Several 
persons have told me that, when touching the flowers 
of this genus in their hothouses, the pollinia have 
.struck their faces. I touched the antennsB of C. cal- 
losum whilst holding the flower at about a yard's 
distance from a window, and the pollinium hit the 
pane of glass, and stuck by its adhesive disc, to the 
smooth vertical surface. 

The following observations on the nature of the 



Chap. VII. CATASETUM. 187 

excitement wliich causes the disc to separate from the 
surrounding parts, include some made on the following 
species. Several flowers were sent me by post and by 
the railroad, and must have been much jarred, but 
they had not exploded. I let two flowers fall from a 
height of two or three inches on the table, but the 
poUinia were not ejected. I cut off with a crash with 
a pair of scissors the thick labellum and ovarium 
close beneath the flower ; but this violence produced 
no effect. Nor did deep pricks in various parts of the 
column, even within the stigmatic chamber. A blow, 
sufficiently hard to knock off the anther, causes the 
ejection of the pollinium, as occurred to me once 
by accident. Twice I pressed rather hard on the 
pedicel, and consequently on the underlying ■ ros- 
tellum, without any effect. Whilst pressing on the 
pedicel, I gently removed the anther, and then the 
pollen-bearing end of the pollinium sprang up from 
its elasticity, and this movement caused the disc to 
separate. M. Meniere,* however, states that the 
anther-case sometimes detaches itself, or can be gently 
detached, without the disc separating ; and that then 
the upper end of the pedicel, bearing the pollen-masses, 
swings downwards in front of the stigmatic chamber. 

After trials made on fifteen flowers of three species, 
I find that no moderate degree of violence on any 
part of the flower, except on the antennae, produces 
any effect. But when the left-hand antenna of G. 
saccatum, or either antenna of the three following 
species, is touched, the pollinium is instantly ejected. 
The extreme tip and the whole length of the antennae 
are sensitive. In one specimen of G. tridentatum a 
touch from a bristle sufficed ; in five specimens of 



* ' Bull, (le la Soc. Bot. de France,' torn. i. 1854, p. 367. 



188 VANDE^. Chap. VII 

(7. saccafum a gentle touch from a fine needle was 
necessary ; but in four other specimens a slight blow 
was requisite. In G. tridentatum a stream of air and 
of cold water from a small pipe did not suffice ; nor 
in any case did a touch from a human hair ; so that 
the antennae are less sensitive than the rostellum of 
Listera. Such extreme sensitiveness would indeed 
have been useless to the plant, for, as is now known, 
the flowers are visited by powerful insects. 

That the disc does not separate owing to the simple 
mechanical movement of the antennae is certain; for 
they adhere firmly for a considerable space to the 
sides of the stigmatic chamber, and are thus im- 
movably fixed near their bases. If a vibration is 
conveyed along them, it must be of some special 
nature, for ordinary jars of manifold greater strength 
do not excite the act of rupture. The flowers in some 
cases, when they first arrived, were not sensitive, but 
after the cut-off spikes had stood for a day or two in 
water they became sensitive. Whether this was owing 
to fuller maturity or to the absorption of water, I know 
not. Two flowers of C. caUosum, which were completely 
torpid, were immersed in tepid water for an hour ; 
and then the antennae became highly sensitive ; this 
indicates either that the cellular tissue of the antennae 
must be turgid in order to receive and convey the 
effects of a touch, or, as is more probable, heat in- 
creases their sensitiveness. Two other flowers placed 
in hot water, but not so hot as to scald my fingers, 
spontaneously ejected their pollinia. A plant of C. 
tridentatum had been kept for some days in a rather 
cool house, and tiie antennae were consequently in a 
torpid condition ; f. flower was cut off and placed in 
water at a temperature of 100'' F. (37-7° C), and no 
effect w*:s immsd lately produced ; but when it was 



Chap. VII. CATASETUM. 189 

looked at after an interval of 1^ 30™ tlie pollinium was 
found ejected. Another flower was placed in water at 
90" F. (32-2" C), and after 25™- the pollininm was found 
ejected : two other flowers left for 20™- in water at 
87° F. (30*5° C.) did not explode, though they were after- 
wards proved to be sensitive to a slight touch. Lastly, 
four flowers were placed in water at 83° F. (28-3° C.j ; 
two of these did not eject their pollinia in 45™, and 
were then found to be sensitive ; whereas the other two, 
when looked at after 1^ 15™-, had spontaneously ejected 
their pollinia. These cases show that immersion in 
water raised to a temperature only a little higher than 
that to which the plant had been exposed, causes the 
membrane by which the discs are attached to rupture. 
A thin stream of almost boiling water was allowed to 
fall through a fine pipe on the antenna3 of some flowers 
on the above plant ; these were softened and killed 
but the pollinia were not ejected. Nor did sulphuric 
acid, dropped on the tips of the antennae, cause any 
action ; though their upper parts which had not 
been injured by the acid were afterwards found to bo 
sensitive to a touch. In these two latter cases, I 
presume that the shock was so sudden and violent 
that the tissue was instantly killed. Considering 
the above several facts, we may infer that it must 
be some molecular change which is conveyed along 
the antennae, causing the membrane round the discs to 
rupture. In G, tridentatum the antenna? were one inch 
and a tenth in length, and a gentle touch from a bristle 
on the extreme tip was conveyed, as far as I could 
perceive, instantaneously throughout this length. I 
measured several cells in the tissue composing the 
antennae of this species, and on a rough average it 
appeared that the stimulus must travel through no less 
than from seventy to eighty cells. 



190 VANDE^. Chap. VII. 

We may, at least, safely conclude that the antennge, 
which are characteristic of the genus Catasetum, are 
specially adapted to receive and convey the effects of 
a touch to the disc of the pollinium. This causes the 
membrane to rupture, and the pollinium is then ejected 
by the elasticity of its pedicel. If we required further 
proof, nature affords it in the case of the so-called 
genus Monachanthus, which, as we shall presently see^ 
is the female of Catasetum tridentatum, and it does not 
possess pollinia which can be ejected, and the antennae 
are here entirely absent. 

I have stated that in C. saccatiim the right-hand 
antenna invariably hangs down, with the tip turned 
slightly outwards, and that it is almost paralysed. I 
ground my belief on five trials, in which I violently 
hit, bent, and pricked this antenna, and this produced 
no effect ; but when immediately afterwards the left- 
hand antenna was touched with much less force, the 
pollinium was shot forth. In a sixth case a forcible 
blow on the right-hand antenna did cause the act of 
ejection, so that it is not completely paralysed. As 
this antenna does not guard the labellum, which in all 
Orchids is the part attractive, that is to insects, its 
sensitiveness would be useless. 

From the large size of the flower, more especially 
of the viscid disc, and from its wonderful power of 
adhesion, I formerly inferred that the flowers were 
visited by large insects, and this is now known to be 
the case. The viscid matter sticks so firmly after it 
has set hard, and the pedicel is so strong (though very 
thin and only one-twentieth of an inch in breadth at 
the hinge), that to my surprise a pollinium attached 
to an object supported for a few seconds a weight of 
1262 grains, or nearly three ounces ; and it supported 
for a considerable time a slightly less weight. When 



Chap. VII. 



CATASETUM. 



191 



the pollinium is shot forth, the large spike-like anther 
is generally carried with it. If the disc strikes a flat 
surface like a table, the momentum from the weight 
of the anther often carries the pollen-bearing end 
beyond the disc, and the pollinium is thus affixed in 
a wrong direction for the fertilisation of another 
flower, supposing it to have been attached to an 
insect's body. The flight of the pollinium is often 
rather crooked. * But it must not be forgotten that 
under nature the ejection is caused by the antennae 
being touched by a large insect standing on the la- 
bellum, which will thus have its head and thorax 
placed near to the anther. A rounded object thus 
held is always accurately struck in the middle, and 
when removed with the pollinium adhering to it, the 
weight of the anther depresses the hinge of the pol- 
linium ; and in this position the anther-case readily 
drops off, leaving the balls of pollen free, in a proper 
position for fertilising the female flower. The utility 



* M. Baillon (• Bull, de la Soc. 
Bot. de France,' torn. i. 1854, p. 
285) states that Gatasetum luridum 
ejects its pollinia always in a 
straight line, and in such a direc- 
tion that it sticks fast to the 
bottom of the concavity of the 
labellum ; and he imagines that 
in this position it fertilises the 
flower in a manner not clearly 
explained. In a subsequent paper 
in the same volume (p. 367) M. 
Me'niere justly disputes M. Bail- 
Ion's conclusion. He remarks 
that the anther-case is easily de- 
tached, and sometimes naturally 
detaches itself ; the pollinia then 
swing downwards by the elasticity 
of the pedicel, the viscid disc still 
remaining: attached to the roof 
of the stigmatic chamber. M. 
Meniere hints that, by the subse- 



quent and progressive retraction 
of the pedicel, the pollen-masses 
might be carried into the st'gmatic 
chamber. This is not possible in 
the three species which I have 
examined, and would be uselej^s. 
But M. Meniere himself then goes 
on to show how important insects 
are fur the fertilisation of Orchids ; 
and apparently infers that their 
agency comes into play with 
Catasetum, and that this plant 
does not fertilise itself. Both INI. 
Baillon and M. Me'niere correctly 
describe the curved position in 
wliicli the elastic pedicel lies 
before it is set fiee. Neither of 
these botani.-ts seenis to be aware 
that the species of Catasetijin 
(at lea^t the five which I have 
examined; are exclusively mole 
plants. 



192 VANDE^. Chap. VIL 

of so forcible an ejection no doubt is to drive the soft 
and viscid cushion of the disc against the hairy thorax 
of the large hymenopterous insects which frequent the 
flowers. When once attached to an insect, assuredly 
no force which the insect could exert would remove 
the disc and pedicel ; but the caudicles are ruptured 
without much difficulty, and thus the balls of pollen 
might readily be left on the adhesive stigma of tlie 
female flower. 

Gatasetum callosum. — The flowers of this species * are 
smaller than those of the last, but resemble them in 
most respects. The edge of the labellum is covered 
with papillae ; the cavity in the middle is small, and 
behind it there is an elongated anvil-like projection, 
— facts which I mention from the resemblance in some 
of these points between the labellum of this species 
and that of Myanthus harhatus, the hermaphrodite form 
of Gatasetum tridentatum, presently to be described. 
When either antenna is touched, the pollinium is 
ejected with much force. The yellow-coloured pedicel 
is much bowed, and is joined by a hinge to the ex- 
tremely viscid disc. The two antennae stand sym- 
metrically on each side of the anvil-like projection, 
with their tips lying within the small cavity of the 
labellum. The walls of this cavity have a pleasant 
nutritious taste. The antennae are remarkable, from 
their whole surface being roughened with papillae. 
The plant is a male, and the female form is at present 
unknown. 

Gatasetum tabular e. — This species belongs to the 
same type as G. saceatum, but differs greatly from it in 
appearance. The central portion^ of the labellum con- 
sists of a narrow, elongated, table-like projection, of 

* A fine sp'ke of flowers of this Mr. Kucker, and was named for 
species was kindly sent me by me by Dr. Lindloy. 



Chap. YII. CATASETUM TEIUENTATUM. 193 

an almost white colour and formed of a thick mass 
of succulent tissue, havino^ a sweetish taste. Towards 
the base of the labellum there is a large cavity, which 
externally resembles the nectary of an ordinary flower, 
but apparently never contains nectar. The pointed 
extremity of the left-hand antenna lies within this 
cavity, and would infallibly be touched by an insect 
gnawing the bilobed and basal end of the medial pro- 
jection of the labellum. The right-hand antenna is 
turned inwards, with the extreme part bent at right 
angles and pressed against the column; therefore I 
do not doubt that it is paralysed as in G. saceatum ; 
but the flowers examined by me had lost almost all 
their sensitiveness. 

Catasetum planiceps {?). — This species does not differ 
much from the following one, so I will describe it 
briefly. The green and spotted labellum stands on 
the upper side of the flower ; it is jar-shaped, with 
a small orifice. The two elongated and roughened 
antennae lie coiled up some little way apart and 
parallel to one another, within the labellum. They 
are both sensitive to a touch. 

Catasetum tridentatum. — The general appearance 
of this species, which is very different from that of 
G. saceatum, callosum and tabular e, is represented in 
fig. 30, with a sepal on each side cut off. 

The flower stands with the labellum uppermost, that 
is, in a reversed position compared with most Orchids. 
The labellum is helmet-shaped, its distal portion being 
reduced to three small points. It cannot hold nectar 
from its position ; but the walls are thick, and have, as 
in the other species, a pleasant nutritious taste. The 
stigmatic chamber, though functionless as a stigma, 
is of large size. The summit of the column, and the 
spike-like anther, are not so much elongated as in 



194 



MONACHANTHUS VIRIDIS. 



Chap. Vll. 



C. saccatwn. In other respects there is no important 
difference. The antennae are of greater length ; their 
tips for about one-twentieth of their length are 
roughened by cells produced into papillae. 

Fig. 30. 




Catasetum tridentatum. 



a. anther. 

pd. pedicel of pollinium. 

an. antennce, 

I. labellum. 



A. Side view of flower in its natural 

position, with two of the sepals 
cut off. 

B. Front view of column, in position 

reverse of ti^r. A. 



The pedicel of the pollinium is articulated as before 
by a hinge to the disc ; it can move freely only in one 
direction owing to one end of the disc being upturned, 
and this restricted power of movement apparently 
comes into play when the pollinium is carried by an 
insect to the female flower. The disc is, as in the other 
species, of large size, and the end which when ejected 
first strikes any object, is much more viscid than the 
rest of the surface. This latter surface is drenched 
with a milky fluid, which, when exposed to the air, 
rapidly turns bro^\^l, and sets into a cheesy consistence. 
The upper surface of the disc consists of strong mem* 



Chap. YJl. CATASETUM TllIDENTATUM. 195 

brane formed of polygonal cells, resting on and adhering 
to a thick cushion, formed of irregular rounded balls 
of brown matter, separated from each other and em- 
bedded in a transparent, structureless, highly elastic 
substance. This cushion towards the posterior end of 
the disc graduates into viscid matter, which when 
consolidated is brown, translucent, and homogeneous. 
Altogether the disc of Catasetum presents a much 
more complex structure than in the other Yandese. 

I need not further describe the present species, 
except as to the position of the antennae. They oc- 
cupied exactly the same position in all the many 
flowers which were examined. Both lie curled within 
the helmet-like labellum ; the left-hand one stands 
higher up, with its inwardly bowed extremity in the 
middle ; the right-hand antenna lies lower down and 
crosses the whole base of the labellum, with the tip 
just projecting beyond the left margin of the base of 
the column. Both are sensitive, but apparently the 
one which is coiled within the middle of the labellum 
is the more sensitive of the two. From the position 
of the petals and sepals, an insect visiting the flower 
would almost certainly alight on the crest of the la- 
bellum; and it could hardly gnaw any part of the 
great cavity without touching one of the two antennae, 
for the left-hand one guards the upper part, and the 
right-hand one the lower part. When either of these 
is touched the pollinium is ejected and the disc will 
strike the head or thorax of the insect. 

The position of the antennae in this Catasetum may 
be compared with that of a man with his left arm raised 
and bent so that his hand stands in front of his chest, 
and with his right arm crossing his body lower down 
so that the fingers project just beyond his left side. 
In Catasetum callosim both arms are hekl lower down 



196 VANDE.E. Chap. VIL 

and are extended symmetrically. In C. saccatum the 
left arm is bowed and held in front, as in C. triden- 
tat urn, but rather lower down ; whilst the right arm 
hangs downwards paralysed, with the hand turned a 
little outwards. In every case notice w411 be given in 
an admirable manner, when an insect visits the label- 
lum, and the time has arrived for the ejection of the 
pollinium, so that it may be transported to the female 
plant. 

Gatasetmn tridentatum is interesting under another 
point of view. Botanists were astonished when Sir R. 
Schomburgk* stated that he had seen three forms, 
believed to constitute three distinct genera, namely, 
Catasetum tridentatum, Monachanthus viridis, and 
Mijantlius harbatus, all growing on the same plant. 
Lindley remarked t that " such cases shake to the 
foundation all our ideas of the stability of genera and 
species." Sir R. Schomburgk affirms that he has seen 
hundreds of plants of G. tridentatum in Essequibo with- 
out ever finding one specimen with seeds ;{ whereas 

* 'Transaciions of tlioLinntan Bristol. Lastly Dean Herbert 

See' vol. xvii. p. 522. Another infonned me many years n go that 

account by Dr. Lindley appeared Cataseium luridum flowered »nd 

in the 'Lutanicul Kegister,' fol. kept true for nine years in the 

1951, of a distinct species of My- Botanic Garden at York ; it then 

anthus and Monachantlius appear- threw up a scape of a Myanthus, 

ing on the same scape : he alludes which as we shall pr< seutly see is 

also to other cases. Some of the an hermaphrodite, intermediate in 

dowers in these cases were in an in- form between tlie male and f«-male. 

termediate condition, which is not ]M. Duchartro has given a full his- 

snrprising, i^eting that in dioecious tori' al at-couot of the appearance 

plants we some tim«siiave a pirtial of tliese forms on the same plant, 

resumption of the characters of in ' Bull, de la Soc. Bot. de 

both sexes. Mr. IL dgers of River- France,' vol ix. 1862, p. US. 

hill informs me ti. at he iinportid t The ^' Vegetable Kingdom,* 

from De erara a Myanthus, and 1S53, p. 178. 

ti.ai v\h n it tlowered a second % Bmngniart states ('Bull, de 

t,i...e it was inetamorphosed into la Soc. B-t. de France,' toiu. ii. 

a Ci.ta^elum. Dr. Carpenter ]8.'i5, p. 20) that M. Neumann, a 

('Compan.tive Physiology,' 4th gi^ilful fertiliser of Orchids, could 

e<iit. p. tiyS) alludes to an ana- never succeed in fertilising Cata- 

logons case which occurred at setum. 



OuAP. VII. CATASETUM TRIDENTATUM. 197 

he was surprised at the gigantic seed-vessels of the 
Monachanthus ; and he correctly remarks that " here 
we have traces of sexual difference in Orchideous 
flowers." Dr. Crusher also informs me that in Trinidad 
he never saw capsules naturally produced by the 
flowers of this Catasetum ; * nor when they were fer- 
tilised by him with their own pollen, as was done 
repeatedly. On the other hand, when he fertilised 
the flowers of the Monaclianihus viridis with pollen 
from the Catasetum, the operation never failed. The 
Monachanthus also commonly produces fruit in a state 
of nature. 

From what I had myself observed, I was led to 
examine carefully the female organs of C. tridentatum, 
coMosum, and saccatum. In no case was the stigmatic 
surface viscid, as it is in all other Orchids (except as 
we shall hereafter see in Cypripedium), and as is 
indispensable for securing the pollen-masses by the 
rupture of the caudicles. I carefully looked to this 
point both in young and old flowers of G. tridentatum. 
When the surface of the stigmatic chamber and of the 
stigmatic canal of the above-named three species is 
scraped off, after having been kept in spirits, it is found 
to be composed of utriculi (including nuclei of the 
proper shape), but not nearly so numerous as with 
ordinary Orchids. The utriculi cohere more together 



* Dr. Hance writes to me thnt often occurred. J. G. Beer says 

he I as in his collection a plant of (quoted by Irmisch, • Beitrage zu 

Catasetum tridentatum from the Biolotjie der Orchideen,' 1853, p. 

West Indies bearing a tine capsule; 22) that during: three years he 

but it does not appear to have tried in vain to fertilise Catasetum, 

lieen ascertained that this par- but on one occasion, by placing 

ticulur flower was that of Cata- only the viscid disc of a pollinium 

8 turn, and there is no great im- within the stigma, a ripe fruit 

probability in a single flower of was produced ; but it may be 

Monachanthus being produced by asked, Did the seeds cuutain 

a plant of Catasetum. as well as a embryos? 
whole scape, which we know has 



198 VANDE.E. Chap. VU. 

and are more transparent ; T examined for comparison 
those of many kinds of Orchids which had been kept 
in spirits, and in all found them much less transparent. 
In G, tridentatunfiy the ovarium is shorter, much less 
deeply furrowed, narrower at the base, and internally 
more solid than in Monachanthus. Again, in all 
three species of Catasetum the ovule-bearing cords 
are short ; and the ovules present a considerably dif- 
ferent appearance, in being thinner, more transparent, 
and less pulpy than in the numerous other Orchids 
examined for the sake of comparison. Perhaps these 
bodies hardly ought to be called ovules, although they 
correspond closely in general appearance and position 
with true ovules, for I was unable in any case to make 
out the opening of the testa and the included nucleus ; 
nor were the ovules ever inverted. 

From these several facts, namely, — the shortness, 
smoothness, and narrowness of the ovarium, the short- 
ness of the ovule-bearing cords, the state of the ovules 
themselves, the stigmatic surface not being viscid, the 
transparent condition of the utriculi, — and from neither 
Sir R. Schomburgk nor Dr. Criiger having ever seen 
G. tridentahmi producing seed in its native home, 
or when artificially fertilised, we may confidently 
look at this species, as well as the other species of 
Catasetum, as male plants. 

With respect to Monachantlius viridis, and Myanthus 
barhatus, the President of the Linnean Society has 
kindly permitted me to examine the spike bearing 
these two so-called genera, preserved in spirits, which 
was sent home by Sir K. Schomburgk. The flower of 
the Monachanthus (A, fig. 31) resembles pretty closely 
in external appearance that of Gatasetum tridentatum 
(fig. 30). The labellum, which holds the same relative 
position to the other parts, is not nearly so deep, 



Chap. VII. 



CATASETUM TEIDENTATUM. 



190 



especially on the sides, and its edge is crenated. The 
other petals and sepals are all reflexed, and are not so 
much spotted as in the Catasetum. The bract at the 
base of the ovarium is much larger. The whole column, 

Fig. 81. 




B. Myanthus barbatus. 

a. anther. 

an. antennae. 

I. labellum. 

p. pollen-mass, rudimentary. 

s. stigmatic cleft. 

sep. two lower sepals. 



A. MONACIIANTIIUS VIRIDIS. 

A. Side view of Monachimthus viri- 

dis in its natural po.sition. (The 
shading in both drawings has 
been added from Mr. Reiss' 
drawing in the ' Linnean Trans- 
actions.') 

B. Side view of Myanthus harhatui 

in its natural position. 



especially the filament and the spike-like anther, are 
much shorter ; and the rostellum is much less protu- 
berant. The antennae are entirely absent, and the 
pollen-masses are rudimentary. These are interesting 



20C YANDEX. Chap. VII. 

facts, from corroborating the view taken of the function 
of the antennae ; for as there are no pollinia to eject, 
an organ adapted to convey the stimulus from the 
touch of an insect to the rostellum would be useless. 
I could find no trace of a viscid disc or pedicel, and 
no doubt they had been lost; for Dr. Criiger says* 
that " the anther of the female flower drops off imme- 
diately after the opening of the same, i. e. before the 
flower has reached perfection as regards colour, size, 
and smell. The disc does not cohere, or very slightly, 
to the pollen-masses, but drops off about the same 
time, with the anther ;" leaving behind them the rudi- 
mentary pollen-masses. 

Instead of a large stigmatic chamber, there is a 
narrow transverse cleft close beneath the small anther. 
I was able to insert one of the pollen-masses of the 
male Catasetum into this cleft, which from having been 
kept in spirits was lined with coagulated beads of 
viscid matter, and with utriculi. The utriculi, differ- 
ently from those in Catasetum, were charged (after 
having been kept in spirits) with brown matter. The 
ovarium is longer, thicker near the base, and more 
plainly furrowed than in Catasetum ; the ovule-bearing 
cords are also much longer, and the ovules more opaque 
and pulpy, as in all common Orchids. I believe that 
I saw the opening at the partially inverted end of the 
testa, with a large projecting nucleus ; but as the speci- 
mens had been kept many years in spirits and were 
somewhat altered, I dare not speak positively. From 
these facts alone it is almost certain that Monachanthus 
is a female plant; and as already stated, Sir R. 
Schomburgk and Dr. Criiger have both seen it seeding 
abundantly. Altogetlier the flower differs in a most 



* ' Journ. Linn. Soc. Bot' vol. viii. 1864, p. 127. 



Cbap. VI]. MONACHAilTHUS VIRIDIS. 201 

remarkable manner from that of the male Gatasetum 
tridentatum, and it is no wonder that the two plants 
were formerly ranked as distinct genera. 

The pollen-masses offer so cnrious and good an illus- 
tration of a structure in a rudimentary condition, that 
they are worth description ; but I must first recur to 
the perfect pollen-masses of the male Catasetum. 
These may be seen at D and E, fig. 29, attached to 
the pedicel : they consist of a large sheet of cemented 
or waxy pollen-grains, folded over so as to form a 
sack, with an open slit along the lower surface, within 
which at the lower and produced end, a layer of highly 
elastic tissue, forming the caudicle, is attached; the 
other end being attached to the pedicel of the rostellum. 
The exterior grains of pollen are more angular, have 
thicker walls, and are yellower than the interior grains. 
In the early bud the two pollen-masses are enveloped 
in two conjoined membranous sacks, which are soon 
penetrated by the two produced ends of the pollen- 
masses and by their caudicles ; and afterwards the 
extremities of the caudicles adhere to the pedicel. 
Before the flower expands the membranous sacks in- 
cluding the two pollen-masses open ; and the pollen- 
masses are left resting naked on the back of the 
rostellum. 

In Monachanthus, on the other hand, the two mem- 
branous sacks containing the rudimentary pollen- 
masses never open ; but they easily separate from each 
other and from the anther. The tissue of which they 
are formed is thick and pulpy. Like most rudi- 
mentary parts, the pollen-masses vary much in size 
and form; they are only about one-tenth of the bulk 
of those of the male ; they are flask-shaped (p, fig. 31), 
with the lower end greatly produced so as almost to 
penetrate the exterior or membranous sack. There is 
10 



202 VANDE.E. Chap. VII. 

no fissare along their lower surfaces for the protrusion 
of the caudicles. The exterior pollen-grains are square 
and have thicker walls than the interior grains, just as 
in the proper male pollen ; and, w^hat is very curious, 
each cell has its nucleus. Now, E. Brown states* that 
in the early stages of the formation of the pollen-grains 
of ordinary Orchids (as with other plants) a minute 
nucleus is often visible ; so that the rudimentary pollen- 
grains of Monachanthus apparently have retained — as 
is so general with rudiments in the animal kingdom — 
an embryonic character. Lastly, at the base, within 
each flask-shaped pollen-mass, there is a little mass of 
brown elastic tissue, — that is, a vestige of a caudicle, — 
which runs far up the pointed end of the flask, but 
does not (at least in some of the specimens) come to 
the surface, and could never be attached to any part of 
the pedicel. These rudimentary and enclosed caudicles 
are, therefore, utterly useless. Notwithstanding the 
small size and almost aborted condition of the female 
pollen-masses, when they were placed by Dr. Criiger 
within the stigma of a female plant they emitted " here 
and there a rudimentary tube." The petals then faded 
and the ovarium enlarged, but after a week it turned 
yellow and finally dropped off without bringing any 
seeds to perfection. This appears to me a very curious 
instance of the slow and gradual manner in which 
structures are modified ; for the female pollen-masses, 
which can never be naturally removed or applied to 
the stigma, still partially retain their former powers 
and function. 

Thus every detail of structure which characterises 
the male pollen-masses is represented in the female 
plant in a useless condition. Such cases are familiar to 



♦ 'Transactions of the Linnean Soc* vol. xvi, p. 711. 



Chap. VIL MYANTHUS BARBATUS. 203 

every naturalist, but can never be observed without 
renewed interest. At a period not far distant, natura- 
lists will hear with surprise, perhaps with derision, that 
grave and learned men formerly maintained that such 
useless organs were not remnants retained by inherit- 
ance, but were specially created and arranged in their 
proper places like dishes on a table (this is the simile 
of a distinguished botanist) by an Omnipotent hand 
" to complete the scheme of nature." 

The third form, Myanthus harhafus (fig. 31, B), is 
sometimes borne on the same plant together with the 
two preceding forms. The flowers differ greatly in 
external appearance, but not in essential structure, 
from those of both the other forms. They generally 
stand in a reversed position, compared with those of 
Catasetum tridentatum and of Monachanthus viridis, 
that is, with the labellum downwards. The labellum 
is fringed in an extraordinary manner with long 
papillae ; it has a quite insignificant medial cavity, 
at the hinder margin of which a curious curved and 
flattened horn projects, which represents the anvil-like 
projection on the labellum of the male G. callosum. 
The other petals and sepals are spotted and elongated, 
with the two lower sepals alone reflexed. The antennae 
are not so long as in the male C. tridentatum; they 
project symmetrically on each side of the horn-like 
process at the base of the labellum, with their tips, 
which are not roughened with papillae, almost entering 
the medial cavity. The stigmatic chamber is of nearly 
intermediate size between that of the male and female 
forms; it is lined with utriculi charged with brown 
matter. The straight and well-furrowed ovarium is 
nearly twice as long as that of the female Monachan- 
thus, but not so thick where it joins the flower ; the 
ovules are opaque and pulpy after having been kept 



204 VANDE.E. Chap. VIL 

in spirits, and resemble those of the female in all 
respects, but are not so numerous. I believe that I 
saw the nucleus projecting from the testa, but dare 
not, as in the case of the Monachanthus, speak posi- 
tively. The poUinia are about a quarter of the size 
of those of the male Catasetum, but have a perfectly 
well developed disc and pedicel. The pollen-masses 
were lost in the specimens examined by me ; but 
Mr. Keiss has given, in the Linnean Transactions, a 
drawing of them, showing that they are of due pro- 
portional size and have the proper folded or cleft 
structure, within which the caudicles are attached. 
Thus as both the male and female organs are in 
appearance perfect, Mi/anthus harhatus may be con- 
sidered as an hermaphrodite form of the same species, 
of which the Catasetum is the male and Monachan- 
thus the female. Nevertheless, the intermediate forms, 
which are common in Trinidad, and which resemble 
more or less closely the above described Myanthus, 
have never been seen by Dr. Criiger to produce seed- 
capsules. 

It is a highly remarkable fact, that this sterile 
hermaphrodite form resembles in its whole appearance 
and structure the males of two other species, namely, 
G. saceatum and more especially G. callosum, much 
more closely than it does either the male or female 
form of the same species. As all orchids, with the 
exception of a few in the present small sub-family, as 
well as all the members of several allied groups of 
plants, are hermaphrodites, there can be no doubt 
that the common progenitor of the Orchideae was 
an hermaphrodite. We may therefore attribute the 
hermaphrodite condition and the general appearance 
of Myanthus to reversion to a former state; and if 
so, the ancestors of all the species of Catasetum must 



Chap. VII. CATASETUM TRIDENTATUM. 205 

have resembled the males of G. saccatum and callosumf 
for as we have just seen, it is to these two plants that 
Myanthus presents so many striking resemblances.* 

Lastly I may be permitted to add that Dr. Criiger, 
after having carefully observed these three forms in 
Trinidad, fully admits the truth of my conclusion that 
Catasefum tridentatum is the male and Monaclianthus 
viridis the female of the same species. He further 
confirms my prediction that insects are attracted to 
the flowers for the sake of gnawing the labellum, and 
that they carry the pollen-masses from the male to the 
female plant. He says " the male flower emits a 
peculiar smell about twenty -four hours after opening, 
and the antennce assume their greatest irritability at 
the same time. A large humble-bee, noisy and quarrel- 
some, is now attracted to the flowers by the smell, 
and a great number of them may be seen every morning 
for a few hours disputing with each other for a place in 
the interior of the labellum, for the purpose of gnawing 
off the cellular tissue on the side opposite to the column, 
so that they turn their backs to the latter. As soon as 
they touch the upper antenna of the male flower, the 
pollen-mass, with its disc and gland, is fixed on their 
back, and they arc often seen flying about with this 
peculiar-looking ornament on them. I have never 
seen it attached except to the very middle of the 



♦ The male of ihe Indian ante- to reversion to a former state of 

\G^Ki(^A.bezoartica after castration the sptcies; for we have good 

produced horns of a widely dit- rea>oa to believe that any cause 

ferent shape from those of the which disturbs the constitution 

perfect male; find larger and leads to reversion. Myautlius, 

thicker than those occasionally though having- the organs of both 

produced by the female. We see sexes apparently perfect, is sterde; 

something of the sanie kind in the it has ti erelbre had its sexual 

horns of the common ox. I have constitution disturbed, and this 

remarked in my ' Descent of ]Man ' seems to have cause d it to revert 

(2nd edit. p. 50(j), that such in character to a former state, 
cases may probably be attributed 



206 VANDE^. Chap. VII. 

thorax. When the bee walks about, the poUen-masa 
lies flat on the back and wings ; but when the insect 
enters a female flower, always with the labellum turned 
upwards, the pollinium, which is hinged to the gland 
by elastic tissue, falls back by its own weight and rests 
on the anterior face of the column. When the insect 
returns backwards from the flower, the pollinia are 
caught by the upper margin of the stigmatic cavity, 
which projects a little beyond the face of the column ; 
and if the gland be then detached from the back of 
the insect, or the tissues which connect the pollinia 
with the caudicle, or this with the gland, break, fecun- 
dation takes place." Dr. Criiger sent me specimens 
of the humble-bees which he caught gnawing the 
labellum, and these consist of Euglossa nov. spec, ca- 
jennensis and piliventris. 

Cafasetum mentosum and a Monachanthus, according 
to Fritz Miiller,* grow in the same district of South 
Brazil ; and he easily succeeded in fertilising the 
latter with pollen from the former. The pollen-masses 
could be inserted only partially into the narrow 
stigmatic cleft ; but when this was done, a process of 
deglutition, as described under Cirrh?ea, commenced 
and was slowly completed. On the other hand, Fritz 
Miiller entirely failed in his attempts to fertilise the 
flowers of this Catasetum with its own pollen or with 
that from another plant. The pollinia of the female 
Monachanthus are very small ; the pollen-grains are 
variable both in size and shape ; the anther never 
opens, and the pollen-masses are not attached to 
the caudicle. Nevertheless, when these rudimentary 
pollen-masses, which can never naturally be removed 
from their cells, were placed on the slightly viscid 



* ' Bot. Zcitnng,' 1868, p. 630. 



Chap. VII. CATASETUM. 207 

stigma of the male Catasetum, tliey emitted tlieir 
tubes. 

The genus Catasetum is interesting to an unusual 
degree in several respects. The separation of the 
sexes is unknown amongst other Orchids, except per- 
haps in the allied genus Cycnoches. In Catasetum 
we have three sexual forms, generally borne on sepa- 
rate plants, but sometimes mingled together on the 
same plant; and these three forms are wonderfully 
different from one another, much more different than, 
for instance, a peacock is from a peahen. But the 
appearance of these three forms now ceases to be an 
anomaly, and can no longer be viewed as an unparal- 
leled instance of variability. 

This genus is still more interesting in its manner of 
fertilisation. We see a flower patiently waiting with 
its antennae stretched forth in a well-adapted position, 
ready to give notice whenever an insect puts its head 
into the cavity of the labellum. The female Mona- 
chanthus, not having true pollinia to eject, is destitute 
of antennae. In the male and hermaphrodite forms, 
namely Catasetum tridentatum and Myanthus harhafus, 
the pollinia lie doubled up, like a spring, ready to be 
instantly shot forth when the antennae are touched. 
The disc end is always projected foremost, and is coated 
with viscid matter which quickly sets hard and affixes 
the hinged pedicel firmly to the insect's body. The 
insect flies from flower to flower, till at last it visits a 
female plant : it then inserts one of the pollen-masses 
into the stigmatic cavity. As soon as the insect flies 
away the elastic caudicle, made weak enough to yield 
to the viscidity of the stigmatic surface, breaks, and 
leaves behind a pollen-mass ; then the pollen-tubes 
slowly protrude, penetrate the stigmatic canal, and the 
act of fertilisation is completed. Who would liave 



208 VANDE.E. Chap. VU 

been bold enough to have surmised that the propaga- 
tion of a species depended on so complex, so apparently 
artificial, and yet so admirable an arrangement ? 

I have examined three other genera placed by 
Lindley in the small sub-family of Catasetidse, namely, 
Mormodes, Cycnoches and Cyrtopodium. The latter 
plant was purchased by me under this name, and bore 
a flower-stem about four feet in height with yellowish 
bracts spotted with red ; but the flowers presented 
none of the remarkable peculiaiities of the three other 
genera, with the exception that the anther was hinged 
to a point projecting from the summit of the column, 
as in Catasetum. 

Mormodes ignea. — To show how difii cult it sometimes 
is to understand the manner in which an Orchid is 
fertilised, I may mention that I carefully examined 
twelve flowers,* trying various experiments and re- 
cording the results, before I could at all make out the 
meaning and action of the several parts. It was plain 
that the pollinia were ejected, as in Catasetum, but 
how each part of the flower played its proper part I 
could not even conjecture. I had given up the case 
as hopeless, until summing up my observations, the 
explanation presently to be given, and subsequently 
proved by repeated experiments to be correct, suddenly 
occurred to me. 

The flower presents an extraordinary appearance, 
and its mechanism is even more curious than its ap- 
pearance (fig. 32). The base of the column is bent 
backwards, at right angles to the ovarium or footstalk, 



♦ I must express my cordial two fine spikes, bearing an abun- 

thanks to Mr. Kucker/of West dance of flowers, and for having 

Hill, Wandsworth, lor having lent allowed me to keep the plant for 

me a plant of this Mormodes with a considerable time. 



Ohap. VII. 



MORMODES IGNEA< 



209 



and then resumes an upright position to near its 
summit, where it is again bent. It is, also, twisted in 
a unique manner, so that its front surface, including 



Fig. 32. 




MORMODES IGNEA. 

Lateral view of flower, with the upper sepal and the near upper petal 
cut off. 

N.B. The labellum in the drawing is a little lifted up, to show the de- 
pression on Its under surface, which ought to be pressed close down 
on the bent summit of the column. 



a. anther. 

•pd. pedicel of pollinium. 

s. stigma. 



I. labellum 
I. s. lateral 



the anther, rostellum, and the upper part of the stigma 
faces one side of the flower; this being either to the 



210 VANDEiE. Chap. VII. 

right or left, according to the position of the flower 
on the spike. The twisted stigmatic surface extends 
down to the base of the column and is hollowed out 
into a deep cavity at its upper end. The large viscid 
disc of the pollinium is lodged in this cavity close be- 
neath the rostellum ; and the rostellum is seen in the 
drawing (2^d.) covered by the bowed pedicel. 

The anther-case (a in the figure) is elongated and 
triangular, closely resembling that of Catasetum ; but 
it does not extend up to the apex of the column. The 
apex consists of a thin flattened filament, which from 
the analogy of Catasetum I suppose to be the produced 
filament of the stamen ; but it may be a prolongation 
of some other element of the column. In the bud- 
state it is straight, but before the flower expands, it 
becomes much bent by the pressure of the labellum. 
A group of spiral vessels runs up the column as far as 
the summit of the anther-case ; they are then reflexed 
and run some way down the anther-case. The point 
of reflexion forms a short thin hinge by which the top 
of the anther-case is articulated to the column beneath 
its bent summit. The hinge, although smaller than a 
pin's head in size, is of paramount importance ; for it 
is sensitive and conveys the stimulus from a touch to 
the disc of the pollinium, causing it to separate from 
its place of attachment. The hinge also serves to 
guide the pollinium during its ejection. As it has 
to convey the necessary stimulus to the disc, one may 
suspect that a portion of the rostellum, which lies in 
close contact with the filament of the anther, runs up 
to this point ; but I could not here detect any differ- 
ence in structure on comparing these parts with those 
of Catasetum. The cellular tissue round the hinge 
is gorged with fluid, and a large drop exudes when 
the anther is torn from the column during the ejection 



Chai-. VII. MORMODES IGNEA. 211 

of the pollinium. This gorged condition may perhaps 
facilitate the rupture of the hinge. 

The pollinium does not differ much from that of 
Catasetnm (see fig. 29, D, p. 183); and it lies in like 
manner curved round the rostellum, which is less protu- 
berant than in that genus. The upper and broad end of 
the pedicel, however, extends beneath the pollen-masses 
within the anther ; and these are attached by rather 
weak caudicles to a medial crest on its upper surface. 

The viscid surface of the large disc lies in contact 
with the roof of the stigmatic cavity, so that it cannot 
be touched by an insect visiting the flower. The 
anterior end of the disc is furnished with a small de- 
pendent curtain (dimly shown in fig. 32) ; and this, 
before the act of ejection, is continuously joined on 
each side to the upper margins of the stigmatic cavity. 
The pedicel is united to the posterior end of the disc ; 
but when the disc is freed, the lowermost part of the 
pedicel becomes doubly bent, so that it then appears 
as if attached by a hinge to the centre of the disc. 

The labellum is a highly remarkable structure : it 
is narrowed at its base into a nearly cylindrical foot- 
stalk, and its sides are so much reflexed as almost to 
meet at the back, forming a folded crest on the sum- 
mit of the flower. After rising up perpendicularly 
it arches over the apex of the column, against which it 
is firmly pressed down. The labellum at this point is 
hollowed out (even in the bud) into a slight cavity, 
which receives the bent summit of the column. This 
slight depression manifestly represents the large cavity, 
with thick fleshy walls, which insects gnaw, on the 
anterior surface of the labellum in the several species 
of Catasetum. Here by a singular change of function, 
the cavity serves to keep the labellum in its proper 
position on the summit of the column, but is, perhaps, 



212 VANDE^. Chap. VU 

likewise attractive to insects. In the drawing (fig. 32) 
tlie labellum has been forcibly raised a little up, so as 
to show the depression and the bent filament. In its 
natural position it may almost be compared to a huge 
cocked-hat, supported by a footstalk and placed on the 
head of the column. 

The twisting of the column, which I have seen in 
no other Orchid, causes all the important organs of 
fructification in the flowers on the left side of the 
spike to face to the left, and in all those on the right 
side to face to the right. So that two flowers taken 
from opposite sides of the same spike and held in 
the same relative position are seen to be twisted in 
opposite directions. One single flower, which was 
crowded by the others, was barely twisted, so that its 
column faced the labellum. The labellum is also 
slightly twisted : for instance, in the flower figured, 
which faced to the left, the midrib of the labellum was 
first twisted to the right-hand, and then to the left, but 
in a less degree, and being bent over it pressed on the 
posterior surface of the crooked summit of the column. 
The twisting of all the parts of the flower commences 
in the bud. 

The position thus acquired by the several organs is 
of the highest importance ; for if the column and 
labellum had not been twisted laterally, the pollinia, 
when shot forth, would have struck the overarching 
labellum and have then rebounded, as actually oc- 
curred with the single abnormal flower having a nearly 
straight column. If the organs had not been twisted 
in opposite directions on the opposite sides of the same 
crowded spike, so as always to face to the outside, there 
would not have been a clear space for the ejection of 
the pollinia and their adhesion to insects. 

When the flower is mature the three sepals hang 



Chap. VII. MORMODES IGXEA. 213 

down, but the two upper petals remain nearly upright. 
The bases of the sepals, and especially of the two 
upper petals, are thick and swollen and have a 
yellowish tint ; when quite mature, they are so gorged 
with fluid, that, if punctured by a fine glass tube, the 
fluid rises by capillary attraction to some height in it. 
These swollen bases, as well as the footstalk of the 
labellum, have a decidedly sweet and pleasant taste ; 
and I can hardly doubt that they are attractive to 
insects, for no free nectar is secreted. 

I will now endeavour to show how all the parts of 
the flower are co-ordinated and act together. The 
pedicel of the pollinium is bowed round the rostellum, 
as in Catasetum; in this latter genus, when freed, 
it merely straightens itself with force, in Mormodes 
something more takes place. If the reader will look 
forward to fig. 34 (p. 223), he will see a section of the 
flower-bud of the allied genus of Cycnoches, which 
difl'ers only in the shape of the anther and in the viscid 
disc having a much deeper dependent curtain. Now 
let him suppose the pedicel of the pollinium to be so 
elastic that, when freed, it not only straightens itself, 
but suddenly bends back on itself with a reversed 
curvature, so as to form an irregular hoop. The 
curved surface which was before in contact with 
the protuberant rostellum now forms the outside 
of the hoop. The exterior surface of the curtain, 
which depends beneath the disc, is not viscid; and 
it now lies on the anther-case, with the viscid surface 
of the disc on the outside. This is exactly what takes 
place w'ith Mormodes. But the pollinium assumes 
with such force its reversed curvature (aided, appa- 
rently, by a transverse curling outwards of the margins 
of the pedicel), that it not only forms itself into a 
hoop, but suddenly springs away from the protuberant 



214 VANDExE. Chap. VII 

face of tlie rostellum. As the two pollen-masses 
adhere, at first, rather firmly to the anther-case, the 
latter is torn off by the rebound ; and as the thin 
hinge at the summit of the anther-case does not yield 
so easily as the basal margin, the pollinium together 
with the anther-case is instantly swung upwards like a 
pendulum. But in the course of the upward swing 
the hinge yields, and the whole body is projected 
perpendicularly up in the air, an inch or two above and 
close in front of the terminal part of the labellum. If 
no object is in the way, as the pollinium falls down, 
it generally alights and sticks, though not firmly, on 
the folded crest of the labellum, directly over the 
column. I witnessed repeatedly all that has been 
here described. 

The curtain of the disc, which, after the pollinium 
has formed itself into a hoop, lies on the anther-ca^e, 
is of considerable service in preventing the viscid edge 
of the disc from adhering to the anther, and thus 
permanently retaining the pollinium in the form of a 
hoop. This would have been fatal, as we shall pre- 
sently see, to a subsequent movement of the pollinium 
which is necessary for the fertilisation of the flower. 
In some of my experiments, when the free action 
of the parts was checked, this did occur, and the 
pollinium, together with the anther-case, remained 
permanently glued together in the shape of an ir- 
regular hoop. 

I have already stated that the minute hinge by 
which the anther-case is articulated to the column, a 
little w^ay beneath its bent filamentary apex, is sen- 
sitive to a touch. I tried four times and found 
that I could touch with some force any other part ; 
but when I gently touched this point with the finest 
needle, instantly the membrane which unites the disc 



Chap. VII. MORMODES IGNEA. 215 

to the edges of the stigmatic cavity where it is lodged, 
ruptured, and the pollinium was shot upwards and fell 
on the crest of the labellum as just described. 

Now let us suppose an insect to alight on the 
folded crest of the labellum, and no other convenient 
landing-place is afforded, and then to lean over the 
front of the column so as to gnaw or suck the bases of 
the petals swollen with sweet fluid. The weight and 
movements of the insect would disturb the labellum 
and the bent underlying summit of the column ; and 
the latter, pressing on the hinge in the angle, would 
cause the ejection of the pollinium, which would in- 
fallibly strike the head of the insect and adhere to 
it. I tried by placing my gloved finger on the summit 
of the labellum, with the tip just projecting beyond 
its margin, and then gently moving my finger it was 
really beautiful to see how instantly the pollinium 
was projected upwards, and how accurately the viscid 
surface of the disc struck my finger and firmly 
adhered to it. Nevertheless, I doubt whether the 
weight and movements of an insect would suffice to 
thus act indirectly on the sensitive point ; but look 
at the drawing and see how probable it is that an 
insect leaning over would place its front legs over the 
edo:e of the labellum on the summit of the anther- 
case, and thus touch the sensitive point. The pol- 
linium would then be ejected, and the viscid disc 
would certainly strike and adhere to the insect's head. 

Before proceeding, it may be worth while to mention 
some of the early trials which I made. I pricked 
deeply the column in different parts, including the 
stigma, and cut off the petals, and even the labellum, 
without causing the ejection of the pollinium ; this, 
however, once happened when I cut rather roughly 
through the thick footstalk of the labellum, the fila- 



216 YANDEX. Chap. VII 

mentaiy summit of the column no doubt having been 
thus disturbed. When I gently prised up the anther- 
case at its base or on one side, the pollinium was 
ejected, but then the sensitive hinge would necessarily 
have been bent. When the flower has long remained 
expanded and is nearly ready for sj)ontaneous ejection, 
a slight jar on any part of the flower causes the 
action. Pressure on the thin pedicel of the pollinium, 
and therefore on the underlying protuberant rostellum, 
is followed by the ejection of the pollen-masses ; but 
this is not surprising, as the stimulus from a touch 
on the sensitive hinge has to be conveyed through 
this part of the rostellum to the disc. In Catasetum 
slight pressure on this point does not cause the act 
of ejection ; but in this genus the protuberant part of 
the rostellum does not lie in the course along which 
the stimulus has to be conveyed from the antennae 
to the disc. A drop of chloroform, of spirits of wine, or 
of boiling water placed on this part of the rostellum 
produced no effect ; nor, to my surprise, did exposure 
of the whole flower to vapour of chloroform. 

Seeing that this part of the rostellum was sensitive 
to pressure, and that the flower was widely open on 
one side, and being pre-occupied with the case of Cata- 
setum, I at first felt convinced that insects entered the 
lower part of the flower and touched the rostellum. 
Accordingly I pressed the rostellum with variously- 
shaped objects, but the viscid disc never once adhered 
in a proper manner to the object. If I used a thick 
needle, the pollinium, when ejected, formed a hoop 
round it with the viscid surface outside ; if I used a 
broad flat object, the pollinium struggled against it 
and sometimes coiled itself up spirally, but the disc 
either did not adhere at all, or very imperfectly. At 
file close of the twelfth trial I was in despair. The 



Chap. Vfl. MOEMODES IGNEA. 217 

strange position of the labellum, perched on the summit 
of the column, ought to have shown me that here was 
the place for experiment. I ought to have rejected 
the notion that the labellum was thus placed for no 
good purpose. This plain guide was overlooked, and 
for a long time I completely failed to understand the 
structure of the flower. 

We have seen that when the pollinium is ejected 
and swings upwards, it adheres by the viscid surface 
of the disc to any object projecting beyond the edge 
of the labellum directly over the column. When thus 
attached, it forms an irregular hoop, with the torn-off 
anther-case still covering the pollen-masses which are 
close to the disc, but protected from adhering to it 
by the dependent curtain. Whilst in this position 
the projecting and bowed part of the pedicel would 
effectually prevent the pollen-masses from being placed 
on the stigma, even supposing the anther-case to have 
fallen off. Now let us suppose the pollinium to be 
attached to an insect's head, and observe what takes 
place. The pedicel, when first separated from the ros- 
tellum, is damp; as it dries, it slowly straightens 
itself, and when perfectly straight the anther-case 
readily drops off. The pollen-masses are now naked, 
and they are attached to the end of the pedicel by 
easily ruptured caudicles, at the right distance and in 
a proper position for their insertion into the adhesive 
stigma, as soon as the insect visits another flower. 
Thus every detail of structure is now perfectly adapted 
for the act of fertilisation. 

When the anther-case drops off, it has performed its 
triple function ; namely, its hinge as an organ of sense, 
its weak attachment to the column as a guide causing 
the pollinium at first to swing perpendicularly upwards, 
and its lower margin, together with the curtain of the 



218 VANDE.E. CiiAP. VII 

disc, as a protection to the pollen-masses from being 
permanently glued to the viscid disc. 

From observations made on fifteen flowers, it was 
ascertained that the straightening of the pedicel does 
not occur until from twelve to fifteen minutes have 
elapsed. The first movement causing the act of ejec- 
tion is due to elasticity, and the second slow movement 
to the drying of the outer and convex surface ; but 
this latter movement differs from that observed in the 
poUinia of so many Vandeoe and Ophrese, for, when 
the pollinium of this Mormodes was placed in water, 
it did not recover the hoop-like form which it had at 
first acquired by elasticity. 

The flowers are hermaphrodites. The pollinia are 
perfectly developed. The elongated stigmatic surface 
is extremely viscid and abounds with innumerable 
utriculi, the contents of which shrink and become 
.coagulated after immersion for less than an hour in 
spirits of wine. When placed in spirits for a day, the 
utriculi were so acted on that they disappeared, and this 
I have not noticed in any other Orchid. The ovules, 
after exposure to spirits for a day or two, presented 
the usual semi-opaque, pulpy appearance common to 
all hermaphrodite and female Orchids. From the 
unusual length of the stigmatic surface I expected 
that, if the pollinia were not ejected from the excite- 
ment of a touch, the anther-case would have detached 
itself, and the pollen-masses would have swung down- 
wards and fertilised the stigma of the same flower. 
Accordingly, I left four flowers untouched ; after they 
had remained expanded from eight to ten days, the 
elasticity of the pedicel conquered the force of attach- 
ment and the pollinia were spontaneously ejected, but 
they did not fall on the stigma and were consequently 
Hasted. 



Chap VII. MOEMODES LUXATA. 219 

Although Mormodes ignea is an hermaphrodite, yet 
it must be as truly dioecious in function as Catasetum ; 
for as it takes from twelve to fifteen minutes before 
the pedicel of an ejected poUinium straightens itself 
and the anther-case drops off, it is almost certain that 
within this time an insect with a pollinium attached 
to its head would have left one plant and flown to 
another. 

Mormodes luxata. — This rare and fine species is ferti- 
lised in the same manner as Mormodes ignea, but differs 
in several important points of structure. The right 
and left sides of the same flower differ from one another 
even in a greater degree than in the last species. One 
of the petals and one of the sepals project at right 
angles to the column, while the corresponding ones 
stand upright and surround it. The upturned and 
twisted labellum is furnished with two large lateral 
lobes : of these one embraces the column, while the 
other stands partly open on the side where the one 
petal and sepal lie flat. Insects can thus easily enter 
the flower on this latter side. All the flowers on the 
left side of the spike are open on their left sides, while 
those on the right side are open on this side. The 
twisted column with all the important accessory parts, 
together with the rectangularly bent apex, closely re- 
semble the corresponding parts in M, ignea. But the 
under side of the labellum does not rest on and press 
against the rectangularly bent apex of the column. 
This stands free in the middle of a cup formed by the 
extremity of the labellum. 

I did not obtain many flowers fit for examination, 
as three had ejected their pollinia owing to the shocks 
received during their journey. I pricked deeply the 
labellum, column and stigma of some of the flowers 
without any effect ; but when I lightly touched with a 



220 VANDEiE. Chap. VLL 

needle, not the anther-Mnge as in the last species, but 
the apex of the column of one flower, the pollinium 
was instantly ejected. The bases of the petals and 
sepals are not swollen and succulent like those of 
M. ignea ; and I have little doubt that insects gnaw 
the labellum, which is thick and fleshy, with the same 
peculiar taste as in Catasetum. If an insect were to 
gnaw the terminal cup, it could hardly fail to touch 
the apex of the column, and then the pollinium would 
swing upwards and adhere to some part of the insect's 
body. The pedicels of the pollinia straighten them- 
selves and the anther-cases are cast off, in about fifteen 
minutes after the act of ejection. We may therefore 
confidently believe that this species is fertilised in the 
same peculiar manner as Mor modes ignea. 

Cyciioches ventricosum. — Mr. Yeitch was so kind as to 
send me on two occasions several flowers and flower- 
buds of this extraordinary plant. A sketch of a 
flower in its natural position, with one sepal cut off, 
is shown at fig. 33 (p. 222), and a longitudinal section 
through a young bud at fig. 34 (p. 223). 

The labellum is thick and fleshy, wath the usual 
taste of this organ in the CatasetidDs ; it resembles in 
shape a shallow basin turned upside down. The two 
other petals and the three sepals are reflexed. The 
column is almost cylindrical, thin, flexible, elastic 
and of extraordinary length. It curves round so 
as to bring the stigma and anther opposite to and 
beneath the convex surface of the labellum. The 
a23ex of the column is not nearly so much produced as 
in Mormodes and Catasetum. The pollinia closely 
resemble those of Mormodes ; but the disc is larger, 
and its curtain, which is fringed, is so large that it 
covers the whole entrance into the stigmatic chamber. 
The structure of these parts is best seen in the section 



Chap. VTI. CYCNOCHES VENTPJCOSUM. 221 

fig. 34 ; in which the pedicel of the pollinium has not 
as yet become separate from the rostellum, but the 
future line of separation is shown by a line (dotted 
in the figure) of hyaline tissue. The filament of the 
anther (/, fig. 34) has not as yet grown to its full 
length. When fully developed it bears two little leaf- 
like appendages which lie on the anther. Lastly, 
on the sides of the stigma there are two slight 
protuberances (fig. 33), which apparently represent 
the antennae of Catasetum, but have not the same 
function. 

Neither the labellum nor the protuberances on the 
sides of the stigma are at all sensitive ; but when on 
three occasions I momentarily touched the filament, 
between the little leaf-like appendages, the pollinium 
was ejected in the same manner and through the 
same mechanism as in Mormodes ; but it was thrown 
only to the distance of about an inch. If the filament 
had been touched by an object which had not been 
quickly removed, or if by an insect, the viscid disc 
would certainly have adhered to it. Mr. Veitch informs 
me that he has often touched the end of the column, 
and the pollinium has adhered to his finger. When 
the pollinium is ejected, the pedicel forms a hoop, with 
the exterior surface of the curtain of the disc resting 
on and covering the anther. In about fifteen minutes 
the pedicel straightens itself, and the anther-case 
drops off ; and now the pollinium is in a right position 
for fertilising another flower. As soon as the viscid 
matter on the under surface of the disc is exposed to 
the air it quickly changes colour and sets hard. It 
then adheres with surprising force to any object. 
From these various facts and from the analogy of the 
other Catasetidse, we may conclude that insects visit 
the flowers for the sake of gnawing the labellum : 



222 



YANDEX. 



Chap. YII. 



but it cannot be predicted whether they alight on the 
surface which is uppermost in the drawing (fig. 33) and 



Fig. 33. 




Cycnoches ventrhcosum. 
Flower viewed in its natural dependent position. 



c. column, after the ejection of 
the pollinium together with 
the anther. 

/. filament of anther. 



s. stigmatic cavity. 

L, labellum. 

pet. the two lateral petals. 

j sep. sepals. 



then crawl over the margin so as to gnaw the convex 
surface, and in doing so touch with their abdomens 



Chap. VII. 



CYCNOCHES VENTRICOSUM. 



223 



the extremity of the column, or whether they first 
alight on this part of the column ; but in either case 
they would cause the ejection of the pollinia, which 
would adhere to some part of their bodies. 
The specimens which I examined Tvere certainly 

Fig. 34. 




DlAQRAMMATIC SECTION OF A FlOWEE-BUD, THE COLUMN PLACED 

UPRIGHT. 



d. disc of polliQium with the depen- 
dent curtain. 

s. stigraatic chamber. 

g. stigmatic canal leading to the 
ovarium. 



a. anther. 

/. filament of anther. 

p. pollen-mass. 

pd. pedicel of pollinium, barely se- 
parated as yet from the ros- 
tellum. 

male plants, for the pollinia were well developed. The 
stigmatic cavity was lined with a thick layer of pulpy 
matter which was not adhesive. But as the flowers 
cannot possibly be fertilised until the pollinia have 
been ejected, together with the great curtain which 
covers the whole stigmatic surface, it may be that 



224 VANDE^. Chap. VH. 

this surface becomes j^t a later period adhesive so as to 
secure the pollen-masses. The ovules when kept for 
some time in alcohol were filled with brownish pulpy 
matter, as is always the case with perfect ovules. 
Therefore it appears that this Cycnoches must be an 
hermaphrodite ; and Mr. Bateman, in his work on the 
Orchideae, says that the present species produces seeds 
without being, as I understand, artificially fertilised ; 
but how this is possible is unintelligible to me. On 
the other hand. Beer says * that the stigma of Cyc- 
noches is dry, and that the plant never sets seeds. 
According to Lindley C. ventricosum produces on the 
same scape flowers with a simple labellum, others with 
a much segmented and differently coloured labellum 
(viz., the so-called C. egertonianum), and others in an 
intermediate condition. From the analogous differ- 
ences in the flowers of Catasetum, we are tempted to 
believe that we here have male, female, and herma- 
phrodite forms of the same species of Cycnoches. t 

I have now finished iny description of the CatasetidsB 
as well as of many other Vandese. The study of these 
wonderful and often beautiful productions, with all 
their many adaptations, with parts capable of move- 
ment, and other parts endowed with something so like, 
though no doubt different from, sensibility, has been to 
me most interesting. The flowers of Orchids, in their 
strange and endless diversity of shape, may be com- 



* QiK.tedby Irmisfh, 'Eeitrage IMr. Bateman also says tlat C. 

zur Biologic del- Orchideen,' 1853, egertouiannm lias been known to 

p. 22. produce in Guatemala and once 

t Lindley's * Vegetable King- in England scapes of a purplc- 

dom,' 1853, p. 177. He has also floNvered and widely different spe- 

jmblished in the 'Botanical I!egis- cies of Cycnoches ; but that it 

ter,' fol. 1951, a caso of two forms generally produces in Eiigland 

appearing on the same scape of scapes of the common yellow C, 

another species of Cycnoches. ventricosum. 



Chap. VII. VANDEiE. 225 

pared with the great vertebrate class of Fish, or still 
more appropriately with tropical Homopterous insects, 
which appear to us as if they had been modelled 
in the wildest caprice, but this no doubt is due to 
our ignorance of their requirements and conditions 
of life. 



11 



226 CYPEIFEDEiE. OflAP. VI II. 



CHAPTEE VIII. 

CYPRIPEDE.E— HOMOLOGIES OF THE FLOWERS OF 
OECHIDS. 

Cypripedium, differs much from all other Orchids — ^Labellum in the 
form of a slipper with two small orifices by which insects can escape 
— Manner of fertilisation by small bees of the genns Andrena — 
Homological nature of the several parts of the flowers of the Orchidese 
— Wonderful amount of modification which they have undergone. 

We have now arrived at Lindley's last and seventh 
tribe, including, according to most botanists, only a 
single genus, Cypripedium, which differs from all 
other Orchids far more than any other two of these 
do from one another. An enormous amount of ex- 
tinction must have swept away a multitude of inter- 
mediate forms, and has left this single genus, now 
widely distributed, as a record of a former and more 
simple state of the great Orchidean Order. Cypripe- 
dium possesses no rostellum ; for all three stigmas 
are fully developed, though confluent. The single 
anther, which is present in all other Orchids, is here 
rudimentary, and is represented by a singular shield- 
like projecting body, deeply notched or hollowed out 
on its lower margin. There are two fertile anthers 
which belong to an inner whorl, represented in ordinary 
Orchids by various rudiments. The grains of pollen 
are not united together by threes or fours, as in so 
many other genera, nor are they tied together by 
elastic threads, nor furnished with a caudicle, nor 
cemented into waxy masses. The label lum is of 



Chat. VIII. 



CYPRIPEDIUM. 



227 



large size, and is a compound organ as in all other 
Orchids. 

The following remarks apply only to the six species 
which I have examined, namely, G, harhatum, purpu- 
ratuniy insigne, venustum, piibescens and acaule ; though 
I have casually looked at some other kinds. The 
basal part of the labellum is folded round the short 

Fig. 35. 






Cypripedium. 



a. anther. 

a', rudimentary, shield-like anther, 

s. stigma. 

/, labellum. 

A. Flower viewed from above, with 
the sepals and petals, excepting 
the labellum, partly cut off". 
The labellum has been slightly 
depressed, so that the dorsal 



surface of the stigma is ex- 
posed ; the edges of the label- 
lum have thus become a little 
separated and the toe or ex- 
tremity stands lower than is 
natural. 
Side view of column, with all 
the sepals and petals removed. 



column, so that its edges nearly meet along the dorsal 
surface ; and the broad extremity is folded over in a 
peculiar manner, forming a sort of shoe, which closes 
up the end of the flower. Hence arises the English 
name of Ladies'-slipper. The overarching edges of the 
labellum are inflected or sometimes only suiootli and 



228 CYPKIPEDE^. Chap. VIU 

polished internally ; and this is of much importance, 
as it prevents insects which have once entered the 
labellum from escaping through the great opening in 
the upper surface. In the position in which the flower 
grows, as here represented, the dorsal surface of the 
column is uppermost. The stigmatic surface is slightly- 
protuberant, and is not adhesive; it stands nearly 
parallel to the lower surface of the labellum. With a 
flower in its natural state, the margin of the dorsal 
surface of the stigma can be barely distinguished be- 
tween the edges of the labellum and through the 
notch in the rudimentary, shield-like anther (a') ; but 
in the drawing (s, fig. A) the margin of the stigma has 
been brought outside the edges of the depressed la- 
bellum, and the toe is a little bent downwards, so that 
the flower is represented as rather more open than it 
really is. The edges of the pollen-masses of the two 
lateral anthers (a) can be seen through the two small 
orifices or open spaces in the labellum (fig. A) on 
each side, close to the column. These two orifices are 
essential for the fertilisation of the flower. 

The grains of pollen are coated by and immersed in 
viscid fluid, which is so glutinous that it can be drawn 
out into short threads. As the two anthers stand be- 
hind and above the lower convex surface (see fig. B) of 
the stigma, it is impossible that the glutinous pollen 
can without some mechanical aid get on to this, the 
efficient surface of the stigma. The economy here 
shown by Nature in her manner of gaining the same 
end is surprising. In all the other Orchids seen by 
me, the stigma is viscid and more or less concave, by 
which means the dry pollen, transported by means of 
the viscid matter secreted by the rostellum or modified 
stigma, is retained. In Cypripedium the pollen is 
glutinous, and assumes the function of viscidity, which 



Chap. Vin. CYPRIPEDIUM. 229 

in all other Orchids except Vanilla belongs exclusively 
to the rostellum and the two confluent stigmas. These 
latter organs, on the other hand, in Cypripedium en- 
tirely lose their viscidity, and at the same time become 
slightly convex, so as more effectually to rub off the 
glutinous pollen adhering to the body of an insect. 
Moreover in several of the North American species, 
as in G. acaule and imhescens, the surface of the stigma 
is beset, as Professor Asa Gray remarks, * " with 
minute, rigid, sharp-pointed papillae, all directed for- 
wards, which are excellently adapted to brush off the 
pollen from an insect's head or back." There is one 
partial exception to the above .rule of the pollen of 
Cypripedium being viscid while the stigma is not 
viscid and is not convex ; for in G. acaule the pollen 
is more granular and less viscid, according to Asa 
Gray, than in the other American species, and in 
G. acaule alone the stigma is slightly concave and 
viscid. So that here the exception almost proves the 
truth of the general rule. 

I have never been able to detect nectar within the 
labellum, and Kurrj makes the same remark with 
respect to G. calceolus. The inner surface of the la- 
bellum, however, in those species which I examined, 
is clothed with hairs, the tips of which secrete little 
drops of slightly viscid fluid. And these if sweet or 
nutritious would suffice to attract insects. The fluid 
when dried forms a brittle crust on the summits of the 
hairs. Whatever the attraction may be, it is certain 
that small bees frequently enter the labellum. 

Formerly I supposed that insects alighted on the 
labellum and inserted their proboscides through either 



* 'American Journal of Science,' t 'Bedeutung der Ncktnrien^ 

vol. xxxiv. 18G2, p. 428. 1838, p. 29. 



230 CYPRIPEDE^. Chap. VIIL 

of the orifices close to the anthers ; for I found that 
when a bristle was thus inserted the glutinous pollen 
adhered to it, and could afterwards be left on the 
stigma ; but this latter part of the operation was not 
well effected. After the publication of my book 
Professor Asa Gray wrote to me * that he was convinced 
from an examination of several American species that 
the flowers were fertilised by small insects entering the 
labellum through the large opening on the upper sur- 
face, and crawling out by one of the two small orifices 
close to the anthers and stigma. Accordingly I first 
introduced some flies into the labellum of G. puhescens, 
through the large upper opening, but they were either 
too large or too stupid, and did not crawl out properly. 
T then caught and placed within the labellum a very 
small bee which seemed of about the right size, namely, 
Andrena ])arvula, and this by a strange chance proved, 
as we shall presently see, to belong to the genus on 
v/hich in a state of nature the fertilisation of C. calceo- 
lus depends. The bee vainly endeavoured to crawl out 
again the same way by which it had entered, but always 
fell backwards, owing to the margins being inflected. 
The labellum thus acts like one of those conical traps 
with the edges turned inwards, which are sold to catch 
beetles and cockroaches in the London kitchens. It 
could not creep out through the slit between the folded 
edges of the basal part of the labellum, as the elongated, 
triangular, rudimentary stamen here closes the passage. 
Ultimately it forced its way out through one of the 
small orifices close to one of the anthers, and was 
found when caught to be smeared with the glutinous 
pollen. I then put the same bee back into the label- 
lum ; and again it crawled out through one of the small 



* See also ' Aiucrican Journal of Science,' vol. xxxiv. 18G2, p. 427. 



Chap. VIII. CYPEIPEDIUM. 231 

orifices, always covered with pollen. I repeated the 
operation five times, always with the same result. I 
afterwards cut away the labellum, so as to examine the 
stigma, and found its whole surface covered with pollen. 
It should be noticed that an insect in making its escape 
must first brush past the stigma and afterwards one of 
the anthers, so that it cannot leave pollen on the 
stigma, until being already smeared with pollen from 
one flower it enters another ; and thus there will be a 
good chance of cross-fertilisation between two distinct 
plants. Delpino* with much sagacity foresaw that 
some insect would be discovered to act in this manner ; 
for he argued that if an insect were to insert its pro- 
boscis, as I had supposed, from the outside through 
one of the small orifices close to one of the anthers, the 
stigma would be liable to be fertilised by the plant's 
own pollen : and in this he did not believe, from 
having confidence in what I have often insisted on — 
namely, that all the contrivances for fertilisation are 
arranged so that the stigma shall receive pollen from 
a distinct flower or plant. But these speculations are 
now all superfluous ; for, owing to the admirable ob- 
servations of Dr. H. Miiller, t we know that Cijpvi- 
'pedium caleeolus in a state of nature is fertilised in the 
manner just described by bees belonging to five species 
of Andrena. 

Thus the use of all the parts of the flower, — namely, 
the inflected edges, or the polished inner sides of the 
labellum, — the two orifices and their position close to 
the anthers and stigma, — the large size of the medial 
rudimentary stamen, — are rendered intelligible. An 



* ' Fecondazione ndle Piante xxv. III. Folge, v. Bd. p. 1 : see 

Antocarpee,' 1867, p. 20. also ' Bcfruclituug der BJumcu/ 

t 'Yerh. d. Nat. Ver. fur Pr. 1873, p. 76. 
Kheinland und Wcstfal ' Jakrg. 



232 HOMOLOGIES OF THE Chap. Till 

msect which enters the labellum is thus compelled to 
crawl out by one of the two narrow passages, on the 
sides of which the pollen-masses and stigma are placed. 
We have seen that exactly the same end is gained in 
the case of Coryanthes by the labellum being half- 
filled with secreted fluid ; and in the case of Pterostylis 
and some other Australian Orchids by the labellum 
being irritable, so that when touched by an entering 
insect it shuts up the flower, with the exception of a 
single narrow passage.* 

Homological Nature of the several Farts of the Flowers of 
the Orchidese. 

The theoretical structure of few flowers has been so 
largely discussed as that of the Orchidese ; nor is this 
surprising, seeing how unlike they are to common 
flowers ; and here will be a convenient place for con- 
sidering this subject. No group of organic beings can 
be well understood until their homologies are made 
out ; that is, until the general pattern, or, as it has 
often been called, the ideal type, of the several mem- 
bers of the group is intelligible. No one member 
may now exist exhibiting the full pattern ; but this 
does not make the subject less important to the natu- 
ralist, — probably makes it more important for the 
full understanding of the group. 

The homologies of any being, or group of beings. 



* Selenipedium palmifolium is tlie fish-pot system, i. e. a funnel- 

oue of the Cypripedese, and shaped opening conducts into it, 

according to Dr. Criiger (' Journ. and insects find it difficult to 

Linn. Soc. Bot.' vol. viii. 1864, p. escape through the same. The 

] 84) bears very fragrant flowers, only other opening near the base 

which "in all probability are of tlie labellum is partly closed 

always impregnated by insects. by the sexual apparatus, and the 

The labellum is, like some Aris- insect has to force its way out 

tolochia-flowers, constructi d after there." 



Chap. VIII. FLOWERS OF ORCHIDS. 233 

can be most surely made out by tracing their embryo- 
logical development wlien that is possible ; or by the 
discovery of organs in a rudimentary condition ; or by 
tracing, through a long series of beings, a close gradation 
from one part to another, until the two parts or organs, 
though employed for widely different functions and 
most unlike each other, can be joined by a succession 
of short links. No instance is known of a close gradation 
between two organs, unless they are homologically one 
and the same organ. 

The importance of the science of Homology rests on 
its giving us the key-note of the possible amount of 
difference in plan within any group ; it allows us to 
class under proper heads the most diversified organs ; 
it shows us gradations which would otherwise have 
been overlooked, and thus aids us in classification ; it . 
explains many monstrosities ; it leads to the detection 
of obscure and hidden parts, or mere vestiges of parts, 
and shows us the meaning of rudiments. Besides 
these uses. Homology clears away the mist from such 
terms as the scheme of nature, ideal types, archetypal 
patterns or ideas, &c. ; for these terms come to express 
real facts. The naturalist, thus guided, sees that all 
homologous parts or organs, however much they may 
be diversified, are modifications of one and the same 
ancestral organ ; in tracing existing gradations he 
gains a clue in tracing, as far as that is possible, the 
probable course of modification through which beings 
have passed during a long line of generations. He 
may feel assured that, whether he follows embryo- 
logical development, or searches for the merest rudi- 
ment, or traces gradations between the most different 
beings, he is pursuing the same object by different 
routes, and is tending towards the knowledge of the 
actual progenitor of the group, as it once grew and 



234 HOMOLOGIES OF THE Chap. VIII. 

lived. Thus the subject of Homology gains largely 
in interest. 

Although this subject, under whatever aspect it be 
viewed, will always be most interesting to the student 
of nature, it is very doubtful whether the following 
details on the homological nature of the flowers of 
Orchids will possess any interest for the general reader. 
If, indeed, he cares to see how much light an acquaint- 
ance with homology, though far from perfect, throws 
on a subject, this will, perhaps, be nearly as good an 
instance as could be given. He will see how curiously 
a flower may be moulded out of many separate organs, 
— how perfect the cohesion of primordially distinct 
parts may become, — how organs may be used for pur- 
poses widely different from their proper uses, — how 
other organs may be entirely suppressed, or leave mere 
useless emblems of their former existence. Finally, 
he will see how enormous has been the amount of 
change which these flowers have undergone from their 
parental or typical form. 

Kobert Brown first clearly discussed the homologies 
of Orchids,* and left, as might be expected, little to 
be done. Guided by the general structure of mono- 
cotyledonous plants and by various considerations, 
he propounded the doctrine that the flower properly 
consists of three sepals, three petals, six anthers in 
two whorls or circles (of which only one anther belong- 
ing to the outer whorl is perfect in all the common 
forms), and of three pistils, with one of them modified 
into the rostellum. These fifteen organs are arranged 
as usual, alternately, three within three, in five whorls. 
Of the existence of three of the anthers in two of 



* I believe his latest views are the ' Linnean Transactions,' vol. 
given in his celebrated paper, read xvi. p. GSo. 
Nov. 1-15, 18:51, and imblished in 



Dhap. VIII. FLOWJTES OF OKCHIDS. 235 

the whorls, K. Brown offers no sufficient evidence, but 
believes that they are combined with the labellum, 
whenever that organ presents crests or ridges. In 
these views Brown is followed by Lindley.* 

Brown traced the spiral vessels in the flower by 
making transverse sections, f and only occasionally, as 
far as it appears, by longitudinal sections. As spiral 
vessels are developed at a very early period of growth, 
and this circumstance always gives much value to a 
part in making out homologies ; and as they are ap- 
parently of high functional importance, though their 
function is not well known, it appeared to me, guided 
also by the advice of Dr. Hooker, to be worth while to 
trace upwards all the spiral vessels from the six groups 
surrounding the ovarium. Of the six ovarian groups 
of vessels, I will call (though not correctly) that under 
the labellum the anterior group ; that under the 
upper sepal the posterior group ; and the two groups 
on the two sides of the ovarium the antero-lateral and 
postero-lateral groups. 

The result of my dissections is given in the following 
diagram (fig. 36). The fifteen little circles represent 



* Professor Asa Gray has de- the union of one petal with two 

scribed in the ' American Journal petaloid stamens, 

of Science,' July 1866, a monstrous f ' Linn. Transact.' vol. xvi. p. 

flower of Ci/pripedium candidum, 696-701. Link in liis ' Bemer- 

and remarks on it, " here we have kungen Uber der Ban der Orchi- 

(and perhaps the iirst direct) deen'('BotanischeZeitung,' 1849, 

demonstration that the orchideous p. 745) seems to have also trustt d 

type of flower has two staminal to transverse sections. Had he 

verticils, as Brown always in- traced the vessels upwards I can- 

si.sted.'' Dr. Criiger also advances not believe that he would have 

evidence ( ' Journ. Linn. Soc. disputed Brown's view of the 

Bot.' vol. viii. 1861, p. 132) in nature of the two anthers in 

favour of the presence of five Cypripedium. Brongniart in liia 

whorls of organs ; but he denies admirable paper (' Annales des 

that the homologies of the parts Sciences Nat.' torn. xxiv. 1831 1 

can be deduced from the course of incidentally shows tlio course of 

the vessLils, and lie does not admit some of the spiral vessels, 
that the labfllum is formed by 



236 



HOMOLOGIES OF THE 



CUAP. VIII 



SO many groups of spiral vessels, in every case traced 
down to one of the six large ovarian groups. They 
alternate in five whorls, as represented ; but I have not 
attempted to give the actual distances at which they 
stand apart. In order to guide the eye, the three 
central groups running to the three pistils are con- 
nected by a triangle. 

Fig. 36. 
Upper or posterior sepal. 



Upper ^ 
petal. 



Upper 
petal. 




Labellum. 

Section of the Flower of an Orchid. 

The little circles show the position of the spiral vessels. 



Ai 



SS. Stigmas; Sr, stigma modified 
into the rostellum. 
Fertile anther of the outer 
whorl ; Ag A3, anthers of the 
same whorl combined with 
the lower petal, forming the 
labellum. 



flj Gj. Rudimentary anthers of the 
inner whorl (fertile in Cypri- 
pedium), generally forming 
the clinandrum ; Oj, third 
anther of the same whorl, 
when present, forming the 
front of the column. 



Five groups of vessels run into the three sepals 
together with the two upper petals ; three enter the 



CiiAP. VIII. FLOWEKS OF OECHIDS. 237 

labellum ; and seven run up the great central column. 
These vessels are arranged, as may be seen, in rays 
proceeding from the axis of the flower ; and all on the 
same ray invariably run into the same ovarian group ; 
thus the vessels supplying the upper sepal, the fertile 
anther (Ai), and the upper pistil or stigma (i. e. the 
rostellum S^), all unite and form the posterior ovarian 
group. Again, the vessels supplying, for instance, the 
left lower sepals, the corner of the labellum and one 
of the two stigmas (S) on the same side, unite and form 
the antero-lateral group; and so with all the other 
vessels. 

Hence, if the existence of groups of spiral vessels 
can be trusted, the flower of an Orchid certainly 
consists of fifteen organs, in a much modified and 
confluent condition. We see three stigmas, with the 
two lower ones generally confluent, and with the upper 
one modified into the rostellum. We see six stamens, 
arranged in two whorls, with generally one alone (Ai) 
fertile. In Cypripedium, however, two stamens of 
the inner whorl {a^ and a^ are fertile, and in other 
Orchids these two are represented more plainly in 
various ways than the remaining stamens. The third 
stamen of the inner whorl (^3), when its vessels can 
be traced, forms the front of the column : Brown 
thought that it often formed a medial excrescence, 
or ridge, cohering to the labellum ; or, in the case of 
G-lossodia,* a filamentous organ, freely projecting in 
front of the labellum. The former conclusion does 
not agree with my dissections; about Glossodia I 
know nothing. The two infertile stamens of the outer 
whorl (A2, A3) were believed by Brown to be only 
occasionally represented, and then by lateral excre- 

* See Brown's obsevvatioTis 'Plautte Asiaticse rarioies/ 1830, 
■under Apoatabia in Wallicb'a p. 74. 



238 HOMOLOGIES OF THE Chap. VIII. 

scences on tlie labellum ; but I find the corresponding 
vessels invariably present in the labellum of every 
Orchid examined, — even when the labellum is very 
narrow or quite simple, as in Malaxis, Herminium, 
or Habenaria. 

We thus see that an Orchid-flower consists of five 
simple parts, namely, three sepals and two petals ; 
and of two compounded parts, namely, the column and 
labellum. The column is formed of three pistils, and 
generally of four stamens, all completely confluent. 
The labellum is formed of one petal with two petaloid 
stamens of the outer whorl, likewise completely con- 
fluent. I may remark, as making this fact more 
probable, that in the allied Marantacese the stamens, 
even the fertile stamens, are often petaloid, and 
partially cohere. This view of the nature of the label- 
lum explains its large size, its frequently tripartite 
form, and especially the manner of its coherence to the 
column, unlike that of the other petals.* As rudi- 
mentary organs vary much, we can thus perhaps 
understand the variability, which as Dr. Hooker informs 
me is characteristic of the excrescences on the labellum. 
In some Orchids which have a spur-like nectary, the 
two sides are apparently formed by the two modified 
stamens ; thus in Gymnadenia conopsea (but not in 
Orchis fijramidalis), the vessels, proceeding from the 
two antero-lateral ovarian groups, run down the sides 
of the nectary ; those from the single anterior group 
run down the exact middle of the nectary, then 
returning up the opposite side form the mid-rib of the 
labellum. The sides of the nectary being thus formed of 
two distinct organs, apparently explains the tendency, 



* Link remarks on the meaner the cohimn in his " Beinerkungen' 
of coherence of the labellum to iu ' Bot. Zeitung,' 1849, p. 745. 



CJhap. VIII. 



FLOWERS OF ORCHIDS. 



239 



as in Calanthe, Orchis morio, &c., to the bifurcation of 
its extremity. 

The number, position, and course of all the spiral 
vessels exhibited in the diagram (fig. 36) were observed 
in some Vandese and Epidendrese.* In the Malaxese 



♦ It may he advisable to give a 
few details od the flowers which 
I dissected ; but I looked to special 
points, such as tlie course of the 
vessels in the labellum, in many 
cases not worth here giving. In 
the Vandcfe I traced all the ves- 
sels in Catasetiim tridentatum and 
saccatum; the great group of 
vessels going to the rostellum 
separate (as likewise in Mormodes) 
from the posterior ovarian group, 
beneath the bifurcation supplying 
the upper sepal and fertile anther ; 
the anterior ovarian group runs 
a little way along the labellum 
before it bifuicates and sends a 
group (a^) up the front of the 
column; the vessels proceedmg 
from the postero-lateral group run 
up the back of tl^.e column, on 
each side of those running to the 
fertih' anther, and do not go to 
the edges of the clinandrum. In 
Acropera luteola the base of the 
column, where the labellum is 
attached, is much produced, and 
the vessels of the whole auterior 
ovarian group are similarly pro- 
duced; those (as) going up the 
front of the column are abruptly 
reflected back ; the vessels at the 
point of reflexion are curiously 
hardened, flattened, and produced 
into odd crests and points. In 
an Oncidium I traced the vessels 
S^ to the viscid gland of the polli- 
nium. Among theEpidemlresel 
traced all the vessels in a Cattleya ; 
and all in Evelyna carkmta except 
03, which I did not search for. In 
the Malaxese I trace d nlVinLiparis 
pendula except a,, which I do not 
believe is present. In Malaxis 
l^aladosa I traced nearly all the 



vessels. In Cypripedium harhafnm 
and pupuratum I traced all except 
ttj, which I am nearly sure does 
not exist. In the Neottea; I traced 
in Cephalanthera qrandijiora all 
the vessels, excepting that to the 
aborted rostellum and those to 
the two auricles a^ and a.,, which 
were certainly absent. In Epi- 
pactis I traced all excepting ai,a2, 
and rtj, whifh are certainly absent. 
In Spiranthes autumnalis the 
vessel Sr runs to the bottom of 
the fork of the rostellum : there 
are no vessels to the membranes 
of the clinandrum in this Orchid 
nor in Goody era. In none of tlie 
Ophreoe do the vessels aj, a^, and 
ttg occur. In Orchis ptjramidalis 
I traced all the others, including 
two to the two separate stigmas : 
in this species the contrast between 
the vessels of the labellum and 
of the other sepals and petals is 
striking, as in the latter the ves- 
sels do not branch, whilst the 
labellum has three vessels the 
lateral ones running of course into 
the antero-lateral ovarian group. 
In Gymnadenia conopsca I traced 
all the vessels ; but 1 am not sure 
wliether the vessels supplying the 
sides of the upper sepal do not, as 
in the allied Habenaria, wander 
from their proper course and enter 
the postero-lateral ovarian group : 
the vessel Sr, going to the rostel- 
lum. enters the little folded crest 
of membrane, which projects be- 
tween the bases of the anther-cells. 
Lastly, in Habenaria chlorantha I 
traced all the vessels, excepting 
as in the other Ophreae the three 
of the inner staminal whorl, and I 
looked Cixrofully for a^ : the vessel 



240 HOMOLOGIES OF THE Chap. VIEL 

all were observed excepting a^, which is the most 
difficult one to trace, and apparently is oftenest absent. 
In the CypripedccTe, again, all were traced except ag,* 
which, I feel pretty sure, was here really absent : in 
this tribe the stamen (Ai) is represented by a con- 
spicuous shield-like rudiment, and ai and a^ are 
developed into two fertile anthers. In the Ophre^B 
and NeottCcTB all were traced, with the important 
exception of the vessels belonging to the three stamens 
(«!, ^2, and %) of the inner whorl. In Gejjhalanthera 
grandiflora, I clearly saw a^ proceeding from the 
anterior ovarian group, and running up the front of 
the column. This anomalous Orchid has no rostellum, 
and the vessel marked S^ in the diagram was entirely 
absent, though seen in every other species. 

Although the two anthers {a^ and a^ of the inner 
whorl are not fully and normally developed in any 
Orchid, excepting Cypripedium, their rudiments are 
generally present and are often utilised ; for they often 
form the membranous sides of the cup-like clinandrum 
on the summit of the column, which includes and pro- 
tects the pollen-masses. These rudiments thus aid 
their fertile brother-anther. In the young flower-bud 



supplying the fertile anther runs tion of a freo filament in front of 

up the connective membrane be- the labelhim, as in the ease of 

tween the two anther-cells, but Glossodia before mentioned ; and 

does not bifurcate : the ves-el to tliis will perhaps account for thu 

the rostellum runs up to the top absence of spiral vessels, proceed- 

of the shoulder or ledge beneath ing from the anterior ovarian 

tlie connective membrane of tlie group and coalescing with the 

anther, but does not bifurcate and column. In Uropedium, a genus 

extend to the two widely-separated which A. Brongniart (' Annal. 

viscid discs. des. Sc. Nat.,' 3rd series, Bot. torn. 

* From Irmisch's ('Beitrdge xiii. p. 114) considers closely allied 

zur Biologic der Orchidecn,' 1853, to, and even perhaps a monstro- 

pp. 78 and 42) description of the sity of, Cypripedium, a third fer- 

development of the flower-bud of tile anther occupies this same 

Cypripedium, it would appear that position, 
there is a tendency to the forma- 



CuAi. VIII FLOWERS OF ORCHIDS. 241 

of Malaxis paludosa, the close resemblance between the 
two membranes of the clinandrum and the fertile 
anther, in shape, texture, and in the height to which 
the spiral vessels extended, was most striking : it was 
impossible to doubt that in these two membranes we 
had two rudimentary anthers. In Evelyna, one of the 
Epidendrese, the clinandrum was similarly formed, as 
were the horns of the clinandrum in Masdevallia, which 
serve in addition to keep the labellum at the proper 
distance from the column. In Liparis petidula and 
some other species, these two rudimentary anthers form 
not only the clinandrum, but likewise wings, which 
project on each side of the entrance into the stigmatic 
cavity, and serve as guides for the insertion of the 
pollen-masses. In Acropera and Stanhopea, as far as 
I could make out, the membranous borders of the 
column, down to its base, were also thus formed ; but 
in other cases, as in Cattleya, the wing-like borders of 
the column seem to be simple developments of the two 
pistils. In this latter genus, as well as in Catasetum, 
these same two rudimentary stamens, judging from the 
position of the vessels, serve chiefly to strengthen 
the back of the column ; and the strengthening of the 
front of the column is the sole function of the third 
stamen of the inner whorl (ag), in those cases in 
which it was observed. This third stamen runs up 
the middle of the column to the lower edge, or lip, 
of the stigmatic cavity. 

I have said that in the OphreaB and JSTeottese the 
spiral vessels of the inner whorl, marked a^, a^, a^ in 
the diagram, are entirely absent, and I looked care- 
fully for them ; but in nearly all the members of these 
two tribes, two small papillae, or auricles as they have 
been often called, stand in exactly the position which 
the two first of these three anthers would have occupied, 



242 HOMOLOGIES OF THE Chap. VIII. 

had they been developed. Not only do they stand in 
this position, but the column in some cases, as in 
Ceplialanthera, has on each side a prominent ridge, 
running from them to the bases or mid-ribs of the two 
upper petals ; that is, in the proper position of the 
filaments of these two stamens. It is, again, impossible 
to doubt that the two membranes of the clinandrum 
in Malaxis are formed by these two anthers in a 
rudimentary and modified condition. Now, from the 
perfect clinandrum of Malaxis, through that of Spi- 
ranthes, Goodyera, EpipacHs latifolia, and E. palustris 
(see fig. 16, p. 101, and fig. 15, p. 94), to the minute 
and slightly flattened auricles in the genus Orchis, a 
perfect gradation can be traced. Hence I conclude that 
these auricles are doubly rudimentary ; that is they 
are rudiments of the membranous sides of the clinan- 
drum, these membranes themselves being rudiments of 
the two anthers so often referred to. The absence of 
spiral vessels running to the auricles is by no means 
sufficient to overthrow the views here advocated as to 
the much disputed nature of these structures; that 
such vessels may quite disappear, we have proof in 
Ceplialanthera grandiJio7'a, in which the rostellum and 
its vessels are completely aborted. 

Finally, then, with respect to the six stamens which 
ought to be represented in every Orchid: the three 
belonging to the outer whorl are always present, the 
upper one being fertile (except in Cypripedium), and 
the two lower ones invariably petaloid and forming 
part of the labellum. The three stamens of the inner 
whorl are less plainly developed, especially the lower 
one, a^, which, when it can be detected, serves only to 
strengthen the column, and, in some rare cases, accord- 
ing to Brown, forms a separate projection or filament ; 
the two upper anthers of this inner whorl are fertile 



Chap. VIII. FLOWERS OF ORCHIDS. 243 

ill Cypripedium, and in other cases are generally 
represented either by membranous expansions, or by 
minute auricles without spiral vessels. These auricles, 
however, are sometimes quite absent, as in some species 
of Ophrys. 

On this view of the homologies of Orchid-flowers, 
we can understand the existence of the conspicuous 
central column, — the large size, generally tripartite 
form, and peculiar manner of attachment of the la- 
bellum, — the origin of the clinandrum, — the relative 
position of the single fertile anther in most of the 
genera, and of the two fertile anthers in Cypripedium, 
— the position of the rostellum, as well as of all the 
other organs, — and lastly, the frequent occurrence of a 
bilobed stigma, and the occasional occurrence of two 
distinct stigmas. I have encountered only one case oi 
dijQficulty, namely in Habenaria and the allied genus, 
Bonatea. These flowers have undergone such an 
extraordinary amount of distortion, owing to the wide 
separation of their anther-cells and of the two viscid 
discs of the rostellum, that any anomaly in them is 
the less surprising. The anomaly relates only to the 
vessels supplying the sides of the upper sepal and 
of the two upper petals ; for the vessels running into 
their midribs and into all the other more important 
organs pursue the same identical course as in the other 
Ophrese. The vessels which supply the sides of the 
upper sepal, instead of uniting with the midrib and 
entering the posterior ovarian group, diverge and enter 
the postero-lateral groups. Again, the vessels on the 
anterior side of the two upper petals, instead of uniting 
with those of the midrib and entering the postero- 
lateral ovarian groups, diverge, or wander from their 
proper course, and enter the antero-lateral groups. 

This auomaly is so far of iuiportance, as it throws 



244 HOMOLOGIES OF THE Chap. VIII. 

some doubt on the view tliat tlie labellum is always 
an organ compounded of one petal and two petaloid 
stamens ; for if any one were to assume that from some 
unknown cause the lateral vessels of the lower petals 
had diverged in an early progenitor of the Orchidean 
order from their proper course into the antero-lateral 
ovarian groups, and that this structure had been in- 
herited by all existing Orchids, even by those with the 
smallest and simplest labellums, I could answer only 
as follows ; but the answer is, I think, satisfactory. 
From the analogy of other monocotyledonous plants, 
we might expect the hidden presence of fifteen organs 
in the flowers of the Orchidea?, arranged alternately 
in five whorls; and in these flowers we find fifteen 
groups of vessels exactly thus arranged. Hence thei e 
is a strong probability that the vessels, A2 and A3, 
which enter the sides of the labellum, not in one or 
two cases, but in all the Orchids seen by me, and which 
occupy the precise position which they would have 
occupied had they supplied two normal stamens, do 
really represent modified and petaloid stamens, and 
are not lateral vessels of the labellum which have 
wandered from their proper course. In Habenaria and 
Bonatea,* on the other hand, the vessels proceeding 



* In Bonatea speciosa, of which ments of the two upper petals 

I have exauiined only dry speci- coh<re with the labellum, causing 

mens sent me by Dr. Hooker, the it to have five segments, which is 

vessels from the sides of the upper a most imusual feet. Tiie two 

sepal enter the postero-lateial wonderfully protuberant stigmas 

ovarian group, exactly as in also cohere to the upper surface of 

Habenaria. The two upper petals the labellum ; and the lower sepals 

are divided down to their bases, apparently also cohere to its under 

and the vessels supplying the side. Consequently a section of 

anterior segment and those supply- the base of the labellum divides 

ing the anterior portion of the one lower petal, two petaloid 

posterior segment unite and then anthers, porticns of the two upper 

run, as in Habenaria, into the petals, and apparently of the two 

antero-latiral (and therefore lower sepals and the two stigmas : 

wrong) group. The anterior seg- altogether the section passes 



Chap. VIII. FLOWEKS OF OECHIDS. 245 

from the sides of the upper sepal and of the two upper 
petals, which enter the wrong ovarian groups, cannot 
possibly represent any lost but once distinct organs. 

We have now finished with the general homologies 
of the flowers of Orchids. It is interesting to look at 
one of the magnificent exotic species, or, indeed, at 
one of our humblest forms, and observe how profoundly 
it has been modified, as compared with all ordinary 
flowers, — with its great labellum, formed of one petal 
and two petaloid stamens, — with its singular pollen- 
masses, hereafter to be referred to, — with its column 
formed of seven cohering organs, of which three alone 
perform their proper function, namely, one anther and 
two generally confluent stigmas, — with the third stigma 
modified into the rostellum and incapable of being 
fertilised, — and with three of the anthers no longer 
functionally active, but serving either to protect the 
pollen of the fertile anther, or to strengthen the column, 
or existing as mere rudiments, or entirely suppressed. 
What an amount of modification, cohesion, abortion, 
and change of function do we here see ! Yet hidden 
in that column, with its surrounding petals and sepals, 
we know that there are fifteen groups of vessels, 
arranged three within three, in alternate order, which 
probably have been preserved to the present time from 
being developed at a very early period of growth, 
before the shape or existence of any part of the flower 
is of importance for the well-being of the plant. 

Can we feel satisfied by saying that each Orchid was 
created, exactly as we now see it, on a certain " ideal 
type ; " that the omnipotent Creator, having fixed on 
one plan for the whole Order, did not depart from this 

throngli the whole of or through is licreas comiilex anoriran as the 
portions of cither seven or nine column of other Orchids, 
organs. The l)ase of tlie labellum 



246 HOMOLOGIES. Chap. VIIL 

plan ; that he, therefore, made the same organ to per- 
form diverse functions — often of trifling importance 
compared with their proper function — converted other 
organs into mere purposeless rudiments, and arranged 
all as if they had to stand separate, and then made 
them cohere ? Is it not a more simple and intelligible 
view that all the Orchidese owe what they have in 
common, to descent from some monocotyledonous 
plant, which, like so many other plants of the same 
class, possessed fifteen organs, arranged alternately 
three within three in five whorls ; and that the now 
wonderfully changed structure of the flower is due to 
a long course of slow modification, — each modification 
having been preserved which was useful to the plant, 
during the incessant changes to which the organic 
and inorganic world has been exposed ? 



CHAr. IX. GRADATION OF OEGANS. 247 



CHAPTER IX. 

GRADATION OF ORGANS, &C. — CONCLUDING REMARKS. 

Gradation of organs, of the rostelhim, of the pollen-masses — Formation 
of the caudicle— Genealogical affinities — Secretion of nectar^ 
Mechanism of the movement of the pollinia — Uses of the petals — 
Production of seed — Importance of trifling details of structure — 
Cause of the great diversity of structure in the flowers of Orchids 
— Cause of the perfection of the contrivances — Summary on insect- 
agency — Nature abhors perpetual self-fertilisation. 

This chapter will be devoted to the consideration of 
several miscellaneous subjects which could not well 
have been introduced elsewhere. 

On the gradation of certain Organs. — The rostellum, 
the pollinia, the labellum, and, in a lesser degree, 
the column, are the most remarkable points in the 
structure of Orchids. The formation of the column 
and labellum, by the confluence and partial abortion of 
several organs, has been discussed in the last chapter. 
With respect to the rostellum, no such organ exists 
in any other group of plants. If the homologies of 
Orchids had not been pretty well made out, those 
who believe in the separate creation of each organism 
might have advanced this as an excellent instance of 
a perfectly new organ having been specially created, 
and which could not have been developed by suc- 
cessive slow modifications of any pre-existing part. 
But, as Robert Brown long ago remarked, it is not a 
new organ. It is impossible to look at the two groups 
of spiral vessels (fig. 36) running from the bases of 



248 GRADATION OF ORGANS. Chap. IX. 

the midribs of the two lower sepals to the two lower 
stigmas, which are sometimes quite distinct, and then 
to look at the third group of vessels running from the 
base of the mid-rib of the upper sepal to the rostellum, 
which occupies the exact position of a third stigma, 
and doubt its homological nature. There is every 
reason to believe that the whole of this upper stigma, 
and not merely a part, has been converted into the 
rostellum ; for there are plenty of cases of two stigmas, 
but not one of three stigmatic surfaces being present 
in those Orchids which have a rostellum. On the 
other hand, in Cypripedium and Apostasia (the latter 
ranked by Brown in the Orchidean order), which are 
destitute of a rostellum, the stigmatic surface is trifid. 
As we know only those plants which are now living, 
it is impossible to follow all the gradations by which 
the upper stigma has been converted into the rostellum ; 
but let us see what are the indications of such a change 
having been effected. With respect to function the 
change has not been so great as it at first appears. 
The function of the rostellum is to secrete viscid matter, 
and it has lost the capacity of being penetrated by 
the pollen-tubes. The stigmas of Orchids, as well as 
of most other plants, secrete viscid matter, the use of 
which is to retain the pollen when brought to them by 
any means, and to excite the growth of the pollen- 
tubes. Now if we look to one of the simplest rostel- 
lums, — for instance, to that of Cattleya or Epidendrum, 
— we find a thick layer of viscid matter, not distinctly 
separated from the viscid surface of the two confluent 
stigmas : its use is simply to affix the pollen-masses to 
a retreating insect, which are thus dragged out of the 
anther and transported to another flower, where they 
are retained by the almost equally viscid stigmatic 
surface. So that the oflice of the rostellum is still to 



Chap. IX. GKADATION OF ORGANS. 249 

secure the pollen-masses, but indirectly by means of 
their attachment to an insect's body. 

The viscid matter of the rostellum and of the 
stigma appear to have nearly the same nature ; that 
of the rostellum generally has the peculiar property of 
quickly drying or setting hard ; that of the stigma, 
when removed from the plant, apparently dries more 
quickly than gum-water of about equal density or 
tenacity. This tendency to dry is the more remarkable, 
as Gartner * found that drops of the stigmatic secre- 
tion from Nicotiana did not dry in two months. The 
viscid matter of the rostellum in many Orchids when 
exposed to the air changes colour with remarkable 
quickness, and becomes brownish-purple ; and I have 
noticed a similar but slower change of colour in the 
viscid secretion of the stigmas of some Orchids, as of 
Cephalanthera grandiflora. When the viscid disc of an 
Orchis, as Bauer and Brown have observed, is placed 
in water, minute particles are expelled with violence 
in a peculiar manner ; and I have observed exactly 
the same fact in the layer of viscid matter covering 
the stigmatic utriculi in an unopened flower of Mor- 
modes ignea. 

In order to compare the minute structure of the 
rostellum and stigma, I examined young flower-buds 
of Epidendrum cochleatum and floribundum, which, when 
mature, have a simple rostellum. The posterior parts 
of both organs were quite similar. The whole of 
the rostellum at this early age consisted of a mass 
of nearly orbicular cells, containing spheres of brown 
matter, which resolve themselves into the viscid fluid. 
Tlie stigma was covered with a thinner layer of similar 
cells, and beneath them were the coherent spindle- 



Beitrajjo 7iir Kenutniss der Befruclitung,' 1844, p. 236. 
12 



250 GRADATION OF OKGANS. Chap. IX. 

formed utriculi. These are believed to be connected 
with the penetration of the pollen-tubes ; and their 
absence in the rostellum probably accounts for its 
not being penetrated. If the structure of the ros- 
tellum and of the stigma is as here described, their 
only difference consists in the layer of cells which 
secrete the viscid matter being thicker in the ros- 
tellum than in the stigma, and in the utriculi having 
disappeared from the former. There is therefore no 
great difficulty in believing that the upper stigma, 
whilst still in some degree fertile or capable of pene- 
tration by the pollen-tubes, might have gradually 
acquired the power of secreting a larger amount of 
viscid matter, losing at the same time its capacity for 
fertilisation ; and that insects smeared with this viscid 
matter removed and transported the pollen-masses in 
a more and more effective manner to the stigmas of 
other flowers. In this case an incipient rostellum 
would have been formed. 

In the several tribes, the rostellum presents a 
marvellous amount of diversity of structure ; but most 
of the differences can be connected without very wide 
breaks. One of the most striking differences is, that 
either the whole anterior surface to some depth, or 
only the internal parts become viscid ; and in this 
latter case the surface retains, as in Orchis, a mem- 
branous condition. But these two states graduate 
into each other so closely, that it is scarcely possible 
to draw any line of separation between them : thus, 
in Epipactis, the exterior surface undergoes a vast 
change from its early cellular condition, for it becomes 
converted into a highly elastic and tender membrane, 
which is in itself slightly viscid, and allows the under- 
lying viscid matter readily to exude ; yet it acts as a 
membrane, and its under surfac^^ is lined with much 



CuAP. IX. GRADATION OF ORGANS. 251 

more viscid matter. In Hahenaria clilorantJia the 
exterior surface is highly viscid, but still closely re- 
sembles, under the microscope, the exterior membrane 
of Epipactis. Lastly, in some species of Oncidium, 
&c., the exterior surface, which is viscid, differs, as far 
as appearance under the microscope goes, from the 
underlying viscid layer only in colour; but it must 
have some essential difference, for I find that, until 
this very thin exterior layer is disturbed, the under- 
lying matter remains viscid ; but, after it has been 
disturbed, the underlying matter rax3idly sets hard. 
The gradation in the state of the surface of the ros- 
tellum is not surprising, for in all cases the surface is 
cellular in the bud ; so that an early condition has 
only to be retained more or less perfectly. 

The nature of the viscid matter dift'ers remarkably 
in different Orchids : in Listera it sets hard almost 
instantly, more quickly than plaster of Paris ; in 
]\Ialaxis and Angrascum it remains fluid for several 
days ; but these two states pass into each other by 
many gradations. In an Oncidium I have observed 
the viscid matter to dry in a minute and a half; in 
some species of Orchis in two or three minutes ; in 
Epipactis in ten minutes; in Gymnadenia in two 
hours ; and in Habenaria in over twenty-four hours. 
After the viscid matter of Listera has set hard, neither 
water nor weak spirits of wine has any effect on it ; 
whereas that of Habenaria hifolia, after having been 
dried for several months, when moistened became as 
adhesive as ever it was. The viscid matter in some 
species of Orchis, when remoistened, presented an 
intermediate condition. 

One of the most important differences in the state 
of the rostellum is, whether or not the pollinia are 
permanently attached to it. I do not alhulo to those 



252 GRADATION OF ORGANS. Cuap. IX. 

cases in which the upper surface of the rostellum is 
viscid, as in Malaxis and some Epidendrums, and 
simply adheres to the pollen-masses; for these cases 
present no difficulty. But I refer to the so-called con- 
genital attachment of the pollinia by their caudicles 
to the rostellum or viscid disc. It is not, however, 
strictly correct to speak of congenital attachment, for 
the pollinia are invariably free at an early period, and 
become attached either earlier or later in different 
Orchids. No actual gradation is at present known in 
the process of attachment ; but it can be shown to 
depend on very simple conditions and changes. In 
the Epidendreae the pollinia consist of a ball of waxy 
pollen, with a long caudicle (formed of elastic threads 
with adherent pollen-grains), which never becomes 
spontaneously attached to the rostellum. In some of 
the Vandese, as in Gymhidium giganteum, on the other 
hand, the caudicles are congenitally (in the above 
sense) attached to the pollen-masses, but their struc- 
ture is the same as in the Epidendrese, with the sole 
difference, that the extremities of the elastic threads 
adhere to, instead of merely lying on, the upper lip of 
the rostellum. 

In a form allied to Cymbidium, namely, Oncidium 
unguic'ulatiim, I studied the development of the cau- 
dicles. At an early period the pollen-masses are 
enclosed in membranous cases, which soon rupture at 
one point. At this early period, a layer of rather 
large cells, including remarkably opaque matter, may 
be detected within the cleft of each pollen-mass. Tiiis 
matter can be traced as it gradually changes into a 
translucent substance which forms the threads of the 
caudicles. As the change progresses, the cells them- 
selves disappear. Finally the threads at one end ad- 
here to the waxy pollen-masses, and at the other end 



Chap. IX. GRADATION OF ORGANS. 253 

after protruding through a small opening in the mem- 
branous case in a semi-developed state, they adhere 
to the rostellum, against which the anther is pressed. 
So that the adhesion of the caudicle to the back of the 
rostellum seems to depend solely on the early rupturing 
of the anther-case, and on a slight protrusion of the 
caudicles, before they have become fully developed and 
hardened. 

In all the Orchideoe a portion of the rostellum is 
removed by insects when the pollinia are removed ; for 
the viscid matter, though conveniently spoken of as a 
secretion, is in fact part of the rostellum in a modified 
condition. But in those species which have their 
caudicles attached at an early period to the rostellum, 
a membranous or solid portion of its exterior surface in 
an unmodified condition is likewise removed. In the 
Vandeae this portion is sometimes of considerable size 
(forming the disc and pedicel of the pollinium), and 
gives to their pollinia their remarkable character ; but 
the differences in the shape and size of the removed 
portions of the rostellum can be finely graduated to- 
gether, even within the single tribe of the Yandeae ; 
and still more closely by commencing with the minute 
oval atom of membrane to which the caudicle of Orchis 
adheres, passing thence to that of Hahenaria hifolia, to 
that of H. cJilorantha with its drum -like pedicel, and 
thence through many forms to the great disc and 
pedicel of Catasetum. 

In all the cases in which a portion of the exterior 
surface of the rostellum is removed together with the 
caudicles of the pollen-masses, definite and often com- 
plicated lines of separation are formed, so as to allow 
of the easy separation of the removed portions. But 
the formation of these lines of separation does not 
differ much from the process by which certain portions 



254 GKADATION OF ORGANS. Chap. IX. 

of the exterior surface of the rostellum assume a con- 
dition intermediate between that of unaltered mem- 
brane and of viscid matter, which has been already 
alluded to. The actual separation of portions of the 
rostellum depends in many cases on the excitement 
from a touch ; but how a touch thus acts is at present 
inexplicable. Such sensitiveness in the stigma to a 
touch (and the rostellum, as we know, is a modified 
stigma), and indeed in almost every other part, is by 
no means a rare quality in plants. 

In Listera and Neottea, if the rostellum is touched, 
even by a human hair, two points rupture and the 
loculi containing the viscid matter instantly expel it. 
Here we have a case towards which as yet no gradation 
is known. But Dr. Hooker has shown that the ros- 
tellum is at first cellular, and that the viscid matter 
is developed within the cells, as in other Orchids. 

The last difference which I will mention in the 
state of the rostellum of various Orchids is the exist- 
ence in many Ophrese of two widely-separated viscid 
discs, sometimes included in two separate pouches. 
Here it appears at first sight as if there were two 
rostella ; but there is never more than one medial 
group of spiral vessels. In the Vanclese we can see 
how a single viscid disc and a single pedicel might 
become divided into two ; for in some Stanhopeas the 
heart-shaped disc shows a trace of a tendency to divi- 
sion; and in Angrsecum we have two distinct discs 
and two pedicels, either standing close together or 
removed only a little way apart. 

It might be thought that a similar gradation from a 
single rostellum into what appears like two distinct ros- 
tella was shown still more plainly in the Ophrese ; for 
we have the following series, — in Orchis injramidalis a 
single disc enclosed in a single pouch — in Aceras two 



Chap. IX. GEADATION OF ORGANS. 255 

discs touching and affecting each other's shapes, but 
not actually joined — in Orchis latifolia and maculata 
two quite distinct discs but with the pouch still 
showing plain traces of division; and, lastly, in 
Ophrys we have two perfectly distinct pouches, in- 
cluding of course two perfectly distinct discs. Bu^ 
this series does not indicate the former steps by whic? 
a single rostellum became divided into two distinct 
organs ; on the contrary, it shows how the rostel 
lum, after having been anciently divided into two 
organs, has now in several cases been reunited into 
a single organ. 

This conclusion is founded on the nature of the little 
medial crest, sometimes called the rostellate process, 
between the bases of the two anther-cells (see fig. 1, 
B and D, p. 8). In both divisions of the Ophrese — 
namely the species having naked discs and those 
having discs enclosed in a pouch — whenever the two 
discs come into close juxta-position, this medial crest 
or process appears.* On the other hand, when the two 
discs stand widely apart, the summit of the rostellum 
between them is smooth, or nearly smooth. In the 
Frog Orchis {Peristylus viridis) the overarching sum- 
mit is bent like the roof of a house ; and here we see 
the first stage in the formation of the folded crest. In 
Herminium monorchis, however, which has two separate 
and large discs, a crest, or solid ridge, is rather more 
plainly developed than might have been expected. 
In Gijmnadenia eonopsea, Orchis macidata, and others, 
the crest consists of a hood of thin membrane ; in 



* Professor Babingtou ('Manual from the other genera of Ophreaj. 

of British Botany,' 3rd edit.) uses The group of spiral vessels, pro- 

the existence of this "rostellate perly helonging to the rostellum, 

process " as a chiiracter to separate runs up, aud even into, the base 

Orchis, (iymnadcuia, and Aceras of this crest or process. 



256 GEADATION OF ORGANS. Chap. IX. 

0. mascula the two sides of the hood partly adhere ; 
and in 0. j^yramidalis and in Aceras it is converted 
into a solid ridge. These facts are intelligible only 
on the view, that, whilst the two discs were gradually 
brought together, during a long series of generations, 
the intermediate portion or summit of the rostellum 
became more and more arched, until a folded crest, 
and finally a solid ridge was formed. 





Rostellum of CATASETUia. 

an. antennas of rostellum. I ped. pedicel of rostellum, to which 

d. viscid disc. I the pollen-masses are attached. 

Whether we compare together the state of the ros- 
tellum in the various tribes of the Orchidese, or com- 
pare the rostellum with the pistil and stigma of an 
ordinary flower, the differences are wonderfully great. 
A simple pistil consists of a cylinder surmounted by 
a small viscid surface. Now, see what a contrast the 
rostellum of Catasetum, when dissected from all the 
other elements of the column, presents ; and as I 
traced all the vessels in this Orchid, the drawing may 
b(^ trusted as approximately accurate. The whole organ 



Ohap. JX. gradation OF ORGANS. 257 

has lost its normal function of being fertilised. Its 
shape is most singular, with the upper end thickened, 
bent over and produced into two long tapering and 
sensitive antennae, each of these being hollow within, 
like an adder's fang. Behind and between the bases 
of these antennae we see the large viscid disc, attached 
to the pedicel ; the latter differs in structure from the 
underlying portion of the rostellum, and is separated 
from it by a layer of hyaline tissue, which spontaneously 
dissolves when the flower is mature. The disc, attached 
to the surrounding parts by a membrane which ruptures 
as soon as it is excited by a touch, consists of strong 
upper tissue, with an underlying elastic cushion, 
coated with viscid matter; and this again in most 
Orchids is overlaid by a film of a differeiifc nature. 
What an amount of specialisation of paifcs do we 
here behold ! Yet in the comparatively few Orchids 
described in this volume, so many and such plainly- 
marked gradations in the structure of the rostellum 
have been described, and such plain facilities for the 
conversion of the upper pistil into this organ, that, we 
may well believe, if we could see every Orchid which 
has ever existed throughout the world, we should find 
all the gaps in the existing chain, and every gap in 
in many lost chains, filled up by a series of easy 
transitions. 

We now come to the second great peculiarity in the 
Orchideae, namely their pollinia. The anther opens 
early, and often deposits the naked masses of pollen on 
the back of the rostellum. This action is prefigured 
in Canna, a member of a family nearly related to the 
Orchideae, in which the pollen is deposited on the pistil, 
close beneath the stigma. In the state of the pollen 
there is great diversity : in Cypripedium and Vanilla 



258 GRADATION OF ORGANS. Chap. IX 

single grains are embedded in a glutinous fluid ; in 
all the other Orchids seen by me (except the degraded 
Oephalanthera) the grains are united three or four 
together.* These compound grains are tied one to 
the other by elastic threads, but they often form 
packets which are tied together in like manner, or 
they are cemented into the so-called waxy masses. 
The waxy masses graduate in the Epidendreae and 
Vandese from eight to four, to two, and, by the co- 
hesion of the two, into a single mass. In some of the 
Epidendrese we have both kinds of pollen within the 
same anther, namely, large waxy masses, and caudicles 
formed of elastic threads with numerous compound 
grains adhering to them. 

I can throw no light on the nature of the cohesion 
of the pollen in the waxy masses ; when they are 
placed in water for three or four days, the compound 
grains readily fall apart ; but the four grains of which 
each is formed still firmly cohere ; so that the nature 
of the cohesion in the two cases must be different. 
1'he elastic threads by which the packets of pollen are 

* In several cases I have ob- tubes are, at least at first, formed 

served four tubes emitted fiom exclusively at the expense of the 

the four giains which form one of contents of the pollen -grains, 

the compound grains. In some Having alluded to the monstrous 

senii-m.onsttous flowers of Ma/aa-/.s flowers of the Aceias, I will add 

paludosa, and of Aceras anthropo- thai I examined several (always 

phora, and in perfect flowers of the lowest on the spike) in which 

JSeottia nidus-avis, i have observed the labellum was hardly developed, 

tubes emitted from the pollen- and w^as pressed close agninst the 

grains, whils^t still within the stigma. The mstellum was not 

anther and not m contact with developed, so that the polliida did 

the fctigma. I have thought this not possess viscid discs ; but the 

worth mentioning as R. Brown most curious feature was, that the 

(' Linn. Transact.' vol. xvi. p. 729) two anther-cells had become, appa- 

states, apparently with some sur- rently in consequence of the post- 

prise, that the pollen-tubes wt re tion of the rudimentary labellum. 

eniitted from the pollen, whilst widely separated, and were joined 

Htill within the anther, in a decay- by a connective membrane, almost 

ing flower of Asclcpias. These as broad as that of Haheiiaria 

tases show that the protruding ddoraiitha J 



Chap. IX. GRADATION OF ORGANS. 259 

tied together in the Ophreae, and which run far up 
inside the waxy masses of the Vandeae, are also of a 
different nature from the cementing matter ; for the 
threads are acted on by chloroform and by long im- 
mersion in spirits of wine ; whilst these fluids have no 
particular action on the cohesion of the waxy masses. 
In several EpidendresB and Yandeae the exterior grains 
of the pollen-masses difter from the interior grains, in 
being larger, and in having yellower and much thickei 
walls. So that in the contents of a single anther-cell 
we see a surprising degree of differentiation in the 
pollen, namely, grains cohering by fours, then being 
either tied together by threads or cemented together 
into solid masses, with the exterior grains different 
from the interior ones. 

In the Vandeae, the caudicle, which is composed of 
fine coherent threads, is developed from the semi-fluid 
contents of a layer of cells. As I find that chloroform 
has a peculiar and energetic action on the caudicles 
of all Orchids, and likewise on the glutinous matter 
which envelopes the pollen-grains in Cypripedium, 
and which can be drawn out into threads, we may 
suspect that in this latter genus, — the least differenti- 
ated in structure of all the Orchideae, — we see the 
primordial condition of the elastic threads by which 
the pollen-grains are tied together in other and more 
highly developed species.* 



* Auguste de Saint Hilairc drop by drop into the anther. 

('Lemons de Botaniqne,' &c.. 1841, Had not so eminent an authority 

p. 447) says that the elastic threads made this statement, I should not 

exist in the early bud, after the have noticed it. It is ccrtiiinlv 

jjoUen-grains hiive been partly erroneous. In buds of Epipactis 

formed, as a thick creamy fluid. latifoUa I opened the Muther, 

He adds tliat his observations on whilst perftctly clos; d and free 

Ophrys apifera have shown him from ihe rostelluin, and found the 

that this fluid is secreted by the pollen-grains united by elastic 

robtellum, and is slowly forced threads. Ccvhalajithcrn <jrandi' 



260 GRADATION OF ORGANS. Chap. IX 

The caudicle, when largely developed and destitute 
of pollen-grains, is the most striking of the many pecu- 
liarities presented by the pollinia. In some Neottese, 
especially in G-oodyera, we see it in a nascent con- 
dition, projecting just beyond the pollen-mass, with 
the threads only partially coherent. In the Yandese 
by tracing the gradation from the ordinary naked 
condition of the caudicle, through Lycaste in which 
it is almost naked, through Calanthe, to Gymhidium 
giganteum, in which it is covered with pollen-grains, it 
seems probable that its ordinary condition has been 
arrived at by the modification of a pollinium like 
that of one of the Epidendreae ; namely, by the abor- 
tion of the pollen-grains which primordially adhered to 
separate elastic threads, and afterwards by the cohesion 
of these threads. 

In the Ophreae we have better evidence than is 
afforded by gradation, that their long, rigid and 
naked caudicles have been developed, at least partially, 
by the abortion of the greater number of the lower 
pollen-grains and by the cohesion of the elastic threads 
by which these grains were tied together. I had often 
observed a cloudy appearance in the middle of the 
translucent caudicles in certain species ; and on care- 
fully opening several caudicles of Orchis pyramidalis, 
i found in their centres, fully half-way down between 
the packets of pollen and the viscid disc, many pollen- 
grains (consisting, as usual, of four united grains). 



Aora hns no rostellum to secrete and stigma ; yet I found in one 

the above thick fluid, yet the of thse auricles a distinct caudicle 

pollen-grains are thus united. In (which necessarily had no disc at 

a monstrous specimen of Orchis its extremity), and this caudicle 

pyramidalis the auricles, or nidi- could not possibly have been 

mentary anthers on eacli side of secreted by the rostellum oi 

the proper anther, hnd become stigma. I could advance addi 

partly developed, and they stood tiomil evidence, but it would be 

quile on one side of the robtellum su[)erfluoud. 



CuAP. IX GRADATION OF OEGANS. 261 

lying quite loose. These grains, from their embedded 
position, could never by any possibility have been left 
on the stigma of a flower, and were absolutely useless. 
Those who can persuade themselves that purposeless 
organs have been specially created, will think little of 
this fact. Those on the contrary, who believe in the 
slow modification of organic beings, will feel no 
surprise that the changes have not always been per- 
fectly effected, — that, during and after the many 
inherited stages of the abortion of the lower pollen- 
grains and of the cohesion of the elastic threads, 
there should still exist a tendency to the production 
of a few grains where they were originally developed ; 
and that these should consequently be left entangled 
within the now united threads of the caudicle. They 
will look at the little clouds formed by the loose 
pollen-grains within the caudicles of Orchis pjramidalis, 
as good evidence that an early progenitor of this plant 
had pollen-masses like those of Epipactis or Goodyera, 
and that the grains slowly disappeared from the lower 
parts, leaving the elastic threads naked and ready to 
cohere into a true caudicle. 

As the caudicle plays an important part in the 
fertilisation of the flower, it might have been deve- 
loped from one in a nascent condition, such as we see 
in Epipactis, to any required length merely by the 
continued preservation of varying increments in its 
length, each beneficial in relation to other changes in 
the structure of the flower, and without any abortion 
of the lower pollen-grains. But we may conclude 
from the facts just given, that this has not been the 
sole means, — that the caudicle owes much of its length 
to such abortion. That in some cases it has subse- 
quently been largely increased in length by natural 
selection, is highly probable; for in Bonatea sj^eciosa 



262 LINES OF DESCENT. Chap. IX. 

the caudicle is actually more than thrice as long as the 
elongated pollen-masses ; and it is highly improbable 
that so lengthy a mass of grains, slightly cohering 
together by the aid of elastic threads, should ever have 
existed, as an insect could not have safely transported 
and applied a mass of this shape and size to the 
stigma of another flower. 

We have hitherto considered gradations in the state 
of the same organ. To any one with more knowledge 
than I possess, it would be an interesting subject to 
trace the gradations between the several species and 
groups of species in this great and closely-connected 
order. But to make a perfect gradation, all the extinct 
forms which have ever existed, along many lines of 
descent converging to the common progenitor of the 
group, would have to be called back into life. It is 
due to their absence, and to the consequent wide gaps 
in the series, that we are enabled to divide the exist- 
ing species into definable groups, such as genera, 
families, and tribes. If there had been no extinction, 
there would still have been great lines or branches of 
special development, — the Vandese, for instance, would 
still have been distinguishable as a great body, from 
the great body of the Ophrese ; but ancient and inter- 
mediate forms, very different probably from their 
present descendants, would have rendered it utterly 
impossible to separate by distinct characters the one 
great body from the other. 

I will venture on only a few more remarks. Cypri- 
pedium, in having three stigmas developed, and there- 
fore in not possessing a rostellum, in having two fertile 
anthers with a large rudiment of a third, and in the 
state of its pollen, seems a remnant of the order whilst 
in a simpler or more generalised condition. Apostasia 



Chap. IX. LINES OF DESCENT. 263 

is a related genus, placed by Brown amongst the 
Orchideae, but by Lindley in a small distinct family. 
These broken groups do not indicate to us the structure 
of the common parent-form of all the Orchidese, but 
they serve to show the probable state of the order in 
ancient times, when none of the forms had become so 
widely differentiated from one another and from other 
plants, as are the existing Orchids, especially the 
Yandese and Ophrcfe ; and when, consequently, the 
order made a nearer approach in all its characters, 
than it does at present, to such allied groups as the 
Marantaceae. 

With respect to other Orchids, we can see that an 
ancient form, like one of the sub-tribe of the Pleuro- 
thallidae, some of which have waxy pollen-masses with 
a minute caudicle, might have given rise, by the entire 
abortion of the caudicle, to the Dendrobise, and by an 
increase of the caudicle to the Epidendrefe. Cymbi- 
dium shows us how simply a form like one of our 
present Epidendrese could be modified into one of the 
Vandese. The Neottese stand in nearly a similar relation 
to the higher Ophreae, which the Epidendrefe do to the 
higher Vandese. In certain genera of the Neotteae we 
have eompound pollen-grains cemented into packets 
and tied together by elastic threads, which project and 
thus form a nascent caudicle. But this caudicle does 
not protude from the lower end of the pollinium as in 
the OphresB, nor does it always protrude from the ex- 
treme upper end in the Neottese, but sometimes at an 
intermediate level ; so that a transition in this respect 
is far from impossible. In Spiranthes, the back of the 
rostellum, lined with viscid matter, is alone removed : 
the front part is membranous, and ruptures like the 
pouch-formed rostellum of the Ophreae. An ancient 
form combining most of the characters, but in a less 



264 LINES OF DESCENT. Chap. IX. 

developed state, of Goodyera, Epipactis, and Spiranthes, 
all members of the Neottese, could by further slight 
modifications have given birth to the tribe of the 
Ophreae. 

Hardly any question in Natural History is more 
vague and diflicult to answer than what forms ought 
to be considered as the highest in a large group ; * for 
all are well adapted to their conditions of life. If we 
look to successive modifications, with difi'erentiation of 
parts and consequent complexity of structure, as the 
standard of comparison, the Ophreae and Yandese will 
stand the highest among the Orchidea3. Are we to lay 
much stress on the size and beauty of the flower, and 
on the size of the whole plant ? if so, the Yandeae are 
pre-eminent. They have, also, rather more complex 
poUinia, with the pollen-masses often reduced to two. 
The rostellum, on the other hand, has apparently been 
more modified from its primordial stigmatic nature in 
the Ophreae, than in the Yandeae. In the Ophreae the 
stamens of the inner whorl are almost entirely sup- 
pressed, — the auricles — mere rudiments of rudiments — 
being alone retained; and even these are sometimes 
lost. These stamens, therefore, have suffered extreme 
reduction; but can this be considered as a sign of 
highness? I should doubt whether any member of 
the Orchidean order has been more profoundly modified 
in its whole structure than Bonatea specicsay one of the 
Ophreae. So again, within this same tribe, nothing 
can be more perfect than the contrivances in Orchis 
pyramidalis for its fertilisation. Yet an ill -defined 
feeling tells me to rank the magnificent Yandeae as 
the highest. When we look within this tribe at the 



* The fullest and the most able his * Eiitwickelungs-Gesotze der 
discussion un this ditiiculr, subject Organischen Welt/ 1S58. 
'a by Pioiesbor 11. G. Bionn in 



Chap. IX SECEETION OF NECTAR. 265 

elaborate mechanism for the ejection and transportal 
of the pollinia of Catasetum, with the sensitive ros- 
tellum so wonderfully modified, with the sexes borne 
on distinct plants, we may perhaps give the palm of 
victory to this genus. 

SECRETION OF NECTAR. 

Many Orchids, both our native species and the 
exotic kinds cultivated in our hothouses, secrete a 
copious supply of nectar. I have found the horn-like 
nectaries of Aerides filled with fluid ; and Mr. Kodgers, 
of Sevenoaks, informs me that he has taken crystals 
of sugar of considerable size from the nectary of A, 
cornutum. The nectar-secreting organs of the Orchideae 
present great diversities of structure and position in 
the various genera ; but are almost always situated 
towards the base of the labellum. In Disa, however, 
the posterior sepal alone, and in Disperis the two 
lateral sepals together with the labellum, secrete 
nectar. In Bendrobium chrysanthum the nectary 
consists of a shallow saucer ; in Evelyna, of two large 
united cellular balls ; and in Bolhophyllum cui^reum, of 
a medial furrow. In Cattleya the nectary penetrates 
the ovarium. In Angrsecum sesquipedale it attains the 
astonishing length of above eleven inches ; but I need 
not enter on further details. The fact, however, 
should be recalled, that in Coryanthes the nectar- 
secreting glands pour forth an abundance of almost 
pure water, which drips into a bucket formed by the 
distal part of the labellum ; and this secretion serves 
to prevent the bees which come to gnaw the surface of 
the labellum from flying away, and thus compels them 
to crawl out through the proper passage. 

Although the secretion of nectar is of the highest 



266 SECRETION OF NECTAE. Chap. IX. 

importance to Orcliids by attracting insects, which are 
indispensable for the fertilisation of most of the species, 
yet good reasons can be assigned for the belief* that 
nectar was aboriginally an excretion for the sake of 
getting rid of superfluous matter during the chemical 
changes which go on in the tissues of plants, especially 
W'hilst the sun shines. The bractese of some Orchids 
have been observed f to secrete nectar, and this cannot 
be of any use to them for their fertilisation. Fritz 
Muller informs me that he has seen such secretion 
from the bracteae of an Oncidium in its native Bra- 
zilian home, as well as from the bractese and from the 
outside of the upper sepal of a Notylia. Mr. Eodgers 
has observed a similar and copious secretion from the 
base of the flower-peduncles of Vanilla. The column 
of Acropera and Grongora likewise secretes nectar, as 
previously stated, but only after the flowers have been 
impregnated, and when such secretion could be of no 
use by attracting insects. It is in perfect accordance 
with the scheme of nature, as worked out by natural 
selection, that matter excreted to free the system from 
superfluous or injurious substances should be utilised 
for highly useful purposes. To give an example in 
strong contrast with our present subject, the larvae of 
certain beetles (Cassidae, &c.) use their own excrement 
to make an umbrella-like protection for their tender 
bodies. 

It may be remembered that evidence was given in 
the first chapter proving that nectar is never found 
within the spur-like nectaries of several species of 
Orchis, but that various kinds of insects penetrate 



* This subject has been fully 1876, p. 402. 

dispussed in my work 'On the t Kurr, 'Ueber die Bedeutung 

Effects of Cross and Silffertilisa- der Nektarien,' 18i?8, ]). 28. 
tion in the Vegetal ile K ugdom,' 



Chap. IX. SECKETION OF NECTAK, 267 

the tender inner coat with their proboscides, and suck 
the fluid contained in the inter-cellular spaces. This 
conclusion has been confirmed by Hermann Miiller, 
and I have further shown that even Lepidoptera are 
able to penetrate other and tougher tissues. It is an 
interesting case of co-adaptation that in all the British 
species, in which the nectary does not contain free 
nectar, the viscid matter of the disc of the poUinium 
requires a minute or two in order to set hard ; and 
it would be an advantage to the plant if insects were 
delayed thus long in obtaining the nectar by having 
to puncture the nectary at several points. On the 
other hand, in all the Ophreae which have nectar ready 
stored within the nectary, the discs are sufficiently 
viscid for the attachment of the pollinia to insects, 
without the matter quickly setting liard ; and there 
would therefore be no advantage to these plants in 
insects being delayed for a few minutes whilst sucking 
the flowers. 

In the case of cultivated exotic Orchids which have 
a nectary, without any free nectar, it is of course 
impossible to feel absolutely sure that it would not 
contain any under more natural conditions. Nor have 
I made many comparative observations on the rate of 
the setting hard of the viscid matter of the disc in 
exotic forms. Nevertheless it seems that some Yandeas 
are in the same predicament as our British species of 
Orchis ; thus Calanthe masuca has a very long nectary, 
which in all the specimens examined by me was quite 
dry internally, and was inhabited by powdery Cocci ; 
but in the intercellular spaces between the two coats 
there was much fluid ; and in this species the viscid 
matter of the disc, after its surface had been disturbed, 
entirely lost its adhesiveness in two minutes. In an 
Oncidium the disc, similarly disturbed, became dry in 



268 SECEETION OF NECTAR. Chap. IX. 

one minute and a half ; in an Odontoglossum in two 
minutes ; and in neither of these Orchids was there 
any free nectar. On the other hand, in Angrsecum 
sesquiijedale, which has free nectar stored within the 
lower end of the nectary, the disc of the pollinium, 
when removed from the plant and with its surface 
disturbed, was strongly adhesive after forty-eight 
hours. 

Sarcantlius teritifolius offers a more curious case. 
The disc quite lost its viscidity and set hard in less 
than three minutes. Hence it might have been ex- 
pected that no fluid would have been found in the 
nectary, but only in the intercellular spaces ; never- 
theless there was fluid in both places, so that here we 
have both conditions combined in the same flower. It 
is probable that insects would sometimes rapidly suck 
the free nectar and neglect that between the two 
coats; but even in this case I strongly suspect that 
they would be delayed by a totally different means 
in sucking the free nectar, so as to allow the viscid 
matter to set hard. In this plant, the labellum with 
its nectary is an extraordinary organ. I wished to 
have had a drawing made of its structure ; but found 
that it was as hopeless as to give a drawing of the 
wards of a complicated lock. Even the skilful Bauer, 
with numerous figures and sections on a large scale, 
hardly makes the structure intelligible. So com- 
plicated is the passage, that I failed in repeated 
attempts to pass a bristle from the outside of the 
flower into the nectary; or in a reversed direction 
from the cut-off end of the nectary to the outside. No 
doubt an insect with a voluntarily flexible proboscis 
could pass it through the passages, and thus reach 
the nectar ; but in effecting this, some delay would 
be caused ; and time would be thus allowed for the 



CuAP. IX. SECRETION OF NECTAE. 269 

curious square viscid disc to become securely cemented 
to an insect's head or body. 

As in Epipactis the cup at the base of the labellum 
serves as a nectar-receptacle, I expected to find that 
the analogous cups in Stanhopea, Acropera, &c., would 
serve for the same purpose ; but I could never find 
a drop of nectar in them. According, also, to M. 
Meniere and Mr. Scott * this is never the case in these 
genera, or in Gongora, Cirrhsea, and many others. In 
Catasetum tridentatum, and in the female form Mona- 
chanthus, we see that the upturned cup cannot 
possibly serve as a nectar-receptacle. What then 
attracts insects to these flowers ? That they must bo 
attracted is certain ; more especially in the case of Cata- 
setum, in which the sexes stand on separate plants. In 
many genera of Vandeee there is no trace of any nectar- 
secreting organ or receptacle ; but in all these cases 
(as far as I have seen), the labellum is either thick and 
fleshy, or is furnished with extraordinary excrescences, 
as in the genera Oncidium and Odontoglossum. In 
Phalasnopsis grayidiflora there is a curious anvil-shaped 
projection on the labellum, with two tendril-like pro- 
longations from its extremity which turn backwards 
and apparently serve to guard the sides of the anvil, so 
that insects would be forced to alight on its crown. 
Even in our British Cephalanthera grandiflora, the 
labellum of which never contains nectar, there are 
orange-coloured ribs and papillae on the inner surface 
which faces the column. In Calanthe (fig. 26) a cluster 
of odd little spherical warts projects from the labellum, 
and there is an extremely long nectary, which does 
not include nectar ; in Eidophia viridis the short nec- 
tary is equally destitute of nectar, and the labellum 



* 'Biillctin Bot. S.;c. de Franco,' toin. il. 1855, p 352. 



270 SECRETION OF NECTAR. Chap. IX, 

is covered with longitudinal, fimbriated ridges. In 
several species of Ophrys, there are two small shining 
protuberances, at the base of the labellum, beneath the 
two discs. Innumerable other cases could be added of 
the presence of singular and diversified excrescences 
on the labellum ; and Lindley remarks that their use 
is quite unknown. 

From the position, relatively to the viscid discs, 
which these excrescences occupy, and from the absence 
of any free nectar, it formerly seemed to me highly 
probable that they afi'orded food and thus attracted 
either Hymenoptera or flower-feeding Coleoptera. 
There is no more inherent improbability in a flower 
being habitually fertilised by an insect coming to 
feed on the labellum, than in seeds being habitually 
disseminated by birds attracted by the sweet pulp in 
which they are embedded. But I am bound to state 
that Dr. Percy, who had the thick and furrowed 
labellum of a Warrea analysed for me by fermentation 
over mercury, found that it gave no evidence of con- 
taining more saccharine matter than the other petals. 
On the other hand, the thick labellum of Catasetum 
and the bases of the upper petals of Mor modes ignea, 
have a slightly sweet, rather pleasant, and nutritious 
taste. Nevertheless, it was a bold speculation that 
insects were attracted to the flowers of various Orchids 
in order to gnaw the excrescences or other parts of 
their labella; and few things have given me more 
satisfaction than the full confirmation of this view by 
Dr. Criiger, who* has repeatedly witnessed in the AVest 
Indies humble-bees of the genus Euglossa gnawing the 
labellum of Catasetum, Coryanthes, Gongora, and 
Stanhopea. Fritz Miiller also has often found, in 



' Journ.- Linn. Soc. Bot.' 18G4, vol. viii. p. 129. 



CiiAi'. IX. MOVEMENTS OF THE POLLINIA. 271 

South Brazil, the prominences on the labellum of 
Oncidium gnawed. We are thus enabled to under- 
stand the meaning of the various extraordinary crests 
and projections on the labellum of many Orchids ; for 
they invariably stand in such a position that insects, 
whilst gnawing them, would be almost sure to touch 
the viscid discs of the pollinia and thus remove them, 
afterwards effecting the fertilisation of another flower. 



MOVEMENTS OF THE POLLINIA. 

The pollinia of many Orchids undergo a movement 
of depression, after they have been removed from their 
places of attachment and have been exposed for a few 
seconds to the air. This is due to the contraction of a 
portion, sometimes to an exceedingly minute portion, 
of the exterior surface of the rostellum, which retains 
a membranous condition. This membrane, as we have 
seen, is likewise sensitive to a touch, so as to rupture 
in certain definite lines. . In a Maxillaria the middle 
part of the pedicel, and in Habenaria the whole drum- 
like pedicel contracts. The point of contraction in all 
the other cases seen by me, is either close to the 
surface of attachment of the caudicle to the disc, or at 
the point where the pedicel is united to the disc ; but 
both the disc and pedicel are parts of the exterior 
surface of the rostellum. In these remarks I do not 
refer to the movements which are simply due to the 
elasticity of the pedicel, as in the Yandese. 

The long strap-formed disc of Gymnadenia conopsea 
is well adapted to show the mechanism of the move- 
ment of depression. The whole pollinium, both in its 
upright and depressed (but not closely depressed) 
position, has been shown (p. 6ij) in fig. 10. The disc, 
in its uncontracted condition with the caudicle removed, 




272 MOVEMENTS OF THE POLLINIA. Chap. IX. 

is seen from above highly magnified in the upper of 
the two adjoining figures ; and in the lower figure we 
have a longitudinal section of the uncontracted disc, 
together with the base of the attached and upright 
caudicle. At the broad end of the disc there is a deep 
crescent-shaped depression, bordered by a slight ridge 
formed of longitudinally elon- 
^'" * gated cells. The end of the 

caudicle is attached to the 
steep sides of this depression 
and ridge. When the disc is 
exposed to the air for about 
thirty seconds, the ridge con- 
tracts and sinks flat down ; in 

Disc o^Gyrr^nadeniaconopsea. ^^^-^^^^^ ^^ j.^gg ^i^h it the 

caudicle, which then lies parallel to the elongated 
tapering part of the disc. If placed in water the 
ridge rises, re-elevating the caudicle, and when re- 
exposed to the air it sinks again, but each time with 
somewhat enfeebled power. During each sinking and 
rising of the caudicle, the whole pollinium is of course 
depressed and elevated. 

That the power of movement lies exclusively in the 
surface of the disc is well shown in the case of the 
saddle-shaped disc of Orchis pyramidalis ; for whilst it 
was held under water I removed the attached caudicles 
and the layer of viscid matter from the inferior surface, 
and immediately that the disc was exposed to the air 
the proper contraction ensued. The disc is formed of 
several layers of minute cells, which are best seen in 
specimens that have been kept in spirits of wine, 
for their contents are thus rendered more opaque. The 
cells in the flaps of the saddle are a little elongated. 
As long as the saddle is kept damp, its upper surface 
is nearly flat, but when exposed to the air (see fig. 3, 



Chap. IX. MOVEMENTS OF THE POLLINIA. 273 

E, p. 18) the two flaps or sides contract and curl inwards ; 
and this causes the divergence of the poUinia. By a 
kind of contraction two valleys are likewise formed in 
front of the caudicles, so that the latter are thrown 
forwards and downwards, almost in the same way as if 
trenches were dug in front of two upright poles, and 
then carried on so as to undermine them. As far as I 
could perceive, an analogous contraction causes the 
depression of the pollinia in Orchis mascula. With 0. 
hircina both pollinia are attached to a single rather large 
square disc, the whole front of which, after exj)osure 
to the air, sinks down and is then separated from the 
hinder part by an abrupt step. By this contraction both 
pollinia are carried forwards and downwards. 

Some pollinia which had been gummed on card for 
several months, when placed in water, rose up and 
afterwards underwent the movement of depression. 
A fresh pollinium, on being alternately damped and 
exposed to the air, rises and sinks several times alter- 
nately. Before I had ascertained these facts, which 
show that the movement is simply hygrometric, I 
thought that it was a vital action, and tried vapour 
of chloroform and of prussic acid, and immersion in 
laudanum; but these reagents did not check the 
movement. Nevertheless, there are some difficulties 
in understanding how the movement can be simply 
hygrometric. The flaps of the saddle in Orchis pyra- 
midalis (see fig. 3, D, p. 18) curl completely inwards 
in nine seconds, which is a surprisingly short time 
for mere evaporation to produce an effect ;* and the 



* This fact does not now appear awn of Stipa twists and untwists 

to me so surprising as it feruieriy when exposed to dry and (iaijjp uLr. 

did, for niY son Francis has s^liowu Tliese movements being due, as 

( ' Transact. Linn. Soc' 2nd series, he has shown, to tlie twisting and 

But. vol. i. 1876, p. 14i») with untwisting of the separate cells, 
what extr .ordinary quickno.^s the 
13 



274 CONCLUDING REMARKS. Chap IX. 

movement is apparently due to the drying of the under 
surface, although this is covered with a thick layer 
of viscid matter. The edges, however, of the saddle 
might become slightly dry in the nine seconds. When 
the saddle-formed disc is placed in spirits of wine it 
contracts energetically ; and this is probably due to 
the attraction of alcohol for water. When replaced in 
water it opens again. Whether or not the contraction 
is wholly hygrometric, the movements are admirably 
regulated in each species, so that the pollen-masses, 
when transported by insects from flower to flower, 
assume a proper position for striking the stigmatic 
surface. 

These various movements would be quite useless, 
unless the pollinia were attached in a uniform position 
to the insects which visit the flowers so as to be always 
directed in the same manner after the movement of 
depression ; and this necessitates that the insects should 
be forced to visit the flowers of the same species in 
a uniform manner. Hence I must say a few words 
on the sepals and petals. Their primary function, no 
doubt, is to protect the organs of fructification in the 
bud. After the flower is fully expanded, the upper 
sepal and two upper petals often continue the same 
office. We cannot doubt that this protection is of 
service, when we see in Stelis the sepals so neatly re- 
closing and reprotecting the flower some time after its 
expansion ; in Masdevallia the sepals are permanently 
soldered together, with two little windows alone left 
open ; and in the open and exposed flowers of Bol- 
bophyllum, the mouth of the stigmatic chamber 
after a time closes. Analogous facts with respect to 
Malaxis, Cephalanthera, &c., could be given. But the 
hood formed by the upper sepal and two upper petals, 
besides affording protection, evidentlv forms a guide, 



Chaf IX. CONCLUDING REMAKKS. 275 

compelling insects to visit the flowers in front. Few 
persons now doubt the correctness of C. K. Sprengel's 
view, * that the bright and conspicuous colours of 
flowers serve to attract insects from a distance. Never- 
theless some Orchids have singularly inconspicuous 
and greenish flowers, perhaps in order to escape some 
danger ; but many of these are strongly scented, which 
would equally well serve to attract insects. 

The labellum is by far the most important of the 
external envelopes of the flower. It not only secretes 
nectar, but is often modelled into variously shaped 
receptacles for holding this fluid, or is itself rendered 
attractive so as to be gnawed by insects. Unless the 
flowers were by some means rendered attractive, most 
of the species would be cursed with perpetual sterility. 
The labellum always stands in front of the rostelium, 
and its outer portion often serves as a landing-place 
for the necessary visitors. In Epipactis j^ct^f^stris this 
part is flexible and elastic, and apparently compels 
insects in retreating to brush against the rostelium. 
In Cypripedium the distal portion is folded over like 
the end of a slipper, and compels insects to crawl out 
of the flower by one of two special passages. In Ptero- 
stylis and a few other Orchids the labellum is irritable, 
so that when touched it shuts the flower, leaving only 
a single passage by which an insect can escape. In 
Spiranthes, when the flower is fully mature, the column 
moves from the labellum, space being thus left for 



* This author's curious work, own observations, tliat his work 
with its quaint title of ' Das Ent- contains an immense bo'iy of 
ieckte Geheiraniss der Natur,' truth. Many years ago Robert 
until lately was often spoken Brown, to whot^e judprment all 
lightly of. No doubt he whs an botanists defer, spoke hipilily of it 
enthusiast, and perliaps carried to me, and remarked that only 
some of his ideas to an extreme those who knew little of tlie nub- 
length. But I feel sure, from my j<ct would laugh at him. 



276 CONCLUDING REMARKS. Chap. IX. 

the introduction of tlie pollen-masses attached to the 
proboscis of a humble-bee. In Mormodes ignea the 
labellum is perched on the summit of the column, 
and here insects alight and touch a sensitive point, 
causing the ejection of the pollen-masses. The la- 
bellum is often deeply channelled, or has guiding 
ridges, or is pressed closely against the column ; and 
in a multitude of cases it approaches closely enough 
to render the flower tubular. By these several means 
insects are forced to brush against the rostellum. We 
must not, however, suppose that every detail of struc- 
ture in the labellum is of use : in some instances, as 
with Sarcanthus, its extraordinary shape seems to be 
partly due to its development in close apposition to 
the curiously shaped rostellum. 

In Listera ovata the labellum stands far from the 
column, but its base is narrow, so that insects are led 
to stand exactly beneath the middle of the rostellum. 
In other cases, as in Stanhopea, Phalaenopsis, Gongora, 
&c., the labellum is furnished with upturned basal 
lobes, which manifestly act as lateral guides. In some 
cases, as in Malaxis, the two upper petals are curled 
backwards so as to be out of the way ; in other cases 
as in Acropera, Masdevallia, and some Bolbophyllums, 
these upper petals plainly serve as lateral guides, com- 
pelling insects to visit the flowers directly in front of 
the rostellum. In other cases, wings formed by the 
margins of the clinandrum or of the column, serve as 
lateral guides, both in the withdrawal of the pollinia 
and in their subsequent insertion into the stigmatic 
cavity. So that there can be no doubt that the petals, 
sepals and rudimentary anthers do good service in 
several ways, besides affording protection to the bud. 

The final end of the whole flower, with all its parts, 
is the production of seed ; and these are produced by 



Chap. IX CONCLUDING REMARKS. 277 

Orchids in vast profusion. Not that such profusion 
is anything to boast of; for the production of an ahnost 
infinite number of seeds or eggs, is undoubtedly a sign 
of lowness of organisation. That a plant, not being 
an annual, should escape extinction, chiefly by the 
production of a vast number of seeds or seedlings, 
shows a poverty of contrivance, or a want of some 
fitting protection against other dangers. I was curious 
to estimate the number of seeds produced by some 
few Orchids ; so I took a ripe capsule of Cephalanthera 
grandijlora, and arranged the seeds on a long ruled 
line as equably as I could in a narrow hillock ; and 
then counted the seeds in an accurately measured 
length of one-tenth of an inch. In this way the con- 
tents of the capsule were estimated at 6020 seeds, and 
very few of these were bad; the four capsules borne 
by the same plant would have therefore contained 
24,080 seeds. Estimating in the same manner the 
smaller seeds of Orchis maculata, I found the number 
nearly the same, viz., 6200 ; and, as I have often seen 
above thirty capsules on the same plant, the total 
amount would be 186,300. As this Orchid is perennial, 
and cannot in most places be increasing in number, 
one seed alone of this large number yields a mature 
plant once in every few years. 

To give an idea what the above figures really mean, 
I will briefly show the possible rate of increase of 0. 
maculata: an acre of land would hold 174,240 plants, 
each having a space of six inches square, and this 
would be just sufficient for their growth ; so that, 
making the fair allowance of 400 bad seeds in eacli 
capsule, an acre would be thickly clothed by the pro- 
geny of a single plant. At the same rate of increase, 
the grandchildren would cover a space slightly exceed- 
ing the island of Anglesea ; and the great grand- 



278 CONCLUDING REMARKS. Chap. IX. 

children of a single plant would nearly (in the ratio of 
47 to 50) clothe with one uniform green carpet the 
entire surface of the land throughout the globe. But 
the number of seeds produced by one of our common 
British orchids is as nothing compared to that of some 
of the exotic kinds. Mr. Scott found that the capsule 
of an Acropera contained 371,250 seeds ; and judging 
from the number of flowers, a single plant would some- 
times yield about seyenty-four millions of seeds. 
Fritz Miiller found 1,756,440 seeds in a single capsule 
of a Maxillaria ; and the same plant sometimes bore 
half-a-dozen such capsules. I may add that by 
counting the packets of pollen (one of which was broken 
up under the microscope) I estimated that the number 
of pollen-grains, each of which emits its tube, in a 
single anther of Orchis mascula was 122,400. Amici* 
estimated the number in 0. morio at 120,300. As 
these two species apparently do not produce more 
seed than the allied 0. maculata, a capsule of which 
contained 6200 seeds, we see that there are about 
twenty pollen-grains for each ovule. According to 
this standard, the number of pollen-grains in the 
anther of a single flower of the Maxillaria which 
yielded 1,756,440 seeds must be prodigious. 

What checks the unlimited multiplication of the 
Orchidese throughout the world is not known. The 
minute seeds within their lio-ht coats are well fitted 
for wide dissemination ; and I have several times 
obseiTcd seedlings springing up in my orchard and in 
a newly-planted wood, which must have come from a 
considerable distance. This was especially the case 
with EiniKictis latifolia ; and an instance has been ro 
corded by a good observer f ot seedlings of this plant 

* Mohl. 'The VeiTfta])!.' Coll,' f Mr. Broe, in 'T.ouHon*8 Ma^'. 

translated by Heiilrcy, i). 1^6. ot Nut. Hist,' vol. ii. 1829, p. 70. 



Chap. IX. CONCLUDING REMAKES. 279 

appearing at the distance of between eight and ten 
miles from any phice where it grew. Notwithstanding 
the astonishing number of seeds produced by Orchids, 
it is notorious that they are sparingly distributed ; for 
instance, Kent appears to be the most favourable county 
in England for the order, and within a mile of my 
house nine genera, including thirteen species, grow ; 
but of these one alone. Orchis morio, is sufficiently 
abundant to make a conspicuous feature in the vege- 
tation ; as is 0. maculata in a lesser degree in open 
woodlands. Most of the other species, though not 
deserving to be called rare, are sparingly distributed ; 
yet, if their seeds or seedlings were not largely de- 
stroyed, any one of them would immediately cover the 
whole land. In the tropics the species are very much 
more numerous; thus Fritz Muller found in South 
Brazil more than thirteen kinds belonging to several 
genera growing on a single Cedrela tree. Mr. Fitz- 
gerald has collected within the radius of one mile of 
Sydney in Australia no less than sixty-two species, of 
which fifty-seven were terrestrial. Nevertheless the 
number of individuals of the same species is, I believe, 
in no country nearly so great as that of very many 
other plants. Lindley formerly estimated that there 
were in the world about 6000 sjjecies of Orchideas, 
included in 433 genera.* 

The number of the individuals which come to 
maturity does not seem to be at all closely determined 
by the number of seeds which each species produces ; 
and this holds good when closely related forms are 
compared. Thus Ophrys apifera fertilises itself and 
every flower produces a capsule ; but the individuals 
of this species are not so numerous in some parts of 



» • Gardener's Cliron.' 1862, p. 192. 



280 CONCLUDING REMARKS. Chap. IX. 

England as those of 0. muscifera, which cannot fer- 
tilise itself and is imperfectly fertilised by insects, so 
that a large proportion of the flowers drop off unim- 
pregnated. Ophrys aranifera is found in large numbers 
in Liguria, yet Delpino estimates that not more than 
one out of 3000 flowers produces a capsule.* Mr. 
Cheeseman saysf that with the New Zealand Ptero- 
stylis truUifolia much less than a quarter of the flowers, 
which are beautifully adapted for cross-fertilisation, 
yield capsules ; whereas with the allied Aeianthus 
sinclairii, the flowers of which equally require insect- 
aid for their fertilisation, seventy-one capsules were 
produced by eighty-seven flowers ; so that this plant 
must produce an extraordinary number of seeds ; never- 
theless in many districts it is not at all more abundant 
than the Pterostylis. Mr. Fitzgerald, who in Aus- 
tralia has particularly attended to this subject, remarks 
that every flower of Thehjmitra carnea fertilises itself 
and produces a capsule ; yet it is not nearly so common 
as Aeianthus fornicatus, " the majority of the flowers 
of which are unproductive. Phajus grandifolius and 
CalantJie veratrifolia grow in similar situations. Every 
flower of the Phajus produces seeds, only occasionally 
one of the Calanthe, yet Phajus is rare and Calanthe 
common." 

The frequency with which throughout the world 
members of various Orchideous tribes fail to have their 
flowers fertilised, though these are excellently con- 
structed for cross-fertilisation, is a remarkable fact. 
Fritz Muller informs me that this holds good in the 
luxuriant forests of South Brazil with most of the 
Epidendrete, and with the genus Vanilla. For instance, 



* 'Ult. Osservaz. siiUa Dico- f Transact. New Zealand Inst, 

gamia,' part i. p. 177. vol. vii. 1875, p. 351. 



Chap. IX. CONCLUDING REMARKS. 281 

he visited a site where Vanilla creeps over almost every 
tree, and although the plants had been covered with 
flowers, yet only two seed-capsules were produced. So 
again with an Epidendrum, 233 flowers had fallen off 
unimpregnated and only one capsule had been formed ; 
of the still remaining 136 flowers, only four had their 
pollinia removed. In New South Wales Mr. Fitzgerald 
does not believe that more than one flower out of a 
thousand of Dendrdbium si:>eciosum sets a capsule ; and 
some other species there are very sterile. In New 
Zealand over 200 flowers of Coryanthes triloba yielded 
only five capsules ; and at the Cape of Good Hope only 
the same number were produced by 78 flowers of Disa 
grancliflora. Nearly the same result has been observed 
with some of the species of Ophrys in Europe. The 
sterility in these cases is very difiicult to explain. It 
manifestly depends on the flowers being constructed 
with such elaborate care for cross-fertilisation, that they 
cannot yield seeds without the aid of insects. From 
the evidence which I have given elsewhere * we may 
conclude that it would be far more profitable to most 
plants to yield a few cross -fertilised seeds, at the 
expense of many flowei-s dropping off unimpregnated, 
rather than produce many self-fertilised seeds. Profuse 
expenditure is nothing unusual under nature, as we see 
with the pollen of wind-fertilised plants, and in the 
multitude of seeds and seedlings produced by most 
plants in comparison with the few that reach maturity. 
In other cases the paucity of the flowers that are im- 
pregnated may be due to the proper insects having 
become rare under the incessant changes to which the 
world is subject ; or to other plants which are more 



♦ ♦ Tho Effects of Cioss and Self-fertilisation in the Vegetable 
Kingdom,' 1876. 



282 CONCLUDING REMARKS. Chap. IX. 

highly attractive to the proper insects having increased 
in number. We know that certain Orchids require 
certain insects for their fertilisation, as in the cases be- 
fore given of Vanilla and Sarcochilus. In Madagascar 
Angrdecum sesqui2)edale must depend on some gigantic 
moth. In Europe Gypripedium calceolus appears to be 
fertilised only by small bees of the genus Andrena, 
and Epipactis latifolia only by wasps. In those cases 
in which only a few flow^ers are impregnated owing to 
the proper insects visiting only a few, this may be a 
great injury to the plant ; and many hundred species 
throughout the world have been thus exterminated ; 
those which survive having been favoured in some 
other way. On the other hand, the few seeds which 
are produced in these cases will be the product of 
cross-fertilisation, and this as we now positively know 
is an immense advantage to most plants. 

I have now nearly finished this volume, which is 
perhaps too lengthy. It has, I think, been shown that 
the Orchideae exhibit an almost endless diversity of 
beautiful adaptations. When this or that part has been 
spoken of as adapted for some special purpose, it must 
not be supposed that it was originally always formed 
for this sole purpose. The regular course of events 
seems to be, that a part which originally served for one 
purpose, becomes adapted by slow changes for widely 
different purposes. To give an instance : in all the 
Ophrese, the long and nearly rigid caudicle manifestly 
serves for the application of the pollen-grains to the 
stigma, when the pollinia are transported by insects 
to another flower ; and the anther opens widely in 
order that the pollinium should be easily withdrawn ; 
but in the Bee Ophrys, the caudicle, by a slight in- 
crease in length and decrease in its thickness, and by 



Chap. IX. CONCLUDING REM AKKS. 283 

the anther opening a little more widely, becomes 
specially adapted for the very ditferent purpose of 
self-fertilisation, through the combined aid of the 
weight of the pollen-mass and the vibration of the 
flower when moved by the wind. Every gradation 
between these two states is possible, — of which we have 
a partial instance in aranifera. 

Again, the elasticity of the pedicel of the poUinium 
in some Yandese is adapted to free the pollen-masses 
from their anther-cases ; but by a further slight modi- 
fication, the elasticity of the pedicel becomes specially 
adapted to shoot out the pollinium with considerable 
force so as to strike the body of the visiting insect. 
The great cavity in the labellum of many Yandeee 
is gnawed by insects and thus attracts them; but 
in Mor modes ignea it is greatly reduced in size, and 
serves in chief part to keep the labellum in its new 
position on the summit of the column. From the 
analogy of many plants we may infer that a long 
spur-like nectary is primarily adapted to secrete and 
hold a store of nectar ; but in many Orchids it has so 
far lost this function, that it contains fluid only in the 
intercellular spaces. In those Orchids in which the 
nectary contains both free nectar and fluid in the inter- 
cellular spaces, we can see how a transition from the 
one state to the other could be effected, namely, by 
less and less nectar being secreted from the inner 
membrane, with more and more retained within the 
intercellular spaces. Other analogous cases could be 
given. 

Although an organ may not have been originally 
formed for some special purpose, if it now serves for 
this end, we are justified in saying that it is specially 
adapted for it. On the same principle, if a man were 
to make a machine for some special purpose, but were 



284 CONCLUDING REMARKS. Chap. IX 

to use eld wheels, springs, and pulleys, only slightly 
altered, the whole machine, with all its parts, might be 
said to be specially contrived for its present purpose. 
Thus throughout nature almost every part of each living 
being has probably served, in a slightly modified con- 
dition, for diverse purposes, and has acted in the living 
machinery of many ancient and distinct specific forms. 

In my examination of Orchids, hardly any fact has 
struck me so much as the endless diversities of structure, 
— the prodigality of resources, — ^for gaining the very 
same end, namely, the fertilisation of one flower by 
pollen from another plant. This fact is to a large ex- 
tent intelligible on the principle of natural selection. 
As all the parts of a flower are co-ordinated, if slight 
variations in any one part were preserved from being 
beneficial to the plant, then the other parts would 
generally have to be modified in some corresponding 
manner. But these latter parts might not vary at all, 
or they might not vary in a fitting manner, and these 
other variations, whatever their nature might be, which 
tended to bring all the parts into more harmonious 
action with one another, would be preserved by natural 
selection. 

To give a simple illustration : in many Orchids the 
ovarium (but sometimes the foot-stalk) becomes for a 
period twisted, causing the labellum to assume the 
position of a lower petal, so that insects can easily 
visit the flower; but from slow changes in the form 
or position of the petals, or from new sorts of insects 
visiting the flowers, it might be advantageous to the 
plant that the labellum should resume its normal 
position on the upper side of the flower, as is actually 
the case with Malaxis 2?aludosa, and some species of 
Catasetum, &c. This change, it is obvious, might be 
simply effected by the continued selection of varieties 



Chap. IX CONCLUDING KEMAKKS. 285 

which had their ovaria less and less twisted, but if 
the plant only afforded varieties with the ovarium 
more twisted, the same end could be attained by the 
selection of such variations, until the flower w^as 
turned completely round on its axis. This seems to 
have actually occurred with Malaxis paludosa, for 
the labellum has acquired its present upward posi- 
tion by the ovarium being twisted twice as much as 
is usual. 

Again, we have seen that in most Vandese there is 
a plain relation between the depth of the stigmatic 
chamber and the length of the pedicel, by which the 
pollen-masses are inserted ; now if the chamber became 
slightly less deep from any change in the form of the 
column or other unknown cause, the mere shortening 
of the pedicel would be the simplest corresponding 
change ; but if the pedicel did not happen to vary in 
shortness, the slightest tendency to its becoming bowed 
from elasticity as in Phalaenopsis, or to a backward 
hygrometric movement as in one of the Maxillarias, 
would be preserved, and the tendency would be con- 
tinually augmented by selection ; thus the pedicel, as 
far as its action is concerned, would be modified in 
the same manner as if thad been shortened. Such 
processes carried on during many thousand generations 
in various ways, w^ould create an endless diversity of 
co-adapted structures in the several parts of the flower 
for the same general purpose. This view affords, I 
believe, the key which partly solves the problem of the 
vast diversity of structure adapted for closely analogous 
ends in many large groups of organic beings. 

The more I study nature, the more I become 
impressed with ever-increasing force, that the con- 
trivances and beautiful adaptations slowly acquired 
through each part occasionally varying in a slight 



286 CONCLUDING REMARKS. Chap. IX 

degree but in many ways, with the preservation of those 
variations which were beneficial to the organism under 
comjDlex and ever- varying conditions of life, transcend 
in an incomparable manner the contrivances and 
adaptations which the most fertile imagination of man 
could invent. 

The use of each trifling detail of structure is far 
from a barren search to those who believe in natural 
selection. When a naturalist casually takes up the 
study of an organic being, and does not investigate 
its whole life (imperfect though that study will ever 
be), he naturally doubts whether each trifling point 
can be of any use, or indeed whether it be due to any 
general law. Some naturalists believe that number- 
less structures have been created for the sake of mere 
variety and beauty, — much as a workman would make 
different patterns. I, for one, have often and often 
doubted whether this or that detail of structure in 
many of the Orchidese and other plants could be of 
any service ; yet, if of no good, these structures could 
not have been modelled by the natural preservation of 
useful variations; such details can only be vaguely 
accounted for by the direct action of the conditions of 
life, or the mysterious laws of correlated growth. 

To give nearly all the instances of trifling details 
of structure in the flowers of Orchids, which are cer- 
tainly of high importance, would be to recapitulate 
almost the whole of this volume. But I will recall 
to the reader's memory a few cases. I do not here refer 
to the fundamental framework of the plant, such as 
the remnants of the fifteen primary organs arranged 
alternately in the five whorls ; for almost everyone who 
believes in the gradual evolution of species will admit 
that their presence is due to inheritance from a remote 
parent-form. Innumerable facts with respect to the 



Chap. IX. CONCLUDING REMAKKS. 287 

uses of the variously shaped and placed petals and 
sepals have been given. So again, the importance of 
as light difference in the shape of the caudicle of the 
pollinium of the Bee Ophrys, compared with that of 
the other species of the same genus, has likewise been 
referred to ; to this might be added the doubly-bent 
caudicle of the Fly Ophrys. Indeed, the important 
relation of the length and shape of the caudicle, with 
reference to the position of the stigma, might be cited 
throughout many whole tribes. The solid projecting 
knob of the anther in Epipactis palustris, which does 
not include pollen, liberates the pollen-masses when it 
is moved by insects. In CephalaniJiera grandiflora, the 
upright position of the almost closed flower protects 
the slightly coherent pillars of pollen from disturb- 
ance. The length and elasticity of the filament of the 
anther in certain species of Dendrobium apparently 
serves for self-fertilisation, if insects fail to transport 
the pollen-masses. The slight forward inclination of 
the crest of the rostellum in Listera prevents the 
anther-case boing caught as soon as the viscid matter 
is ejected. The elasticity of the lip of the rostellum 
in Orchis causes it to spring up again when only one 
of the pollen-masses has been removed, thus keeping 
the second viscid disc ready for action, which otherwise 
would be wasted. No one who had not studied Orchids 
would have suspected that these and very many other 
small details of structure were of the highest importance 
to each species ; and that consequently, if the species 
were exposed to new conditions of life, and the structure 
of the several parts varied ever so little, the smallest 
details of structure might readily be acquired through 
natural selection. These cases afford a good lesson of 
caution with respect to the importance of apparently 
trifling particulars of structure in other organic beings. 



288 CONCLmTiNG remarks. Chap. IX. 

It may naturally be inquired, Why do the Orchideae 
exhibit so many perfect contrivances for their fertili- 
sation? From the observations of various botanists 
and my own, I am sure that many other plants offer 
analogous adaptations of high perfection ; but it seems 
that they are really more numerous and perfect with 
the Orchidea3 than with most other plants. To a 
certain extent this inquiry can be answered. As each 
ovule requires at least one, probably several, pollen- 
grains,* and as the seeds produced by Orchids are so 
inordinately numerous, we can see that it is necessary 
that large masses of pollen should be left on the stigma 
of each flower. Even in the Neottese, which have 
granular pollen, with the grains tied together by weak 
threads, I have observed that considerable masses of 
pollen are generally left on the stigmas. This cir- 
cumstance apparently explains why the grains cohere 
in packets or large waxy masses, as they do in so 
many tribes, namely, to prevent waste in the act of 
transportal. The flowers of most plants produce pollen 
enouo^h to fertilise several flowers, so as to allow of or to 
favour cross-fertilisation. But with the many Orchids 
which produce only two pollen-masses, and with some of 
the Malaxese which produce only one, the pollen from 
a single flower cannot possibly fertilise more than two 
flowers or only a single one ; and cases of this kind 
do not occur, as I believe, in any other group of 
plants. If the Orchidese had elaborated as much 
pollen as is produced by other plants, relatively to the 
number of seeds which they yield, they would have 
had to produce a most extravagant amount, and this 
would have caused exhaustion. Such exhaustion is 
avoided by pollen not being produced in any great 

♦ Gartner, ' Beitr'age zur KenntIli.'^s der BcfrucbtiiDg,' 1844, p. 135. 



Chap. IX. CONCLUDING KEMAKKS. 289 

superfluity owing to the many special contrivances for 
its safe transportal from plant to plant, and for placing 
it securely on the stigma. Thus we can understand 
why the Orchidese are more highly endowed in their 
mechanism for cross-fertilisation, than are most other 
plants. 

In my work on the "Effects of Cross and Self 
Fertilisation in the Vegetable Kingdom," I have shown 
that when flowers are cross-fertilised they generally 
receive pollen from a distinct plant and not that from 
another flower on the same plant ; a cross of this latter 
kind doing little or no good. I have further shown 
that the benefits derived from a cross between two 
plants depends altogether on their differing some- 
what in constitution ; and there is much evidence that 
each individual seedling possesses its own peculiar 
constitution. The crossing of distinct plants of the 
same species is favoured or determined in various 
ways, as described in the above work,- but chiefly 
by the prepotent action of pollen from another 
plant over that from the same flower. Now with the 
Orchideae it is highly probable that such prepotency 
prevails, for we know from the valuable observa- 
tions of Mr. Scott and Fritz Mliller,* that with several 
Orchids pollen from their own flower is quite im- 
potent, and is even in some cases poisonous to the 
stigma. Besides this prepotency, the Orchideae pre- 
sent various special contrivances — such as the pollinia 
not assuming a proper position for striking the stigma 
until some time has elapsed after their removal from 
the anthers — the slow curving forwards and then back- 
wards of the rostellum in Listera and Neottia — the 



* A full abe tract of these ob- Domestication,' cli. xvii. 2ud edit. 
servatioMs is given in my ^V;iria- vol. ii. p. 114. 
tion of Auimald and Plants under 



290 CONCLUDING REMARKS. Ohap. IX. 

slow movement of the column from the labellum in 
Spiranthes — the dioecious condition of Catasetum — 
the fact of some species producing only a single 
flower, &c. — all render it certain or highly probable 
that the flowers are habitually fertilised with pollen 
from a distinct plant. 

That cross-fertilisation, to the complete exclusion of 
self-fertilisation, is the rule with the Orchidese, cannot 
be doubted from the facts already given in relation to 
many species in all the tribes throughout the world. 
I could almost as soon believe that flowers in general 
were not adapted for the production of seeds, because 
there are a few plants which have never been known to 
yield seed, as that the flowers of the Orchidese are not 
as a general rule adapted so as to ensure cross-fertilisa- 
tion. Nevertheless, some species are regularly or often 
self-fertilised; and I will now give a list of all the 
cases hitherto observed by myself and others. In some 
of these the flowers appear often to be fertilised by 
insects, but they are capable of fertilising themselves 
without aid, though in a more or less incomplete 
manner ; so that they do not remain utterly barren if 
insects fail to visit them. Under this head may be 
included three British species, namely, CepJialanthera 
graiidiflora, Neottia nidus-avis, and perhaps List era 
ovata. In South Africa Bisa macrantha often fertilises 
itself ; but Mr. Weale believes that it is likewise cross- 
fertilised by moths. Three species belonging to the 
Epidendrese rarely open their flowers in the West 
Indies ; nevertheless these flowers fertilise themselves, 
but it is doubtful whether they are fully fertilised, 
for a large proportion of the seeds spontaneously pro- 
duced by some members of this tribe in a hothouse 
were destitute of an embryo. Some species of Dendro- 
bium, judging from their structure and from their 



Chap. IX. CONCLUDING EEMAEKS. 291 

occasionally producing capsules under cultiyation, 
likewise come under this head. 

Of species which regularly fertilise themselves with- 
out any aid and yield full-sized capsules, hardly any 
case is more striking than that of Oplirys apifera, which 
was advanced by me in the first edition of this work. 
To this case may now be added two other European 
plants, Orcliis or Neotinea intada and Upipactis viricli- 
tlora. Two North American species, Gymnadenia 
tridentata and Platanthera hyperhorea appear to be in 
the same predicament, but whether when self-fertilised 
they yield a full complement of capsules containing 
good seeds has not been ascertained. A curious 
Epidendrum in South Brazil which bears two additional 
anthers fertilises itself freely by their a id ; and Dendro- 
hium cretaceum has been known to produce perfect self- 
fertilised seeds in a hothouse in England. Lastly, 
Spiranthes australis and two species of Thelymitra, 
inhabitants of Australia, come under this same head. 
No doubt other cases will hereafter be added to this 
short list of about ten species which it appears can 
fertilise themselves fully, and of about the same 
number of species which fertilise themselves imper- 
fectly when insects are excluded. 

It deserves especial attention that the flowers of all 
the above-named self-fertile species still retain various 
structures which it is impossible to doubt are adapted 
for insuring cross-fertilisation, though they are now 
rarely or never brought into play. We may therefore 
conclude that all these plants are descended from 
species or varieties which were formerly fertilised by 
insect-aid. Moreover, several of the genera to which 
these self-fertile species belong, include other species, 
which are incapable of self-fertilisation. Thelymitra 
offers indeed the oulv instance known to me of two 



2-92 CONCLUDING REMARKS. Chap. IX. 

species within the same genus which regularly ferti- 
lise themselves. Considering such cases as those of 
Ophrys, Disa, and Epidendrum, in which one species 
alone in the genus is capable of complete self-ferti- 
lisation, whilst the other species are rarely fertilised 
in any manner owing to the rarity of the visits of 
the proper insects; — bearing also in mind the large 
number of species in many parts of the world which 
from this same cause are seldom impregnated, we are 
led to believe that the above-named self-fertile plants 
formerly depended on the visits of insects for their 
fertilisation, and that from such visits failing they did 
not yield a sufficiency of seed and were verging towards 
extinction. Under these circumstances it is probable 
that they were gradually modified, so as to become 
more or less completely self-fertile; for it would 
manifestly be more advantageous to a plant to pro- 
duce self-fertilised seeds rather than none at all or 
extremely few seeds. Whether any species which is 
now never cross-fertilised will be able to resist the 
evil effects of long-continued self-fertilisation, so as to 
survive for as long an average period as the other 
species of the same genera which are habitually cross- 
fertilised, cannot of course be told. But 0])lirys a^ifera 
is still a highly vigorous plant, and Gyninadenia triden- 
tata and Platanthera hyperhorea are said by Asa Gray 
to be common plants in North America. It is indeed 
possible that these self-fertile species may revert in 
the course of time to what was undoubtedly their 
pristine condition, and in this case their various adap- 
tations for cross-fertilisation would be again brought 
into action. We may believe that such reversion is 
possible, when we hear from Mr. Moggridge that 
Ophrys scolopax fertilises itself freely in one district 
of Southern France without the aid of insects, and 



CiiAP. IX. CONCLUDING BEMARKS. 293 

is completely sterile without such aid in another 
district. 

Finally, if we consider how precious a substance 
pollen is, and what care has been bestowed on 
its elaboration and on the accessory parts in the 
Orchideae, — considering how large an amount is 
necessary for the impregnation of the almost innumer- 
able seeds produced by these plants, — considering that 
the anther stands close behind or above the stigma, 
self-fertilisation would have been an incomparably 
safer and easier process than the transportal of pollen 
from flower to flower. Unless we bear in mind the 
good effects which have been proved to follow in most 
cases from cross-fertilisation, it is an astonishing fact 
that the flowers of the Orchidese should not have been 
regularly self-fertilised. It apparently demonstrates 
that there must be something injurious in this latter 
process, of which fact I have elsewhere given direct 
proof. It is hardly an exaggeration to say that Nature 
tells us, in the most emphatic manner, that she abhors 
perpetual self-fertilisation. 



INDEX 



BRO"WN. 



At'tsras anthropophora, 26; pollen- 


Battersby, Dr., obh'gations to, 106 


tubes, 258 


Buuer, Mr., on pollen-grains in 


longibracteafa, 2G 


Cephalanthera, 80, 82 ; on pollen- 


, monstrous flowers, 255 


masses of Bletia, 148 


Acianthus exsertus. 90 


B:e Ophrvs, 52 


fornicatus, 90, 280 


Beer, J. G., on Catasetum, 197 ; on 


Sinclair a, 90; fertil-sed by 


Cycnoclies, 224 


insects, 280 


Bees wifcii attached pollinia, 80 


Acontia luduosa with polleii-iuassir s. 


Belt, Mr., on Aiigrxcxiia sesquipe- 


31 


dale, 165 


Aa-opera, pnllinia of, 154, 156; 


Benthaiu on monstrous flowers of 


upper petals, 276 


( hchis pyramidalis, 88 


loddiqes/i, IGG 


Inid's-ueot Orchis, 125 


lufeola, 16G; vessels of, 289 


Bolbophyllicm, 274 ; upper petals, 


Adaptations, how far special, 2G7; 


276 


diversity (^f, 282 


barbigerttm, 138 


Aerides, movement of pollinia, l^Q; 




secretion of nectar, 2G5 


cupreum, 137 ; nectary of, 


cornutum, 2 Go 


2G5 




rhizoplwrx, 137 




Bonatea speciosa, 71, 76 ; vessels of. 


Amici, on number of poUen-giains 


244 ; modified structure, 264 ; 


in Orchis morio, 278 


candicln, 361 


Anderson, Mr., on Dendrobium,H2 ; 


Bond, Mr. F., on moths with at- 


on the Epidendrea, 147 


tached pollinia, 30; obligations 


AngriBcum, viscid matter in, 251 


to, 72, 75 


distichum, 154 


Eractese, secreting nectar, 266 




Brasaia, movement of pollinia, 156 


sesquipedale, 154, 162, 282; 


Bree, Mr., on seed of Euipactu 


nectary of, 265 


latif alia, 278 


Antennae of the rostellura of Cala- 


Brongiiiart, M., on secretion of 


setum, 184, 187 


nectar, 41; on Catasetum, 196; 


Anthers, rudimentary, 240 


spiral vessels in Orchids, 285; on 


Apostasia, 248 


Uropedium, 240 


Arethusex, 80 


Broun, Prof., on Stanhnpea devo- 


Auricles, or papillaj, rudimentary, 


niensis, 171 ; classification of or- 


241, 242 


ganic beings, 264 




Brown, C, on Sobral a macranfha,9l 


Babington, Prof., on the rostclluni, 


, Piobeit, on the fertilisation of 


255 


Orchids, 3 ; viscidity of stigma^ 


Baillon, M., on Cataseium, 191 


13; Ophrys ap/fera, 54; utriculi 


Barkeria, 146. 


of the stigma, 202 ; homologies of 


Bateman, Mr., obligations to, 105, 


Orchids, 234, 235, 237 ; rostellum 


162; on Ci/cnoches, 224. 


of Orchids, 247 ; Apostasia, 248 ; 



BUTTEKFLIES. 



INDEX. 



DEXDKOBIUM. 



295 



polL-n-tubes, 258 ; Sprengel's 

work, 275 
Biitteifiies with attached polliuia, 

31 
Butterfly orchis, 69 
, Itsser, 73 

Caladenia dimorpha, 89 

Cahkna. 89 

Calanthe dominii, 161 

vtasuca, structure of flower, 

161 ; long nectary, 267, 269 

veratrifolia, 280 

vest it a, 162 

Carpi nter, Dr., on Myantlms and 
Caiasetum, 196 

Catasetidx, 178 

Catasetum, peculiar rostellum, 256 ; 
labellum, 270 

callosum, 192, 195 

luridum, 191 

mentosmn, 206 

planieeps, 193 

saccatum, structure of flower, 

180-185; vessels of, 239 

tabulare, 192 

tridentatmn, structure of 

flower, 191 ; three forms on the 
isame plant, 196; a male orchid, 
197; vessels of, 289; peculiar 
form of rostellum, 256; nectar- 
receptacle, 269 

Citttleya, structure of flower, 143- 
148 ; vessels of, 239 ; nectary, 
265 

crispa, 147 

Caudicles of pollinia in the Vandex, 
152 ; development of, 252 ; struc- 
ture, 260, 261 

Cephalantliera. number of seeds, 277 

ensifolia, 86 

grandtflora, structure of flower, 

80-86 ; vessels, 239, 242 ; change 
of colour in viscid secretion, 249 ; 
pollen, 259 ; lubellum, 269 ; num- 
ber of seed, 277; upright position 
of flower, 287 ; partially self-fer- 
tile, 290 

Cheeseraan, Mr., on Pterostijlis 
trullifoUa, 88 ; Acianthus sin- 
cldirii, 90 ; imp rfect fertilisation 
of Fterostylis, 280 

Chijsis, 146 

Ci<-rhiea, contracted stigma, 171 



Clinandrum, the, 241 

Ccelogyne cristata, 146 

ConjantJies, 90, 173 ; nectary, 232 ; 
secretion of nectar, 2(i5 

Jieldingii, 175 

macrantha, 175 

speciosa, structure of flower, 

174 

triloba, partially self-sterile, 281 

Cruger, Dr , on the Epidendre<e, 
147; Gongora maculata, 168; 
StanJiopea, 171; Coryanthes, 173; 
C. macrantha, 175 ; Catasetum, 
197, 200 ; female polleu-mas«es, 
202 ; Selenipedium palmifoUam, 
232; homologies in Orchids, 235 ; 
bees gnawing the labellum, 270 

Cycnoches egertonianum, 224 

ventricosum, structure of flower, 

220-224 

Cymbidium giganteum, 155 : pol- 
linia, 252, 260; modification of 
form, 263 

Cypripedium, structure of flower, 
226 ; secretion from, 229 ; pollen, 
262 ; labellum, 275 

acaule, 229 

barbatum, vessels of, 239 

caJceolus, 229-231 ; fertilised 

only by small bees, 282 

candidum, 235 

pubescens, 229, 230 

piirpuratuiny vessels of, 239 

Cyrtostylis, 90 

Darwin, Francis, on the movemeut 
of the awn of Stipa, 273 

, George, insects fertilising iZer- 

minium monorchis, 61 ; Gymna- 
denia conopsea, 67 

, William, on Epipactis palustris, 

99, 100 

Delpino on insects being deceived by 
the presence of a nectary not con- 
taining neetar, 41 ; sterility of 
Spider Ophrys, 50, 51 ; Cephulan- 
thera ensifolia, 86 ; movements of 
pollinia, 155; fertilisation of C(//;r»- 
pedium calce.olus, 231 ; imi)erf(ct 
fertilisation of Ophrys arani/cra 
in Liguria, 280 

Dendrobium, length of anther, 2S7 

bigibbum, 142 

cretaceuni, 142, 291 



296 



DENDROBIUM. 



INDEX. 



HABENAKIA. 



Dendrohium chrysanthum, structure 
of, 138-142; nectary, 2G5 

formosuin, 142 

speciosum, partially sterile, 281 

tortile, 142 

Descent, lines of, 262-265 

Dickie, Prof., obligations to, 124 

Disa, secretion of nectar, 265 

cornuta, 78 

grandijiora, 77 ; partially self- 
sterile, 281 

macro ntha^ 78 ; partially self- 
fertile, 290 

Disc, viscidity of, in the Ophrese., 
43 ; in Catasetum, 190 ; double in 
the Ophrex, 254 ; of Gymnadt-nia 
conopsea, 272 

Disperis, secretion of nectar, 265 

Ducbartre, M., on Catasetum and 
Myanthus, 196 

Dver, Mr. Thiselton, obligations to, 
175 

Ejiidendrex, 142; few teed capsules 
produced, 281 

Epidendrum cochleatum, viscid se- 
cretion of, 249 

florihundum, 146; vi&cid se- 
cretion, 249 

glaucum, 146 

Epipactis, vessels of, 239 ; viscid 
iQiitter, 251 

latifolia, 100, 101; pollen, 259 ; 

lerlilised only by wasps, 282; 
use of knob f)f anther, 287 

microphylla, 102 

palustris, structure of flower, 

93-100 ; labellum. 275 

purpuratu, 1 02 

ruh,ginosa, 102 

viridifioT'i^ 102 ; self-fertile, 

291 

Epipogium gmelini, 1 03 

Eulophia viridis, 156 ; nectary of, 
269 

Evelyna, nectary of, 265 

carivata, Hi) ; vessels of, 239; 

clinandrum, 241 

Farrer, T. H., obligations to, 46; 

on Bee Ophrys, 55 ; Feristylis 

viridis, 63 
Ferlilisation, summary on. 290 
I'^ertiLty of KUj^lish Orchids iVS 



Fitzgerald, E. D., on Pterostylis 
longifolia, 89 ; Caladenia dimor- 
pha, 89 ; Acianthus fornicatus, 
and exsertus, 90 ; Vanilla aroma- 
tica, 91 ; Spiranthes australis, 1] 5 ; 
Thelyniitra Garnea and longifolia, 
127 ; numbers of Orchideee col- 
lected near Sydney, 279 ; self- 
fertilisation of Thelymitra carnea, 
280 ; Dendrohium speciosum, 281 

Flowers, use of external envelopes, 
274 

Fly Ophrys, 46 

Frog Orchis, structure of flower, 62 ; 
secretion of nectur, 63 

G' I leandra funkii, 155 

Gartner on viscid matter of stigma, 

249; pollen-grains in Orchids, 

288 
Gerard, M. INI., pollinia adhering to 

longicoru beetle, 16 
Glossodia, 237 
Gongora, labellum of, 276 

atro-purpurea, 169 

macuhita, 168 

trunC'ita, 169 

Goodyera, vessels of, 239 ; caudicle 

in a nascent condition, 260 

discolor, 105 

puhescens. 105 

repens, 103, 105 

Gordon, Kev. G., obligations to, 103 
Gosse, Mr., on self-fertilised seeds of 

Ep'dendrew, 147, 148 
Gradation of origans, 247 
Giay, Prof. Asa, on Gymnadenia 

tridentata, 68 ; Platanthera, 75 ; 

Goodyera repens, 105 ; Spiranthes 

gracilis and cernua. 111 ; Cypri- 

pedium, 229, 230, 235 
Gymnadenia, viscid matter, 251 

albida, 43, 68 

conopsea, transplanted, 32 ; se- 

cietion of nectar, -i 0, 43 ; structure 

of flower, 65 ; vessels, 238, 239 ; 

rostellum, 255; movements of 

pollinia, 271 ; disc, 272 

odoratissima, 68 

tridentata, 68; self-fertile, 291 

ITahenaria hifoJia, 78; secretion of 
nectar, 40, 43 ; viscid matter, 251 



HABENARIA. 



INDEX 



MORE. 



297 



Uabenaria ehlorantha, 43, 69 ; vessels 
of, 239, 244 ; viscidity of exterior 
surfuce, 251 

Hance, Dr., on Gatasetum, 197 

Herbert, Dean, on Catasetum luri' 
dum and Myanthus, 196 

Herminium monorchism 59 ; fertilised 
by insects, 61 ; rostelluin, 255 

Hildebrand, F., on the ovules in 
Orchids, 172 

Homologies of Orchids, 232 

Hooker, Dr., on Listera, 3, 115 ; 
lubellum of Galxna, 89; obliga- 
tions to, 115, 128, 244; spiral 
vessels in Orchids, 235; varia- 
bility of the labellum of Orchids, 
238 ; on the rostellum, 254 

Horwood, Mr., assistance from, 129 

Insects, frequency of visits to Or- 
chids, 33; attracted by bright 
colours, 275 

Irmisch on Epipogium, 103 ; Neottia 
nidus-avis, 125 ; flower-bud of Cy- 
pripedium, 240 

Kriinitz, secretion of nectar by 
Orchis, 36 

Kurr, on Orchids secreting nectar, 
38; secretion from hairs in Cy- 
pripedium calceolus, 229; nectar 
secreted from bracteae, 266 

Labellum easily vibratile, 138 ; cup 
of, not secreting nectar in the 
Vandex, 269; excrescences on, 
269 ; gnawed by insects, 270; its 
importance to the flower, 275 ; of 
Sarcanthus, 276 

Ladies' slipper, 227 

tresses, 106 

Lxlia, 146 

cinnabarina, 148 

Lepidoptera with attached poUinia, 
30,31 

Leptotes, 14b 

Lindley, Dr., obligations to, 129; 
arrangement of Orchids, 128 ; on 
forms of Catasetum, 197 ; of Cyc- 
noches, 224 ; homologies of Orchids, 
235; on the number of genera 
and species, 279 

Link on homologies of Orchids, 235, 
238 

14 



Liparis pendula, vessels of, 239; 

clinandrum, 241 
Listera, viscid matter, 251; crest 

of rostellum, 287 

cor data, 124 

ovata, structure of, 115-124; 

labellum, 276 
Lycaste skinneriij 155; pollen of 

260 

Malaxess, 128 

Malaxis, viscid matter, 251 ; upper 
petals, 276 

paludosa, transplanted, 32 ; 

structure of flower, 129-135; 
vessels, 239, 241; clinandrum, 
241; pollen-tubes, 258; position 
of labellum afi'ected by ovarium, 
284 

Maiden, Kev. B. S., obligations to, 
35,64 

Male flowers of Catasetum, 198 

Marantaceai, 238 

MarshaD, Mr., on sterility of trans- 
planted Orchids, 32; Hahenaria 
ehlorantha, 72 

Masdevallia, clinandrum of, 241 ; 
sepals, 274 ; upper petals, 276 

fenestrata, 135, 136, 142 

Maxillaria, movements of pollinia, 
156; number of pollen-grains in 
anther, 278 

ornithorhyncha, movement of 

pollinia, 157, 159 

Megaclinium falcatum, labellum of 
138 

Me'niere M., on insects visiting Or- 
chids, 30 ; secretion of nectar by 
Coryanthesj 173 ; movement of 
Catasetum, 187, 191 ; the nectar- 
receptacle, 269 

Minrostylus rhedii, 132, 135 

Miltonia clowesii, pollinia of, 154, 
155 

Modifications in Oichids, 246 

Moggridge, J. Traherne, on Ophrys 
scolopax, 52, 292 ; Ophrys apifera, 
56, 58, 59 ; flowering of the 
Ophrex, 59 

Monachanthus viridis, 196, 197, 198, 
201 

More, Mr. A. G., on fertility of Bee 
Ophrys, 55 ; Epipactis yalastris, 
39, 97, 99 ; obligations to, 106 



298 



MORMODES. 



INDEX. 



Monnodes ignea, structure of flower, 
208-219; viscid secretion, 249; 
use of labellum, 276, 283 

luxata, 219 

Morren, on Vanilla ar.tmatica, 91 

Moths with attached pollinia, 21, 
30, 31 ; intellect of, 37 

Movements of pollinia, 271 

Miiller, Fritz, on Epidendrex, 148; 
polliuium of Ornithocephalus, 159, 
IGO; Sphinx moth, 163; con- 
tracted stigma, 171, 172 ; ovules 
of Epidendrex and Vandex, 173 ; 
Catasetum mentosum, 206; brac- 
teso of the Oncidium secreting 
nectar, 266 ; labellum gnawed by 
insects 271 ; number of seeds in 
capsule of Maxillaria, 278 ; num- 
ber of Orchideae in South BrazU, 
279 ; the orchideous tribes failing 
to be fertilised, 280 ; prepotency 
of pollen, 289 

, Hermann, on fertilisation of 

Orchis mascula, 13 ; bees visiting 
the flowers of Orchis latifolia, 
16 ; Nigritella angustifolia, 27 ; 
fertilisation of Orchids, 29; in- 
sects puncturing laburnum flow- 
ers, 41 ; Gymnadenia odoratis- 
sima, 68 ; Habenaria hifolia 
and chlorantha, 74; E'pipactis 
ruhiginosa, microphylla, and viri- 
dijiora, 102 ; Neottia nidus-avis, 
125; Oypripedium calceolus, 231; 
secretion of nectar, 267 

Musk Orchis, structure of flower, 
59 

Myanthus haroatus, 192, 199, 203; 
quite sterile, 205 

Nectar, secretion of, by British 
OphreaB, 37, 39 ; in foreign Or- 
chids, 229 ; from bractese, 229 

Nectary cut off to test the intel- 
lect of moths, 37 ; length of, in 
Angrxcum sesquipedale, 265 

Neotinia intacta, 27, 291 

Neottex, 93 ; vessels of, 241 

Neottia nidus-avis, 125 ; pollen- 
tubes, 258 ; partially self-fertile, 
290 

Nevill, Lady Dorothy, oUigations 
to, 129 

Nicotiana, stigma cf, 249 



Nigritella angustifolia, 27 
Notylia, contracted stigma, 171 

Odontoglossum, 156 

Oliver, Prof., obligations to, 129 

Oncidium, pollinia, 153, 156, 158; 
vessels of, 239 ; viscidity, 251 ; 
bractese secreting nectar, 266 

unguiculatum, development of 

caudicles, 252 

Ophrex, 6 ; vessels of, 241 

Ophrys apifera, structure of flower, 
52 ; fertility of, 54-58 ; pollen, 
259 ; self-fertilisation, 279, 291 

arachnites, 51 

aranifera, 50 ; imperfect fer- 
tilisation, 280 

muscifera, transplanted, 32 ; 

structure, 45 ; fertility, 49 ; self- 
sterile, imperfectly fertilised by 
insects, 280 

scolopax, 52, 292 

Orchidex, moditications in, 246 

Orchis fuscaj 15 ; imperfect fertili- 
sation, 35 ; secretion of nectar, 37 

hircina, 25 ; nectary, 39; move- 
ment of pollinia, 273 

latifolia, 15 ; imperfect fer- 
tilisation, 35 ; secretion of nectar, 
37 ; two distinct discs, 255 

maculata, 15, 34 ; transplanted, 

32 ; imperfect fertilisation, 35 ; 
secretion of nectar, 37, 39; two 
distinct discs, 255 ; rostellum, 
255 ; number of seeds, 277. 278 ; 

Orchis mascula, structure of flowt-r, 
6; movement of pollinia, 273 ; 
number of pollen-grains, 278 

militaris, sterility of, 36 ; se- 
cretion of nectar, 37 

morio, 15, 128; fertility of, in 

cold season, 33; secretion of 
nectar, 37, 39 ; number of pollen- 
grains, 278 

pyramidalis, structure of 

flower, 16 ; movements of pollinia, 
21, 272, 273 ; fertility in diflerent 
stations, 34; secretion of nectar, 
37, 39 ; monstrous flowers, 38 ; 
single disc, 254 ; rostellum, 256 ; 
pollen-grains, 260, 261 ; contriv- 
ances for its fertilisation, 264 

ustulata, 25 

Organs, gradation of, 247 



0RXITH0CEPHALU3 



INDEX. 



Srr.ENGEL. 



299 



Oniiihocephalus, 160 
Ovai'ia of Orchids, 284 
Oxeuden, Mr. G. C, obligations to, 
25 ; ou Epipactis purpurata, 102 

Parfitt, Mr., on attached pollinia, 31 
Paiker, Mr. R., obligatious to, 129 
Pedicel of pollinium, 253 ; elasticity 

of, 283 
Percv, Dr., analysis of labellura of 

W'arrea, 270 
Veridylus viridis, secretion of nectar, 

43, 63 ; rostollnni, 255 
Petals, nsr>s of, 274 
riiaius, 146 

grandifolius, 280 

Fli(danopx,is, viscidity of stijrnia, 

153; movement of pollinia, 159; 

labellnm, 276 

amahilis, 159 

grandijiora, 150 ; projection of 

lab'ellum, 269 
riatanthera, 75 

chlorantha, 69 

dilatata, 77 

flava, 76, 77 

■ hookeri, 75 

• hyperborea, 76; self-fertile, 291 

Fleurotliallis ligulata, 135 

■ prolifera, 135 

Pogonia ophioglossoides, 86 
Poilen-massps, rudimentary in Mono- 

chanthus, 201 ; gradation of, 257, 

2S8 
Pollea-tubes emitted from anther, 

258 
Pollinia, movements of, in Orchis 

mascula, 12-15; in 0. pyrami- 

dalis, 21 ; of the Vandex, 154 ; 

of Catasetum, ejection of, 184; 

attachment to rostellum, 251 ; 

gradation, 2.i7; movements, 271 
f'terostylis, nectary of, 232 

longiflora, 87, 89 

trullifolia 86, 88 ; imperfect 

fertilisation in New Zealand, 280 

Rodger?, Mr., obligations to, 129 ; 
on Myanthus and Monochanthus, 
196 ; tecretion of nectar in Or- 
chids, 265 ; in Vanilla, 266 

liodrignezia secunda, 159 

suavcolens, m<»vemcnt of pol- 
linia, 156, 159 



Rohrbadi, Dr., on Epipogium gmc' 
lini, 103 

Rostellum, a single organ in the 
OphrecB, 45 ; of the Vandex, 
150; aborted, 242; gradation of, 
247 ; of Apostasia, 248 ; diversity 
of structure, 250 ; crest of, in 
the Ophrex, 255 ; in Catasetum, 
256 

Rucker, Mr., obligations to. 129, 
ISO, 192, 208 

Saccolahium, viscidity of stigma, 

153, 156 
Saint-Hilaire, A. de, on pollen of 

Orchids. 259 
Sarcanthus, labellura of, 276 

parishii, 142 

teretif alius, pollinia of, 154, 

156; viscidity, 268 
Scheinsafthlunien, 37 
Schomburgk, Sir R., on Catasetum, 

196 
Scott, Mr., on flowers of Acropera, 

168, 172 ; of Gongora, 169 ; nec- 

tor-receptacle, 269; number of 

seeds in capsule of Acropiera, 278 ; 

prepotency of pollen. 289 
Scudder, Mr., on Fogonia ophio- 
glossoides, 86 
Secretion of nectar, 36, 229, 265 
Seeds, production and number of, 

276, 277 
Selenipedium palmifolium, 232 
Self-fertilisation, summary on, 293 
Sepals, uses of, 274 
Serapias cor dig era, 27 
Sexes of Orchids, 196 
Smith, Sir James, on position of 

flowers in Malaxis, 1 29 
, Mr. G. E., on bees visiting 

the Bee Oplirys, 55 
Sohralia macrantha, 91 
Sophronitis, 146 
Spider Ophrys, 50 
Spiranthes audralis, 114; labellnm, 

275 ; self-fertile, 291 
autumvalis, structure of flower, 

106-114 ; vessels of, 239 

cermca, 111 

gracilis. 111 

Sprengel, C. K., on fertilisation of 

Orchis miliiaris, 36 ; secretion 

of nectar by Orchis, 36 ; on Epi- 



300 



(STAMENS. 



INDEX. 



ZTGOPETM.DM. 



pactis latifolia, 101; Lister a^ 
115, 123 ; colours attracting in- 
sects, 275; value of his work, 
275 

Stameus in Orchids, 242 

Stanhopea, pollinia of, 155; label- 
lum, 276 

devoniensis, 171 

oculata^ 171 

Stelis, use of the sepals, 274 

racemijlora, 135 

Stei ility of English Orchids, 35 

Stigma, viscidity of, in the Vandex, 
152; utriculi, 197; gradiitiou, 
248 ; structure, 249 

Stipa, movements of, 273 

Structure, diversity of, 282, 285 

Structure, importance of trifling 
details, 286, 287 

Thehjmitra, self-fertile, 291 

carnea, 127; self-fertile, 280 

longijiora, 127 

Thomson, R. B., on Goodyera 

repens, 105 
Tilley, H. A., on Vanilla aromatica, 

91 
Trevelyan, Sir C, on Bombtts with 

attached pollen-masses from Catt- 

leya, 145 
Treviranus on the secretion of 

nectar, 41 ; on Bee Oplirys, 56 
friraen, R., obligations to, 40 ; on 

Bonatea speciosa, 76, 77 , Lfisa 

grandiflara, 77, 78 



Turnbull, Mr., obligations to, 129 
T way-blade, 115 

Uropedkim, 240 

UtricuU of stigma, 197, 218 

Vandex, 156 

, structure of, 149; pollinia, 

253. 258 
Vanilla aromatica, 90 
VamlUdex, 90 ; few seed capsules 

produced, 281 
Veitch, Mr. J., obligations to, 129, 

180, 220 
Vessels, spiral, of Orchids, 235 
Viscidity of disc in British Ophreoo, 

35 ; in Catasetum, 190 
of rostellum and stigma, 248, 

249 

Waetcher on fertilisation of the 
Orchids, 2 

Walker, Mr. F., obligations to, 100 

Wallis, Mr., obligations to, 129 

Warrea, 155 ; analysis of labellura, 
270 

Weale, J. Mansell, on Habenaria, 
76 ; Bonatea, 77 ; Disa and Vis- 
peris, IS; Disa macrantha, 2[)i) 

Weddell, Dr., on hvbrids of Aceras, 
26 

Wright, Mr. C, on the movement 
of pollinia, 156 

Zygopetalum mackaiy 155 



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