THE
International Scientific Series
VOL. LXXXVI.
KECENT ADDITIONS
TO THE
NTERNATIONAL SCIENTIFIC SERIES.
By Sir John Lubbock.
ON BUDS AND STIPULES. By the Eight Hon.
Sir Johx Lubbock, Bart., M.P., F.R.S., is,
&c, these also perish, and as a rule only the lower ones
grow, and the upper part of the stem dies back.
The arrangement of the leaf in the bud influences,
and sometimes determines, the form of the leaf.
This consideration explains, I think, the curious
fact that the first leaves, or cotyledons, often, indeed
generally, differ altogether in shape from the true
leaves. They offer an immense variety of form ; not
quite so innumerable, indeed, as those of true leaves, of
which Linnaeus truly observed ' that ' Natura in nulla
parte magis fuit polymorph a quam in foliis,' but still
immense. They may be large or small, broad or
narrow, entire or much divided.
Now, why should the first leaves differ so much
from their successors ? The reason, I believe, is that
while the forms of leaves often depend greatly on the
1 Philosophia Botanica.
ON BUDS
11
buds, those of cotyledons are even more often influ-
enced by the shape of the seeds. Let me give two
instances in illustration.
I will take first the Common Radish (Raphanus
sat ivus), with which, as regards the cotyledons, the Cab-
bage and Mustard closely agree. The seed of the Radish
is shaped as in fig. 12. What regulates the shape
o
FlOB. 12-14. — Uadisii (Tictjihanus sativiis).
18, outline of seed, x 4 : nmnicropyle; A,hilam ; 13, embryo in vertical section, x4.
showing the folded cotyledons and root (r) lying between them; 1 i
Dating seedling, showing the cotyledons still folded, x 2.
of the seed is another question, into which I will not
now enter. The young plant, consisting of two leaves,
a small root, and a minute bud, occupies the whole
interior of the seed. Each leaf is folded on itself like
12 BUDS AND STIPULES
a sheet of notepaper, and one lies inside the other.
To this folding the emargination is due. If a piece of
paper betaken, folded on itself, cut into the form shown
in fig. 12. with the fold along the edge from m to //,
and then unfolded, the reason for the form of the coty-
ledons becomes clear at once.
Now let us test this ex-
planation by another case. The
Wallflower has a seed of similar
shape to that of the Radish,
though thinner. Now, are the
cotyledons of the same form
as in the Mustard or Radish ?
Not at all. Those of the Mus-
tard, as we have seen, are kid-
ney-shaped ; those of the Wall-
flower are racket-shaped, as in
fig. 15. At first this seems a
Fig. 15.— Seedling of Wall- °
flower. Two thirds nat. difficulty ; but on looking closer
the difficulty vanishes, for while
the cotyledons of the Mustard are folded, this is not the
case with those of the Wallflower, which lie flat in, and
conform to the shape of, the seed, as shown in fig. 16.
Thus the difference, which at first sight seemed a
difficulty, is really a confirmation of the explanation
suggested.
But we may even carry the matter a step farther.
Why are the cotyledons of the Radish folded, and not
ON BUDS 13
those of the Wallflower ? Because, as I have already
mentioned, the seeds of the Wallflower are thinner than
those of the Mustard, so that there would not be room
for the four folds of the doubled leaves.1
In illustration of the influence which the form of
the bud exercises on the shape of the leaf I may refer
to my paper in the ' Contemporary Review ' for May,
1885, to several memoirs in the ' Journal of the Linnean
Society,' and to my book on ' Fruits, Flowers, and
Fig. 16.— Sections of Seed of Wallflower. Transverse
(left) x 10, and longitudinal (right) x 22.
/;. radicle : (', cotyledon.
Leaves.' I will here only mention one or two cases.
The leaves of the Tulip Tree (Liriodendron tulipifera)
have long attracted attention from the peculiarity of
their form. They are saddle-shaped, abruptly truncate
at the end ; or, in the words of Bentham and Hooker,
1 sinuato-4-loba.' I long wondered what could be the
purpose or the advantage to the tree of this remarkable
1 This interesting subject is dealt with more fully in my book on
Seedlings.
14
BUDS AND STIPULES
shape. One idea which occurred to me was that the
difference of form might enable insects to perceive the
tree at some distance, just as the colours of flowers are
an advantage in rendering them more conspicuous. I
then looked closely to see whether the peculiar forms
could in any way be explained by the position of the
leaves on the tree. I believe, however, that the cause
is of a different nature, and has
reference to the peculiar character
of the bud.
Each young leaf is, as in the
family Magnoliacete generally, ori-
ginally enclosed in and sheltered
by the stipules of its predeces-
sor. These are in Liriodendmn.
oval, or in form resembling a
shallow dish or spoon, so that
when placed face to face they
form a hollow almond-shaped
box. Inside this lies the next
younger pair of stipules; and the rest of the space is occu-
pied by the young leaf, which is conduplicate, or folded
on itself down the middle, like a sheet of notepaper, and
also turned back towards the base of the bud. This
unusual position is probably due to the early develop-
ment of the petiole. The young stages in the develop-
ment of the leaf are shown in figs. 17 and 18.
Here it seems obvious that the peculiar form of the
Fig. 17. — Diagram show-
ing Arrangement of
the Young Leaf of
LlRIODENDRON.
ON BUDS
15
leaf is due to the form and arrangement of the
bud.
M. Emery l has made some criticisms on my sugges-
tions, which, however, I need not notice, for, having
merely seen a short and incorrect abstract, and not having
taken the trouble to refer to the original paper, he mis-
understood my view, as M. Devaux pointed out at the
Fig. 18. — Arrangement of Young Leaves op Liriodendron.
A corresponds with leaf No. 6 in C ; fi, next younger leaf ; G, ground-plan of
a bud, showing successive leaves (1 -7), with stipules (7 5, &c.)
time. I should gather also from his remarks that he
can never have examined a bud in a very early state.
Or take, again, the case of the Oak and Beech. Both
have a conical bud, and the young leaves are protected
by stipules. I shall presently refer to them again
from this point of view. For the moment I am dealing
Bull. Soc. Bot. France, 1888, p. 327.
16
BUDS AND STIPULES
with the form of the leaf only. In botli species the
leaves, like those of Linodendron, are conduplicate.
The leaves are in both species of about equal length,
or those of the Oak are the longer ; but the buds of the
1
Fig. 20.— Oak Bud, x 6.
Beech (fig. 19) are much longer than those of the Oak
(fig. 20). The young leaves of the Beech are able to
lie straight in the bud ; those of the Oak have not
room to do so, and are, consequently, bent somewhat
like a bow along the midrib. Now, if the outer edge
ON BUDS 17
were straight, the result would be that when the young
leaf emerged and straightened itself the edge must
tear. This, however, is avoided by its being thrown
into folds ; and this, I believe, accounts for the lobes
and bays so characteristic of the Oak leaf.
Dormant and Adventive Buds
As a rule each leaf has a single bud in its axil ; but
there are two other classes of buds about which I must
say a few words. In some species not merely one, but
several buds arise in the axil . They appear to have been
first noticed by Tristan (3). In such cases as, for in-
stance, the Robinia (' Acacia ') all but one of these, after
attaining a certain stage of growth, become quiescent,
and are gradually covered over by the bark. Such
buds are known as ' dormant.' They may remain in
the same state for years, but if the growing shoots are
injured in the struggle for existence these reserves are
called into the^ field. Their presence is often connected
with that of thorns, as in Robinia, Gleditschia, Colletia,
Genista, &c. ; or with tendrils, as in Passiflora.
Another class of buds has been termed by Du
Petit Thouars ' adventive ' buds. They appear, especially
in certain plants, on the leaves, internodes, and roots.
They may be divided into two classes — natural and
accidental.
Natural adventive buds are formed by Gardamine
I'l'tifcnsis, Bentaria bidbifera, Bryop/iyllum calycimim,
c
18 BUDS AND STIPULES
a considerable number of Dicotyledonous and Mono-
cotyledonous plants, and many ferns.
A common example occurs in any abandoned field
or waste ground bordered by Elm trees. The young
plants which shoot up everywhere are not seedlings, but
are formed by adventitious buds on the roots of the old
trees ; the considerable distance at which they appear
from the parent emphasises the great length of the
roots. Similarly, when a tree is cut down the ground
becomes covered with a thick growth of young shoots,
springing up rapidly, at the expense of the nourish-
ment stored up in the roots which remain in the
ground. Such shoots are also common in Poplars,
Limes, many fruit trees, &c.
Accidental adventive buds are those which appear
if the plant is maimed or wounded ; or if a leaf, say of
Begonia, is detached from the parent plant and placed
on damp earth.
Goebel, in his recently published ' Organographies
figures an interesting case of the growth of a new
plant at the end of the stalk of a detached leaf. The
plant in question is a garden hybrid belonging to the
same family as Gloxinia (fig. 21). The leaf was taken
from a plant which was just about to flower, and the
adventitious shoot has straightway produced flowers.
To eradicate Docks from a garden the whole plant
must be removed, as adventitious buds will arise on
any broken piece of root which is left behind The same
ON BUDS
19
applies to Dandelions or Plantains. The natural
adventive buds appear on definite parts of the plant,
according to the species ; in accidental adventive buds
the place of origin depends on that of the injury.
Fig. 21. — Achimenes Haagkaxa. showing development of a new
flowering plant consisting of root and flowering-shoot.
Adventitive shoots may arise, like normal shoots,
exogenously ; but endogenous development generally
occurs when they arise from older parts of stems or
roots. In some cases they are formed by the direct con-
version of the growing-point of a root, as in Bird's Nest
Orchid (Neottia Nidus-Avis), Catasetivm bridenkitwn, &c.
c2
20
iiUUS AMJ sTll'i LE3
CHAPTER II
ON STIPULES
Vaucher, in his ' Histoire Physiologique des Plantes/
writing on the Rock Roses (Helianthemum), observes :
Fig. 22. -Shoot of Helianthemum vulgare. Slightly enlarged.
; J'indique dans ce genre deux principaux objets de
recherche. Le premier est la raison pour laquelle
certaines especes out des stipules tandis que d'autres
ON STIPULES 21
en sont privees.' This suggestion started me on
the present inquiry. No one, so far as I know,
had attempted to answer Vaucher's question, which
is one of considerable interest, and might be asked
with reference to several other groups besides the
genus Helianthemum. The results of my observations
have been embodied in several Memoirs which the
Linnean Society has done me the honour to publish in
their ' Journal,' and I now propose to bring together
those portions which seem to be of general interest.
Fig. 23. — Shoot of Helianthemum celandicum. Slightly enlarged.
Fig. 22 represents a shoot of Helianthemum vulgar e
(the Common Rock Rose), with stipules ; Fig. 23, one of
HeliantJiemum oelandicum, which has none.
Malpighi, in his ' Anatomy of Plants ' (1671), seems
to have been the first who mentions these organs, which
he terms (p. 29) 'folia caduca,' in opposition to the ordi-
nary and generally, though by no means always, more
permanent leaf-blades. Almost at the same time (1672)
they were noticed and described by our countryman
Grew, who called them interfoils.1 Linnasus gave them
1 The Anatomy of Plants, p. 146.
22
BUDS AND STIPULES
the name of stipules ; from stipula, a little straw. This
term happily expresses their appearance in such a case
as that of the Beech, but they present great differences
in size, form, and texture.
Fig. 24. — Leaf of Peach.
Two-thirds nat. size.
St, stipules ; b, axillary bud.
Fig. 25. — Leaf of Portugal
Laurel. One-third nat. size.
St, St, stipules.
The Peach (fig. 24) and Portugal Laurel (fig. 25) are
good examples of a typical simple leaf with a pair of
stipules at the base of the stalk.
ON STIPULES
23
Stipules present, however, a great variety of forms.
Those, for instance, of the Common Garden Pea
N
rn
i
* is
Fig. 26.— Stipules op Pea before the unfolding of the Leaf.
A, natural position ; B, one stipule turned back, showing the rest of the leaf.
(Pisum sativum) (fig. 26) are
large, oblong-oval, mucronate,
unequal - sided, and unequally
toothed at one side. They cover
the rest of their own leaf in the
young stage and all the rest
of the bud.
In the Pansy (fig. 27) they
are large, oblong, and pinnatifid,
with 3-6 linear lobes on the ex-
ternal side.
In Hym&narUh&ra (fig. 28), a
Fig. 27.— Leaf of Pansy
Three-fourths nat. size.
S, S, stipules.
24
BUDS AND STIPULES
shrub also belonging to the family of the Violets, the
stipules are small.
Fig. 29. -Young Shoot of
Holly. Nat. size.
l', I", l'", successive leave- ;
st, st, stipule.-:.
Fig. 28. — Shoot of Hymenanthera
crassifolia, x 2.
In other cases stipules are even more minute, as in
the Holly (Ilex Aquifolium) (fig. 29). Here they are
perhaps functionless ; the mere rudiments of once larger
organs.
ON STIPULES
25
In other cases, however, as for instance in Guaiacum
officinale (fig. 30), though the stipules are small, still they
afford a very efficient protection to the minute bud.
For other illustrations of bud-protection by stipules,
see Plate I. figs. 1 and 2, the Lime ; figs. 4 and 5, the
Hornbeam ; Plate III., the Wych Elm ; and Plate IV.,
the Beech.
Fig. 30. — Guaiacum officinale.
A. Terminal shoot, nat. size : n, node ; it', connate stipules ; it", connate stipules
covering the terminal bud.
15. Terminal shoot with hiuiina of leaves removed, x2; it', it", stipules as in A :
b, lateral bud.
Stipules are sometimes situated on the leaf-base,
sometimes at the foot of the leaf-base, sometimes
on the stem just below the leaf-base.
In the Dwarf Elder (Sambucus Ebulus) they are
26
BUDS AND STIPULES
comparatively large ; while in the Common Elder (Sam-
bucus nigra, fig. 31) they are minute or altogether absent.
«vfe. ^^ In many cases the stip-
^^^^^^^^^^sc llles differ in shape and
size, even in the same
plant. Of this the Common
Thorn (Ora&cegus Oxyacan-
tha) (fig. 32) affords a good
illustration.
As regards their colour,
leafy stipules are generally
green ; the minute stipules
of the Holly (Ilex Aquifo-
lium) are black ; the scales
of buds are various shades of
brown, shading off to white ;
scarious stipules range from straw-colour to grey. Some
are beautifully coloured, almost like the petals of flowers :
in the Hornbeam, for instance, often of a bluish purple
(PL I. figs. 4 and 5) ; and in the Wych Elm (PI. III.)
a red purple; in the Lime a rich crimson, or even
bright ruby (PL I. figs. 1-3).
Stipules, when large and foliaceous, resemble in tex-
ture the leaves of which they form a part. The outer
stipular scales of many buds are tough and leathery, the
inner ones more membranous, and often very delicate,
thin, and almost transparent. Others develop into hard,
woody spines, as in Robinia (so-called Acacia), &c.
(figs. 33, 34).
Fig. 31. — Youno Shoot of
Elder (Savibucus nigra).
ON STIPULES
27
As regards the duration of life, some stipules, such
as those of the Beech, Oak, Elm, &c, which only serve
to protect the young leaves, drop off as soon as the
Fig. 32. — Five Leaves of the Common Thorn. Nat. size.
St, stipules, absent in the first figure.
latter expand. The ground under Beeches in spring is
almost brown with fallen stipules.
28
BUDS AND STIPULES
Others, as, for instance, those of the. Pea, Pansy,
Bedstraw, &c, which assist in performing the ordinary
function of leaves, live as long as, and drop with, the
leaves to which they belong.
Lastly, there are some, though they are exceptional,
which survive the rest of the leaf and protect the next
succeeding bud, as, for instance, in Petteria (figs. 35,
36) ; or they may last indefinitely, as in Robinia.
Fig. 33. — Robinia viscosa.
size.
Nat.
s, s, spiny stipules sketched in winter
(Jan." 25, 1897) ; sc, scar of fallen
leaf ; g, gland above the bud.
Fig. 34. — Robinia Pseudacacia,
var. Decaisneaxa. Nat. size.
*, s, spiny stipules sketched in winter
(March 13, 1897) ; sc, scar of fallen
leaf ; g, gland above the bud.
In certain cases most of the stipules of a species are
caducous, while some of them are persistent.
Thus, in the Black Poplar (Populus nigra), (fig. 37)
the stipules of the upper leaf often survive the leaf-
blade, which drops off in autumn, while they retain
their place and protect the young bud through the
winter.
ON STIPULES
29
When stipules survive the rest of the leaf to which
they belong, this generally has reference to the protec-
tion of the buds. Thus, in Magnolia Umbrella the
leaf terminating each year's growth is small, and
eventually the blade becomes disarticulated just above
the stipules, which are adnate to the leaf-base and
enclose the bud (fig. 38). These stipules are in this
species the only ones which survive the leaf-blade.
Fig. 35. Fig. 36.
Pettekia ramentacea.
Fj<;. 35.— Portion of shoot in winter, x 2.
In;. :itj.— Ditto in spring, x2. Sc, scar
of fallen leaf; St, stipules completely
covering the bud in fig. 86, in fig. 36
pushed aside by the developing bud (b).
Fig. 37. — Populus nigra.
Terminal Winter-Bud,
showing a pair of per-
sistent stipules (st) be-
longing to a leaf of last
season, x 2.
Some other species of Magnolia — for instance, a
garden hybrid, M. Soulangiana — agree with If. Umbrella
in these respects.
In some cases, however, as in the so-called Acacia
(Eobinia), the thorny stipules assist in the protection of
the plant as a whole.
30
BUDS AND STIPULES
h—
Fig. 38. — Magnolia Umbrella, showing disarticulation of the leaf-
stalk above the stipules, which are wrapped round the terminal bud.
Before and after the fall of the leaf.
p, pedestal or persistent base of petiole.
Fig. 39.
Fig. 40.
Portion of Shoot or Astragalus chtnexsis, showing stipules (St)
connate at the base. Nat. size.
Fig. 39.— Front view. Fig. 40.— Side view. Two leaflets of the compound leaf
are shown.
ox stiim u;>
31
Where stipules are present the leaf has two, one on
each side. Sometimes, however, the two stipules are
connate, i.e., have grown together. This may take place
on the outside of the leaf, and be either confined to the
base, as in a Chinese Astragalus (Astragalus chinensis),
(figs. 39, 40), or continue for the greater part of their
length, as in Hedysarum esculentum (figs. 41, 42), where
Fig. 41.
Fig. 42
Hedysarum esculentum. Nat. size.
Fig. 41. Apex of growing shoot, showing ride view of stipules; i/, youngest,
partly expanded leaf, with the lowest pair of leaflets still folded, and the sti-
pules, .si', connate opposite the leaf-base ; i/', next younger leaf pushing out of
the bud with its stipules, st".
Fig. 42.— The same showing the dorsal aspect of the connate stipules, J*'.
they are reddish brown and membranous, and develop
early, so that the leaves at this stage lie between two
rows of stipules. In Sainfoin (Onobrychis sativa) (figs.
43, 44) also the stipules are united for the greater part
of their length. In other species they are ' intrapetiolar,'
more or less connate on the axillary side of the leaf, as in
the Pondweed (Fotamogeton) (fig. 45) and in the Knot-
weeds (Polygonum) (fig. 46), where they form the sheath,
called technically an beret*.
32
BUDS AND STIPULES
The Hop also has connate stipules, but in this case
the two which have coalesced belong to two opposite
leaves (figs. 47, 48). Such stipules are termed ' inter-
petiolar.'
Fig. 43.
Fig. 44.
Onobbychis sativa, showing stipules (St) united for the greater
part of their length.
Fig. 43.— Side view. Fig. 44.— Back view. P, leaf -stalk ; FL, a flower-bud.
In Spergularia (fig. 135, p. 88) the stipules are free
from the leaves, but connate at the base, forming a
sheath, which envelops the base of the leaves.
De Candolle observes that the existence of stipules
ON STIPULES
33
' parait liee assez intimement avec la symetrie generale
des plantes, car elles existent ou-manquent dans toutes
les especes d'une famille : ainsi, on trouve des stipules
dans les Rubiacees, les Malvacees, les Amentacees, les
Legtimineuses, les Rosacees, etc., et elles manquent
dans toutes les Caryophyllees, les Myrtacees, &c.'
Fig. 45. — Potamogeton luckns,
showing intrapetiolar stipules.
Fig. 46.— Polygonum, showing
Ocrea (o).
This, however, is not so general a truth as De
Candolle imagined. The absence of stipules is not com-
plete in either of the families mentioned by him. They
occur not only in Spergula and Spergularia, which are
now generally considered as belonging to the Caryo-
j>/n/l(ace«> (though certain botanists regard them as con-
34
BUDS AND STIPULES
stituting a separate family), but also in most of the
Polycarpete ; and among the Myrtacece in Calytlirix,
Couroupita, and perhaps in some other genera.
Among other families some genera of which have
stipules, while others are exstipulate, may be mentioned
Fig. 47. — End of Shoot of
Hop, x 3, showing connate
stipules (St).
Fig. 48. — End of Shoot of Hop.
Nat. size.
St, connate stipules folded back to show the
pair of leaves (l) to which they belong ;
b, axillary buds ; St2, next higher pair of
stipules, overlapping by their edges along
the median line of the axis, and with
the next higher pair (St3) covering the
terminal bud.
the Onagrariece, Saxifragece, Gercmiacete, Leguminosce,
Sapindaeece, and Etqthorbiacece. Moreover, as pointed
out in the above passage from Vaucher, there are even
certain genera — and in addition to Helianihemnm I
ON STIPULES 35
might mention Lathyms, Ge7iista, Passiflora, Acacia,
Spircea, Saxifraga, Rosa, Berberis, &c. — in which some
species have stipules while others have none.
While, then, in most families of plants the species
are all either stipulate or exstipulate, there are a good
ln.i ny families in which the genera differ in this respect ;
some genera in which the species differ ; and, lastly,
there are some cases, even within the limits of a single
species, in which certain leaves are said to develop
stipules, and others to be exstipulate, as for instance
Helianthemum guttatum, Ipomcea pendula,1 Exochorda
Albertij &c.
Let us now return to Vaucher's problem — Why
should some species of Helianthemum have stipules, and
others not? — and see whether we can find the answer
to it.
Our common Helianthemum (H. vulgare) has stip-
ules ; so have II. yolifolium, H. tomentosum, H. cegyp-
tiacum, H. rhodanthum, H. ciliare, H. lauandulcefolium,
and H. rosmarinifolium. On the other hand, there are
a number of species which have no stipules : H. oelandi-
cum, H, lasianthum, II. ocymoides, H. formosum, H.
Libanotis, and others. Now, in JET. oelandicum (fig. 23)
the plant is dwarf and prostrate ; the leaves are opposite,
oblanceolate or spathulate, tapering to a broad base,
sessile, ciliate, especially at the base, which also widens
so as closely to sheathe the young bud, thus effectually
1 Choisy, in De Candolle's Prodromus, ix. p, 387.
d2
36 BUDS AND STIPULES
protecting it. So, also, in the other exstipulate species
the leaf-stalks are all more or less widened at the base,
and the bnd is thus protected.
On the other hand, our common Helianthemum (II.
vulgare) (fig. 22) has the leaf-stalk narrowed at the base,
and glabrous or nearly so. The bud, therefore, would
be exposed if it were not for the stipules. So, also, in
the other species which have stipules the leaf-stalks are
narrowed at the base, and the buds are protected by the
stipules.
Hence we have a very strong presumption that the
answer to Vaucher's problem is that some species of
Helianthemum have stipules in order to protect the
buds ; and that in others, where this function is per-
formed by the dilated bases of the leaf-stalk, stipules
would be unnecessary, and do not occur.
Helianthemum guttatum is particularly interesting
in this respect. The upper leaves have stipules, while
the lower ones have none. Now the lower leaves have
broad leaf-bases, which effectually protect the bud, and
they are exstipulate; the upper leaves, on the contrary,
are narrow at the base, but they are provided with
stipules.
The reason for the presence or absence of stipules
seems, then, quite obvious, so far as the Rock Roses
(Helianthemum) are concerned.
Let us now see whether the conformation of other
species supports this view. In the allied genus Cistus,
ON STIPULES
37
which has no stipules, the petiole is always widened as
in the species of Helianthemum without stipules.
This is shown, for instance, in the following figure
of Cistus cyprius (fig. 49).
In CHstuB nnjinatiis (fig. 50) the petioles are connate
for some distance, so as to form a sheath.
It may, however, be objected that this is hardly a
case in point, because none of the species of Cistus have
stipules, and the petioles are all widened at the base.
Fig. 49. — Shoot of Cistus cyphius. Reduced one-half.
S, i. -Leaf of Exochorda grand ifiora^ nat. size.
Fi<:. (3. Transverse section of petiole at 3 mm. from base, x 12 ; US, upper
surface ; W, win jr.
Fk;. 58. — Leaf of Kxoehorda .\/!>,r/i, nat. size ; St, stipule.
Fie. 54.- Transverse section of petiole at 3 mm. from base, xl2; US, upper surface.
ence of stipules. The petiole of the lower leaves also
sometimes shows short teeth at its upper end, which
also probably represent the last trace of stipules.
40 BUDS AND STIPULES
Among the Magnoliaceai, some genera have stipules,
while in others they are entirely absent. In Dnmys
Winteri, for instance, they are replaced by some of the
outer leaves of the resting bud, which are reduced to
bract-like fleshy scales. The leaves are convolute, the
lower enclosing the upper ones.
Again, in Kadsura (K. japonica) the winter-buds
are protected by the outer leaves, which are reduced to
scales, and appear to consist of flattened petioles, with
a membranous margin representing stipules, free only
at the tip. The true leaves follow the scales abruptly.
Another very interesting case is that of Viburnum.1
We have in this country two wild species of this
genus — one, Viburnum Lantana (usually known as the
Wayfariug Tree) (fig. ob) ; the other, Viburnum Opulus
(fig. 56). They are not rare in woods, especially in
chalky districts ; but, though very nearly allied, their
leaves are remarkably different. I extract the following
descriptions from Syme.2
Of V. Opulus he says : ' Leaves deciduous, stalked,
roundish in outline, three-lobed, with the lobes acu-
minate, coarsely toothed and ciliated, finely pubescent,
but not furfuraceous beneath. Petioles with adnate
stipuliform appendages in the form of one (or some-
times two) linear process on each side, a little above
1 This is taken from a paper read by me before the Linnean
Society on February 20, 1890 (Journ. Linn. Soc. xxviii. p. 244).
2 In Sowerby's English Botany, 3rd ed. iv. pp. 202 and 203.
ON STIPULES
41
the base.' There are, I may add, two or more honey-
glands at the base of the lamina of the leaf.
Of V. Lantana he says : ' Leaves very shortly
stalked, without stipules, ovate-oval or elliptical-oval,
dentate-serrulate, deciduous, rugose, furfuraceous-
pubescent beneath, especially on the veins, at length
nearly glabrous.' There are no honey-glands.
Fig. 55. — Viburnum Lantana.
Fig. 56. — Viburnum Opulus.
No attempt, so far as I know, has been made to
account for the difference in form of the leaf in species
so nearly allied ; for the presence of the honey-glands
in the one and not in the other ; nor to explain the
reason for the existence of the peculiar filiform stipuli-
form appendages, nothing exactly resembling which
occurs in any of our other forest trees, the nearest
42 BUDS AND STIPULES
approach being in the allied genus Sambucus. The
presence of stipules in Viburnum would be the more
remarkable, as in the family Caprifoliacea}, to which
the Viburnums belong, stipules (if they be stipules) are
confined to this genus, to Pentajyyxis, and to Sambucus.
According to De Candolle's ' Prodromus,' there are
forty-one species of Viburnum ; and though some more
must now be added, this would not materially affect the
question. Of these forty- one, thirty-five have the leaves
entire, and more or less resembling those of V. Lantana.
None of these possess stipules. The other six have
lobed leaves, more or less like those of V. Opulus, and
these all have stipuliform appendages, the existence of
which would seem, therefore, to be connected with the
presence of the lobes.
The existence of honey-glands at the base of the
leaf is also, perhaps, connected with the texture of the
leaf.
In V. Lantana the covering of felted hairs affords a
sufficient protection ; but the tender young leaves of
V. Opulus would afford a tempting food to many cater-
pillars and other insects. The ants and wasps which
are attracted by the honey would tend to keep them
down, and thus to serve as a bodyguard. Indeed, it
has appeared to me that on specimens of V. Ojiulus,
which are much frequented by wasps and ants, the
leaves are less eaten than in other cases where they are
not so protected.
ON STIPULES 43
I now come to the stipuliform appendages. These
often bear honey-glands, bnt by no means always, and
even where these occur there seems no reason why
they should be situated on filiform appendages. On
the whole, then, I doubt whether they can be explained
as mere honey-glands, or whether, indeed, they are of
any actual use when the leaves are fully developed.
When we meet with a small organ which appears
to have no definite function, we naturally ask ourselves
whether it is the disappearing relic of some larger
organ which at one time performed some useful pur-
pose in the economy of the animal or plant. This
suggestion, however, seems untenable in the present
case, because, as a matter of fact, we do not find that
the stipuliform appendages are more developed in any
of the species allied to V. Opulus.
There is, however, a physical cause to which, per-
haps, the presence of these organs may be due. We
have seen that much the larger number. of species of
Viburnum have entire leaves, more or less oval or
ovate. This would appear to be the form typical or
original to the genus.
Now let us suppose that, either from having extended
northwards (and both Viburnum Lantana and V. Opulus
are among the northern representatives of the genus),
or from some other cause, the young leaves require
additional protection. This may be effected in several
ways. For instance, the young leaf may be guarded
44
BUDS AND STIPULES
by a thick coat of felted hairs ; this is the case in
V. Lantana. Another plan would be that the outer
leaves should become leathery, and thus protect the
inner ones ; this is the case with V. Opulus. But that
being so, it is an advantage that the inner or true
leaves should be folded, because they thus occupy less
space. This, perhaps, accounts for the folding of the
leaves of V. Opulus in the bud, while
the lobes follow from the mode in which
the leaves are folded. Now a leaf folded
up, as are those of V. Opulus, requires
only two or three lateral veins. The
remaining veins, then, and the mem-
brane connecting them, will gradually
be reduced, and ultimately disappear.
In V. Opulus, as is shown in the
figure (fig. 57), there is a space left be-
Viburnum Opu- tween the bases of the leaves. In the
L, Tlltert; lobes of S™™ **' """^ SPedeS °f wMch
ISxt yoimger pair have leaves somewhat resembling those
i>uie.aves ' Sf' st " of V. Opulus, this space is fully oc-
cupied by the following pair of leaves. This, how-
ever is not the case in V. Opulus, and the space thus
left unoccupied is filled up by the stipuliform append-
ages. I may also observe that the stipuliform append-
ages resemble leaf- lobes in being slightly conduplicate.
These considerations seem to throw some light on
the differences between the leaves of Viburnum Lantana
ON STIPULES 45
and V. Opulus — the hairiness of the former and the
smoothness of the latter ; on the lobed form of the
leaf in the latter ; and, lastly, oh the presence of the
honey-glands and the peculiar stipuliform appendages
in V. Opulus, neither of which occur in V. Lantana.
In support of the above suggestions I may refer
to the interesting analogy afforded — in a totally
different family — by the genus Spircea. Here we find
some species with entire, some with pinnate leaves ;
while those of 8. opulifolia, as the name denotes, closely
resemble those of Viburnum Opulus. Now the entire-
leaved species of Sprircea, like those of Viburnum, have
no stipules ; while Spiraea opulifolia agrees with Vibur-
num Opulus not only in the shape of the leaves, but in
the mode of folding in the bud. and also in the presence
of subulate, acuminate, stipuliform appendages.
I might give other cases, but the above will, I
think, be sufficient. It seems clear that the answer
which we had provisionally arrived at from a study of the
Hock Roses is fully borne out by the examination of other
families, and that when the bud needs protection and
the petiole is narrowed, this function is performed by
the stipules ; while, when there are no stipules, the
bud is protected in some other way, and generally by
the widened base of the leaf-stalk.
But though the protection of the bud is the general,
it is, as we shall presently see, by no means the only
function which stipules perform in the economy of plants.
46 BUDS AND STIPULES
CHAPTER III
ON THE DEVELOPMENT OF LEAVES AND STIPULES
In order to arrive at a satisfactory view as to the
structure and arrangement of buds it is necessary to
study the development of the leaf. Steinheil (4), in 1837,
was the first who approached the consideration of the
subject in this rational manner; and we are also in-
B
$
a At
Fig. 58. — Growing-point and Beginning of First Leaf of Boss.
Highly magnified.
S, apex of growing-point ; B, youngest leaf ; R, cortex ; i/, pith.
debted for excellent memoirs and observations to De
Mercklin (5) in 1846, Trecul (6) in 1853, Schacht (7) in
1854, Eichler (8) in 1861, Goebel (9), and others.
Speaking generally, we may say that a leaf com-
mences as a small conical projection immediately below
the growing-point of the shoot (fig. 58). It continues
to grow at its apex for a short time only, its develop-
DEVELOPMENT OF LEAVES AND STIPULES 47
ment being completed by growth in a zone of cells
situated just above its base (intercalary growth). So
that, as Schleiden has pointed out, while the apex is
the youngest part of the shoot, it is the older part
of the leaf. The projection gradually widens, and
often occupies more than half the circumference, thus
affording a possible explanation of the fact that, while
the cotyledons are opposite, the leaves are in so many
cases alternate.
The rudimentary leaf consists of undifferentiated
cellular tissue, and does not at first contain any vessels.
It is no part of my present intention to deal with
this interesting subject in detail, but I will give a few
cases in illustration, taking that of ordinary foliage
leaves, for in those which are intended as bud-pro-
tectors the stages are very different.
Aucuba
On account of its simplicity, I will commence with
the common Aucuba japonica of our shrubberies. The
leaves of Aucuba are opposite, ovate, and without stip-
ules. They commence as two slight projections, each of
which broadens at the base, and finally occupies one-
half of the circumference of the stem (figs. 59, 60), so
that they are concave on the inner side and almost
cover over the growing-point. They gradually elongate
(fig. 61), and from being at first slightly curved
48
BUDS AND STIPULES
round the stem, become folded lengthways or con-
duplicate. They are clothed with long, sparse hairs,
and show a few teeth, or rather knobs, along the edge,
one terminating each of the veins, which are thicker
than in subsequent stages (fig. 63). The teeth, or
d±
~>
Figs. 59-62.
Fig. 63.
Aucuba japoxica. Highly magnified.
Fig. 59, first pair of leaves, front view ; Fig. GO, ditto, side view ; Fig. 61, second
pair ; Fig. 62, ditto, more developed ; Fig. 63, third pair.
knobs, are also much larger in proportion than in the
full-grown leaf.
Common Laurel
The subjoined figures illustrate the structure of
the bud of a Common Laurel (Cerasus Lauroc&rasus).
DEVELOPMENT OF LEAVES AND STIPULES 49
Here again the leaf commences as a small projection or
lobe immediately below the growing-point. Very soon
4< *A« (6b W
t
(\
\
Common Laurel.
Fins. 64-70, leaves and their stipules ; «, f, stipules ; x 10.
Figs. 71-79, outer scales.
two other lobes appear at the base of the first (fig. 64, s,s).
These are the stipules. They are at first much smaller
50 BUDS AND STIPULES
than the leaf. By the time, however, that the leaf-blade
has reached 3-^ th inch (fig. 67) the stipules have caught
it up. They are more oval, more pointed, and bordered
by a row of small projections. They continue to grow
(fig. 68) more rapidly than the leaf-blade, and some-
what unequally (fig. 69), the larger one becoming
rather more (fig. 70), the shorter one rather less, than
double as long as the leaf-blade. Then comes a some-
what abrupt transition, and the outer scales do not,
of course, correspond to stages in the development of
a normal leaf. A rudimentary leaf, such as that in
fig. 70, is followed by a scale of quite a different
form : broader, wrapping round the bud, and consisting
of three parts nearly but not quite equal in length,
and separated almost to the base (fig. 71) ; the two
outer pieces representing the stipules are rather
broader than the central. In the next (fig. 72) the
leaf-blade is rather longer than the stipules, and the
common stalk or leaf-base is longer in proportion.
This is still more the case in the next two (figs. 73, 74).
In the twelfth (fig. 75) the leaf-stalk is abruptly trun-
cated ; and in the following the stalk and stipules are
reduced to three small prominences. Finally, the outer
scale is much shorter and broader in proportion (fig. 79).
The Tulip Tree (Liriodendron tulipifera)
In the Tulip Tree the leaf commences as a slight
projection immediately below the growing-point, and
DEVELOPMENT OF LEAVES ANT) STIPULES 51
gradually widens into a ridge, the two ends of which
eventually meet, forming a ring.
One part raises itself above the rest and forms the
leaf-stalk ; the two side pieces become the stipules.
They grow upwards and inwards, finally forming a
hood over the growing-point. About the time when
Tulip Thee (Lirioclcndron tulqnfera).
FlG. 80. — Very young leaf and stipule, x 20. Fig. 81.— Do. do. second stage, x 20.
FlG. 82.— Do. do. rather more advanced stage, x 80.
the stipules meet the leaf-blade commences. It is at
first a very narrow, delicate, hyaline membrane. The
bud then assumes the appearance shown in fig. 80.
The next stage (fig. 81) shows the growth of the
leaf-blade, which is more developed in fig. 82. Fig. 17,
p. 14, shows how closely the young leaf fits in the
e2
52 BUDS AND STIPULES
hollow of the bud ; while the final arrangement of the
leaf in the bud is shown in figs. 17 and 18.
In the axillary buds, as a rule, the outer covering
consists of two stipules, the rest of the leaf not being
developed (fig. 83). Sometimes, however, at the base
a small projection may be seen (fig. 84), which is a
83 84 85 86
Figs. 83-86. — Tulip Tree. Outlines of different axillary buds.
rudiment of a petiole. Sometimes this is rather more
developed (fig. 85), and sometimes a rudimentary blade
also appears (fig. 86).
The reversal of the leaf in the bud, owing to the
length and early development of the petiole, is* very
unusual. In Amicia Zygomeris the leaf is bent, but
only forms a right angle with the petiole.
Rose
The leaf of the Rose (see ante, fig. 58, p. 46) is more
complicated. It commences as a small knob at the
side of, and immediately below, the growing-point.
When this knob has reached a certain length it pre-
sents two lobes (fig. 87), which arise almost simul-
taneously.1 The upper of these becomes one of the
1 According to Schacht, however, the stipule appears first.
DEVELOPMENT OF LEAVES AND STIPULES 53
upper leaflets, the lower is one of the stipules. Almost
immediately a third, and then a fourth, lobe make their
appearance. The third is the rudiment of a leaflet of
the second pair, the fourth of the third.
Thus the stipule appears almost simultaneously
with the first and upper leaflet, before any of the lower
Fig. 87.— Growing-point of Rose with Two Leaves in successive
Stages of Development. Highly magnified.
and later ones. These originate close above the
stipules. Gradually, however, the petiole elongates,
thus carrying the lower leaflets away from the stipule.
De Candolle described the stipules as being connate
54
BUDS AND STIPULES
with the petiole. This, however, is not, I think, strictly
correct. The true petiole is the leaf-stalk above the
stipules. The winged part below is really a develop-
ment of the leaf-base.
Adnate stipules, as these are called, arising from a
similar development of the leaf-base, occur in many
Fig. 88.— Section acbosr the Bud or a Kose.
A, growing-point ; L1, youngest leaf ; LJ, three folded lobes of second leaf
St'-, stipules of second leaf ; Sc'-Sc5, scales.
other cases, as, for instance, in some Lupins, Clovers,
Potentilla, &c. That winged petioles are not always
stipular is, however, shown by the case of Lathyms ;
for instance, L. silvestris.
DEVELOPMENT OF LEAVES AND STIPULES 55
The rudimentary leaves in the Rose pass gradually
into the bud-scales ; the transition is not so abrupt as
in the Aucuba or in Maples (fig. 8, p. 7).
If we examine a Rose-bud in winter, the first or
outermost scale (fig. 89) is unequally triangular, as a
rule acute, carinate, and small. The second one is very
similar, at least in the case of lateral buds. The third
scale (fig. 90) is much larger, and rounded at the
apex, or occasionally emarginate by the breaking away
of the tip, and more or less strongly carinate. The
89 90 91 92 93 94
Bud-scales of Kosa canina, x 2.
Fn:. Kf), first soak: : Fig. 90, third do. ; Fig. 91, fourth do.; Fig. 92, fifth do.;
I'm;. 93, sixth do. ; FrG. 94, ninth do.
fourth scale (fig. 91) is twice as large as the third,
broad at the apex and tridentate, the middle tooth
representing the petiole, and the more obtuse lateral
ones the stipules.
The fifth scale (fig. 92) is rather narrower, but
covers about half of the bud, and the middle tooth is
slightly the longest. The sixth scale (fig. 93) is the
longest, surmounting the bud, and folded round it so
as to cover about three-fourths of its surface ; the
three teeth are about equal in length. From this point
onwards the scales get rapidly shorter and smaller.
With this difference the seventh and eighth scales are
56
BUDS AND STIPULES
similar to the sixth; they are rolled round the bud,
covering about seven-eighths of its surface, and over-
lapping at their apex. The middle tooth at the apex
has slightly increased in length. This is even more
evident in the ninth (fig. 94) and tenth scales, both of
which are small.
Fig. 96.
Fig. 95.
kosa canina.
Fig. 95.— Stem bearing expanding lateral bud, x 2 ; one scale has fallen, revealing its
axillary bud (b) ; five scales are shown, and two of the first leaves. Sketched
March 24.
Pig. 96.— Uppermost scale, immediately preceding the first true leaf, x 2 ; l, unde-
veloped blade ; if, si, stipules.
The eleventh scale may be described as the first
normal leaf, though still rather imperfect. The leaflets
are represented by small or narrow teeth, crowded
together. The stipules are now well developed, and
much larger in proportion to the rest of the organ than
DEVELOPMENT OF LEAVES AND STIPULES 57
in previous cases. The second leaf, occurring at the
twelfth node, has a more elongated lamina, though still
rather imperfect. The stipules are well developed, and
as in the previous case, they cover about three -fourths
of the bud. Succeeding ones are very minute, and
appear to be perfect leaves. No free petiole is to be
seen at this stage of the bud in winter, the stipules
being adnate along the whole length of the midrib; so
that the lamina of the leaf is sessile.
The above description was made from an average
bud on a strong shoot. Buds on weak shoots have
fewer scales. Buds examined in January were still dor-
mant, or nearly so ; and this applies to most or all of the
British Roses. Some exotic species, such as Rosa indica,
R. multiflora, and others of that type, are almost burst-
ing into leaf at the same date, if the weather is at all
mild. The appearance of a developing bud in spring,
with one leaf nearly expanded, is given in fig. 95.
In the Rose, as we have seen, the development of
the leaflets proceeds from above downwards, the upper
leaflets being the older. This mode of growth, there-
fore, has been termed ' basipetal' (fig. 97). The same
sequence is followed by many other Rosacece, Valeriana,
Melianthus, Reseda, Grasses, Cyperacece, Lilies, Orchids,
and probably all Monocotyledons.
On the other hand, there are also species in which
the reverse takes place — i.e., in which the lowest lobes
are the oldest, and others are developed upwards, i.e.,
58 BUDS AND STIPULES
are basifugal (fig. 98), as in the Pea, Ailanthus, Maho-
nia, &c.
A similar difference in the mode of growth may be
shown to occur even when there are no leaflets. Thus,
Steinheil made a nick with a knife on a young
growing leaf of Afesembryanthemum, half way up, and
found that in the full-grown leaf it was much nearer
the apex than the base. M. deltoideum has a number
of small fleshy points, especially one at the summit, and
two at each side. These are in proportion much nearer
Fig. 97.— To Illustrate Fig. 98. — To Illustrate
Basipetal Growth. Basifugal Growth.
the base in the young than in the full-grown leaf.
Again, in Urtica biloba the notch at the apex of the leaf,
from which the species takes its name, reaches in the
young leaf to the centre, but in the full-grown leaf
only a third or a quarter of the length. In pinnate
leaves the insertions of the pinnae are, as Steinheil says,
marks written by Nature on the leaves, and when, as in
many cases, they are nearer together at the base, the
upper leaflets are the older and the lower ones younger.
Thus, a growing leaf of Asclepias syriaca may have six
DEVELOPMENT OF LEAVES AND STIPULES 59
pairs of lateral nerves in the upper half of the leaf and
eighteen in the lower. In the perfect leaf, on the
contrary, each half bears thirteen.
In some cases, however, the growth of the leaf as a
whole and that of the separate leaflets follows different
lines.
Trecul, moreover, has shown that the development
of leaves cannot in all cases be brought under these two
categories. In Gentaurea, for instance (fig. 99), the
central lobe is formed first, and
others appear successively, both up-
wards and downwards.
There has been much difference
of opinion whether any, and, if so,
what, other modes of development
exist in addition to those already _
J Fig. 99. — Young
mentioned, but from my special Leaf op Centaurea
. , r . ... scabiosa, x 14. The
point of view it is not necessary to iarger leaf embraces
go into this question. J y°unSer one at its
& ~ base.
Galium
The following figures, after Eichler, illustrate the
development of the leaf in the Ladies' Bedstraw
(Galium Mollugo). Fig. 100 gives a vertical view of the
tip of a shoot. Round the central growing-point is
a nearly circular ridge. Immediately below this is
another ridge, which shows a number of small emi-
nences— two larger, right and left, which are the rudi-
60 BUDS AND STIPULES
ments of the leaf-blades ; and four smaller, at the four
corners, which represent the rudiments of the four
leaf-like stipules, two belonging to each leaf.
Fig. 101 represents a rather more advanced stage,
in which two other knobs (one of which is already
indicated at the top of the left-hand figure) have
made their appearance, which complete the ring of
til
If
Fig. 100. Fig. 101.
Leaf Development in Galium Mollugo. Highly magnified.
eight so-called leaves. This figure is taken from a
lower node, the leaves of which will be at right angles
to those of the previous node. Hence the leaf-rudi-
ments which were to the right and left in the first
figure now stand above and below, while the last added
rudiments stand right and left. The four true stipule-
rudiments still occupy the corners.
Some leaves have what is known as an ' ocrea.'
This is a sheath which, taking its origin at the base of
the leaf, surrounds the stem above it for a greater or
less distance. Ocreas occur in the Plane, Dock
(Rumex), Polygonum, Pondweed (Potamogeton), &c.
DEVELOPMENT OF LEAVES AND STIPULES 61
The Plane (Platanus)
The leaf of the Plane originates in a ridge which
' .0'
Figs. 102, 103. — Leaf Development in Platanus occidentalis.
The upper figure shows the growth of the first leaf-ridge (o1) round the growing-
point, A. The ridge is not yet complete, being still open towards the front.
The outermost row of cells is the inner surface of the base of the protecting
lpiif-stalk.
The lower figure (transverse section) shows three leaf-ridges (o'.o'.o3) surrounding
the growing-point, A. The youngest ridge (o1) is still incomplete.
runs round the whole axis immediately below the grow-
ing-point.
62 BUDS AND STIPULES
At one place it raises itself more than elsewhere,
and develops two side processes — the two primary leaf-
lobes. These soon develop two side lobes. In the
meanwhile the conjoined stipules gradually close over
the growing-point, and finally cover it entirely. They
do not, however, coalesce in the centre, but only touch.
At a later period the edges turn outwards and assume
a leaf-like form (fig. 136).
The account given by Benjamin (10) is somewhat
different, but I believe that of Eichler, confirmed by
Mikosch, is substantially correct.
Polygonum
In Polygonum also the leaf arises as a small projec-
tion just below the growing-point, and gradually ex-
tends round it.
This ring, which originates the primordial leaf, is
higher at one place, which will develop into the leaf-blade.
The rest of the ring grows and extends across the base
of the leaf until it entirely surrounds the growing-point,
forming the ocrea, and often projects some way beyond
the growing-point. It completely covers the bud, which,
however, eventually forces its way through.
Vernation
The attitude of leaves in their very young stage is
termed by botanists f vernation.' Some lie flat, as, for
DEVELOPMENT OF LEAVES AND STIPULES 63
instance, the Mistletoe and Mesemhryanthemum. This
is usually the case with fleshy leaves. Among the most
common modes of folding are the following, which are
illustrated by the diagrams in fig. 104.
1 . Conduplicate : when folded lengthways, doubled
up on the midrib, as in the Rose, Bramble, Tulip Tree
(fig. 104, A).
X
B
Fig. 104. — Diagrams illustrating Vernation.
2. Plicate, or plaited : when folded like a fan on
the ribs, as in the Maples, Currant, and most palmate
leaves (fig. B).
3. Circinate : when coiled like a crozier, as in the
Ferns, Drosera, &c. (fig. C).
4. Revolute : when rolled backwards from the mar-
gins, as in Azalea, Rosemary, and many plants of hot,
dry places (fig. D).
5. Involute: when rolled inwards from the margins,
as in Violets, Water Lilies, &c. (fig. E).
64 BUDS AND STIPULES
6. Equitant : when the leaves are folded one over
the other, as in Grasses, Sedges, Iris, and many other
Monocotyledons (tig. F).
7. Convolute : when rolled up from one margin —
i.e. one margin within, the other without the coil, as in
the Cherry, Peach, Pea, Vetch, &c. (fig. G).
There are sometimes considerable differences be-
tween nearly allied species ; and in some cases the outer
and inner leaves of the bud assume different positions.
The conduplicate arrangement seems to follow natu-
rally from the mode of development described on p. 47.
The rudiment of the leaf, spreading more or less
round the growing-point, assumes a hollow form, and
when it rises above the central axis would thus become
folded on itself.
In pinnate leaves generally, as in those of the Rose,
each leaflet is conduplicate.
In palmate leaves the folded arrangement is that
naturally best calculated to enable them to fit into the
bud.
The involute and revolute types perhaps have refer-
ence to the later life of the leaf, as affording a certain
protection against too rapid transpiration.
The equitant type follows naturally from the mode
of growth of many Monocotyledons.
Leaves of the same form may be folded in very
different ways, and it is seldom that the same plan runs
through a whole family, at least among Dicotyledons.
DEVELOPMENT OF LEAVES AND STIPULES 65
The leaves of water-plants are as a rule flat or
rolled, not folded.
The consistence of the leaf exercises much in-
fluence, for thick, leathery, or fleshy leaves, such as
those of Mistletoe (ViscumJ, Aloe, many Crassulas,
Saxifragas, &c, naturally are as a rule flat ; some-
times rolled ; but rarely folded. Pinnate and trifoliate
leaves are generally folded.
In Monocotyledons the leaf rises as an elevation
immediately below the growing-point, gradually sur-
rounding part of the stem, and highest at the point
opposite the opening. The ridge extends until it forms
a sheath more or less completely surrounding the stem.
The leaves, of Palms and Aroids develop in a
manner very unlike that usual among Dicotyledons.
The leaf originally forms a continuous blade, which
is much folded, and subsequently divides. According
to Eichler, this is effected by a process of disorganisa-
tion at the edge of the fold. A similar process occurs
in the segmentation of the originally entire th alius of
species of Lammaria, a common genus of brown sea-
weed. Naumann (11), on the contrary, maintains that
the cells along the line of the fold detach themselves and
diverge from one another. I believe, however, that
Eichler's view is correct.
66 BUDS AND STIPULES
CHAPTER IV
ON THE PROTECTION OF BUDS
Young leaves are extremely delicate. They require
protection from too great heat, cold, dryness, moisture,
and light, as well as against the attacks of animals.
For this purpose they are often provided with a
covering of more or less woolly hair, which generally
drops off when it has served its purpose.
In other cases the outer envelopes of the bud are
specially modified for the purpose.
As Grew (12) quaintly says : ' According to the Form
and Foulding of every Leaf or Germen, is its Protection
order'd ; about six ways whereof may be observed ;
sc. by Leaves, Surfoyls, Interfoyls, Stalks, Hoods, and
Mantlings. To add to what we have above given, one
or two Instances. Every Bud, besides its proper
Leaves, is covered with divers Leafy Pannicles, or
Surfoyls ; which, what the Leaves are to one another,
are that to them all. For not opening except gradually,
they admit not the Weather, Wet, Sun or Air, to
approach the Leaves, except by degrees respondent,
and as they are gradually inur'd to bear them. Some-
times, besides Surfoyls, there are also many Interfoyls
ON THE PROTECTION OF BUDS G7
set betwixt the Leaves, from the Circumference to the
Center of the Bud ; as in the Hasel.'
Here he uses the term * Surfoyls ' for the outer
scales, whatever their true character may be. His
• Interfoyls ' are stipules.
Besides the protection afforded by actual coverings,
the opening buds in many cases guard themselves, to
some extent, at any rate, by assuming either an erect
position, as in the Whitebeam (Pyrus Aria) (PL II.
fig. 5), Acer lAatanoides (PL II. figs. 2-4), and, I be-
lieve, most shrubs with opposite leaves ; or a drooping
attitude, as in the Lime (Tilia) (PL I. figs. 1-3),
Beech (Fagus) (PL IV.), Hazel Nut (Corylus), Elm
(Ulmus) (PL III.), &c. The great leaves of Palms are
at first vertical.
One advantage thus gained is that the radiation
is much less than it would be if the leaves were to
assume at once their permanent horizontal position.
Darwin has shown that this position really does tend
to check the effect of radiation. Our experiments, he
says, ' show that leaves compelled to remain horizontal
at night suffered much more injury from frost than
those which were allowed to assume their normal vertical
position/ l
' We exposed on two occasions during the summer
to a clear sky several pinned-open leaflets of Trifolium
pratente, which naturally rise at night, and of Oxalis
1 Movements of Plants, p. 280.
f2
68 BUDS AND STIPULES
purpurea, which naturally sink at night (the plants
growing out of doors), and looked at them early on
several successive mornings, after they had assumed
their diurnal positions. The difference in the amount
of dew on the pinned-open leaflets and on those
which had gone to sleep was generally conspicuous,
the latter being sometimes absolutely dry, whilst the
leaflets which had been horizontal were coated with
large beads of dew. This shows how much cooler the
leaflets fully exposed to the zenith must have become
than those which stood almost vertically, either upwards
or downwards, during the night.
' From the several cases above given there can be no
doubt that the position of the leaves at night affects
their temperature through radiation to such a degree
that, when exposed to a clear sky during a frost, it is a
question of life and death.' '
It is probable, however, that in some cases, at any
rate, this position is assumed as a protection against
too intense light.
The principal modes by which buds are protected
are :
1. By the expanded base of the preceding leaf.
2. By scales which represent modified outer leaves,
as in Willows, Ash.
3. By the outer leaf-stalks, as in Maples, Ash.
4. By stipules, as in the Beech, Oak.
1 hoc. cit. p. 293.
ON TIIK PROTECTION OF BUDS 69
5. By the two connate stipules of a leaf, as in the
Elm, Spanish Chestnut.
G. By two connate stipules belongiug to different
leaves, as in the Hop.
7. By spines.
S. By furry hair.
9. By gum, resin, or mucus.
In considering the protection of buds in their
youngest stages we must distinguish between two
different cases : the first, where the young bud as a
whole is protected by older organs ; and the second,
when the future leaves are protected by the outer bud-
scales.
The cases in which the young bud is protected by
older organs may be divided into four principal cate-
gories :
1. Those in which the protection is mainly afforded
by leaf-blades.
2. Those in which the protection is mainly afforded
by the petiole or by the leaf-base.
3. Those in which the protection is mainly afforded
by stipules.
I . Those in which the protection is mainly afforded
by hairs.
Protection by Leaves
In hot countries, where the young bud principally
requires protection from the scorching rays of the sun,
this is often effected by their simply lying under the
70
BUDS AND STIPULES
shelter of older leaves. A good example is afforded
by TJvaria purpurea, which has been described and
figured by Mr. Potter (1 . 349). ' A front and also a back
view of a shoot of this plant are shown in figs. 105
Fig. 105.
Fig. 106.
Shoot of Uvaria purpurea.
Fig. 105, front view. Fig. 106, back view.
and 106, where fig. 105 is the front view and fig. 106 the
back view of a similar shoot. The shoots themselves are
in this plant slightly inclined to the vertical, so that by
this means the younger leaves are protected from the sun's
ON THE PROTECTION OF BUDS
71
heat. On examining the front view (fig. 105), we see that
the three leaves a, b, c, are so arranged that they com-
pletely cover over the growing-point and its younger
leaves, so that these latter are- completely shielded ;
while the back view (fig. 106) shows how the younger
Fig. 107. Fig. 108.
Shoot of St. John's Wort (Hypericum), showing protection
of the young pair of leaves (b).
I'm;. 107.— Side view. FlG. 108.— Front view.
internodes, with their smaller leaves, are hidden behind
the large leaves. The young leaves as they attain to
their mature size assume the same relative positions,
and so protect other young leaves, and so on.' I have
already referred (ante, pp. 4, 5) to the cases of Begonia
and Rhubarb.
72
BUDS AND STIPULES
In other cases the leaves form successively a more
or less complete covering for those that follow, as, for
instance, in the St. John's Wort (Hypericum) (figs.
107, 108).
In the Common Barberry (Berberis vulgaris) (fig.
109) the primary leaves are changed into spines.
The bud, however, in the axils of these spinose leaves
A develops into a short axis with
foliage leaves. This is why
the leaves in this species are
collected in tufts.
In Azima tetracantha (a
member of the Salvadoracece,
a small tropical family of Di-
cotyledons) the axillary buds
are rather remarkable. What
3ak_ appear to be two spines situ-
berry (Berberis vulgaris), ated in the axil of the leaf
showing three spines, Sp,
representing the leaf. Nat. are really the first pair of
A, s^m'; l. L, leaves on a lateral leaVeS °f the axillary shoot,
shoot arising in the axil of the t_ it •_ „,„1_ -*-,-,«#»« ±1,^,-, „~~
spiniform eaf, and themselves In their early stages they are
red uced to short, subulate spines ; , , ,. , .,
i/, L',more perfect leaves on the erect, closely applied, and very
same lateral shoot.
short, but when fully developed
they become hard, spiny, and diverging. Their foliar
nature is further indicated by the fact that a slender
groove runs along the opposing faces from apex to
base, where there is a deeper cavity, as if a sheath
were attempted. They are also articulated with the
ON TIM: PROTECTION OF BUDS 73
stem. The second and third pairs of leaves on the
axillary shoot (when the latter develops) are reduced
to scales, which decussate with the spines. True leaves
follow the scales.
Protection by the Leaf-base or the Leaf-stalk
The axillary buds are thus protected in most
Composites, Umbellifers, in the whole family of the
Garyophyllaceon (Pink family), except Spergula and
Spergidaria, in the Gentians,
and many other families.
In all these species the base
of the petiole is more or less
dilated, so as the more effec- C~ ~~\
tually to protect the bud.
Fig. 110. — Section across
Fig. 110 represents a sec- the Stem of a Walnut.
. • , i o L, petiole : B, bud ; Glandular Secketing Hairb in-
Lilac (Syringa vulgaris).
In fig. IS9, b, the .--talk lias not been formed.
branch, and one fork may remain a simple pointed hair,
while another develops a gland.
The glandular processes are sometimes highly deve-
loped; as, for instance, in the Rose and the Violet,
where they are large and oval, one being formed at the
tip of each tooth of the leaf.
In the Docks (Bamex), Polygonum, and Rhubarb
(Rheum) the buds secrete a copious mucus, which in
some of the larger species can even be squeezed out
ON THE PROTECTION OF BUDS
95
in a drop. It is formed by papillary outgrowths of the
epidermis.
The buds of Chilocarpus look as if they were covered
by red sealing-wax (16).
*)
•x P
Figs. 140, 141. — Development of Hairs in Plane
(Platanus acerifolia).
An epidermal cell divides into two unequal parts by an oblique wall. The upper grows
out into a 2-4-celled hair, the apical cell of which becomes a spherical gland-cell ;
a lateral cell grows oat obliquely into a long, pointed, hair-like structure.
The lower figure Bhowa tin- development, the upper the perfect form of the hairs.
The case of Tabemannontana (1, 35i) is especially
interesting. The buds of this plant are covered with a
96 BUDS AND STIPULES
gum which does not completely harden, but remains in
a semi-fluid condition ; and as the leaves previously
covered up grow and expand, the gum remains attached
to their edges, and stretches as a thin film between
them. Thus the next youngest leaves are for a certain
time enclosed in a small four-sided chamber, two oppo-
side sides of which are formed by two leaves, and the
other two opposite sides by a thin film of gum. The
gum is eventually ruptured and the same process is
repeated.
Glands are present in the axils of the leaves in the
great majority of Crucifers (Norman says in nine-tenths),
in most Lythrariece, and in many others.
The connection of these glands with the protection
of the young and highly delicate leaf is further shown
by their very early development. In fact, in some spe-
cies there is a stage in which the glands are actually
larger than the rudiment of the leaf itself. They are,
however, often very transitory.
97
CHAPTER V
ON THE STRUCTURE OF BUDS
Having thus glanced at the various ways in which buds
are protected by other and older structures, let us now
see how they behave when they are, so to say, thrown
on their own resources. In doing so I will, as far as
possible, take in illustration our familiar forest trees and
other common plants.
It is in some respects difficult to draw a hard-and-
fast line between the buds now to be considered and
those described in the last chapter.
In the Whitebeam (Pyrus Aria) (fig. 125, p. 82), for
instance, the pedestal of the last leaf of the previous
year is persistent, and, no doubt, of some use to the very
young bud ; but I class it here because in the main the
shelter is due to the outer, modified stipules belonging
to the bud itself.
It is remarkable how many devices Nature has
adopted, and how much even nearly allied groups, such,
for instance, as the Willows and Poplars, differ from one
another.
It is, indeed, a very general, though not invariable,
rule that the outer envelopes of winter-buds are formed
H
98
BUDS AND STIPULES
of brown, more or less leathery scales ; but as we shall
see, these scales represent very different organs.
If we examine the bud of an Alder (Alnus glutinosa)
(figs. 142, 143, 144) in winter, we shall find that it is
s \
Fig. 142. Fig. 143.
Bud of Alder (Alnus glutinosa).
Fig. 142.— Portion of shoot, showing two lateral buds in winter ; Sc, scar of fallen
stipule, leaving L, the corresponding leaf, exposed ; St, the stipule of the next
leaf ; the upper bud shows only one stipule, St, but none have fallen in this
instance, which is the more common case. Nat. size.
Fm. 143. — Transverse section of bud in winter, x6 ; A, a, first or outermost pair of
stipules, belonging to the leaf immediately beneath them ; B, B, second pair of
stipules with their leaf ; < , c, third pair ; the fourth leaf, D, D, and stipules
occupy the centre ; Ax, axis.
protected by three, or sometimes four, purplish brown,
leathery scales. The lateral buds sit on gradually elon-
ON THE STRUCTURE OF BUDS
99
gating pedestals. If there are three scales, these are
stipules. When four are present, one will be found to
have at the end a few finger-like processes (fig. 142, L),
the rudiment of a leaf-blade. At the base will be found
the more or less evident scars left by the two stipules.
as. I.
I s
o.sb
o St. I
148
ISt.
147
Alnus glutinosa, x 3.
Fig. 144.— Portion of shoot bearing a lateral bud ; o.s., outer scale ; s.s., second scale —
that is, the outer one of a pair of stipules.
Fin. 145. — Outer scale of winter-bud.
Fkj. 1 10. — o.s., outer, and i.s., inner stipule of the first distinct pair ; I, their leaf,
flattened out like the stipules.
I'ic. 147. — o.st., outer, and Lst., inner stipule of the second distinct pair ; /, their leaf.
Fie. L48.-o.Jt, outer, and i.xt., inner stipule of the third distinct pair ; I, their leaf.
In this case, therefore, the last leaf of autumn is small,
and sooner or later falls off; but, in connection with the
stipules of the next leaf, it often assists in protecting
the bud through the winter. It often, however, be-
comes detached, and in such buds as shown in the trans-
it
100
BUDS AND STIPULES
verse section (fig. 143) the young leaf-blades are pro-
tected by three stipules, two belonging to the outer leaf,
the third to that next following.
Here, therefore, though the main protection is
afforded by stipules, the leaf-stalk and leaf-blade of an
older leaf sometimes take a part in it.
Fig. 149.
Fig. 150.
Fig. 151.
Magnolia Yulan, x 2.
Fig. 149.— Shows uppermost leaf with its stipules protecting the terminal bud
in autumn ; b, bud in tfce axil of the next lower leaf which has fallen.
Fig. 150 . — Second stage, shows aborted leaf, a, the stipules of which protect
the winter-bud.
Fig. 151. — Side view of same.
The second pair of stipules (fig. 147) of the more
typical lateral buds are free, unequal, imbricate, and
completely cover their own leaf and two out of the three
sides of the more or less trigonous bud. The outer stipule
ON THE STRUCTURE OF BUDS 101
of this second pair is ovate, more or less exposed along
the middle and at the apex, which is curved, the exposed
portions being more coriaceous than the rest. The inner
of the two is half-ovate, pale green, and membranous.
Both are traversed longitudinally by slender parallel
Fig. 152. Fig. 153.
Terminal Bud of Magnolia Umbrella, x 1£.
Fig. 152. — Uppermost leaf still present.
Pl&. 153.— Uppermost leaf has fallen, leaving only a pedestal, p ; its stipules
remain to protect the winter-bud.
nerves. The leaf in connection with the second pair is
lanceolate-oblong, acute, serrate, glandular, and plicate
along the course of the ascending nerves. It is more
or less folded over the younger members of the bud. All
the leaves and stipules are glued together by a viscid,
resinous, fragrant gum, secreted by glands.
The third pair of stipules (fig. 148) are slightlvun-
102 BUDS AND STIPULES
equal, narrowly ovate or lanceolate, membranous, and
more faintly nerved than the previous pair. The outer
stipule envelops about two-thirds of the bud, including
its fellow-stipule and the leaf. The latter is ovate-
elliptic and folded over the younger members of the
bud as a rule. The fourth pair of stipules and their
leaf (fig. 148) are sometimes very similar to the preced-
ing set, sometimes much smaller. This difference is
apparently due to the relative vigour of the axis
bearing them.
A somewhat similar case is afforded by certain
species of Magnolia. In Magnolia Yulan the stipules of
the uppermost leaf protect the young bud in autumn (fig.
149), but when it drops the stipules fall with it. This
leaves a small undeveloped leaf-blade (fig. 150, a), which
soon perishes. The stipules belonging to it, however,
remain, and form a silky case, which protects the bud.
The leaf-blade corresponding to a, therefore, is
useless and wasted.
Another species (Magnolia Umbrella) (figs. 152, 153)
avoids this waste of power and material. When the last
leaf of the y ear dies and drops off, the stipules belonging
to it remain and protect the bud (fig. 153). Under these
circumstances the leaf corresponding to a, which in
Magnolia Yulan perishes uselessly, in Magnolia Umbrella
is still retained, and develops into the first leaf of the
following year. In M. Soulangiana, a garden hybrid,
there is a similar arrangement.
ON THE STRUCTURE OF BUDS
103
Protection by thb Leaf-base
rose
The bud of the Rose in December (figs. 154-9) consists
of a number of scales with three more or less well-marked
154
Scales of Rose-bud.
In.. 154. first scale : Fi<;. 155, third do. ; Fig. 156, fourth do. j Fig. 157, fifth do. ;
PlO. 158, sixth do. ; FlO. 151). ninth do.
projections at the apex. In this case the scale itself
represents the leaf-base, while the stipules and upper
Fig. 160. — Expanding Bud of Rose.
Stein bearing expanding lateral bud, x2 ; one scale has fallen, revealing its axillary
bud (b) ; five scales are shown, and two of the first leaves. Sketched March 24.
part of the leaf are indicated by the three points. The
outermost scale is the shortest, and they gradually
104 BUDS AND STIPULES
increase in length. After about ten of such scales the
little leaf-blade becomes much larger, and the leaf-base
smaller, in proportion (see fig. 160).
PORTUGAL laurel (Prunus lusUanica)
The bud-scales of the Portugal Laurel are also leaf-
bases. They are serially continuous with the leaves.
The first scale covers less than half the bud and
overlaps the second slightly at the base. It presents
three points at the apex, or rather two points with a
blunt process between them. These are the rudiments
of the petiole and stipules. The second scale is longer,
but otherwise not materially different. The third scale
attains the full length of the bud, the petiole being
more acuminate than in the previous scale, and longer
than its stipules. The fourth scale is precisely similar,
and covers more than half of the bud. All the stipules
are ciliate and serrulate.
The fifth scale is shorter, and much more rounded
at the base. It covers three-quarters of the bud or
more. The sixth and seventh scales are smaller and
shorter than the previous ones, and cover the bud, with
the exception of a small slit at the base, where the edges
of the stipules do not come in contact.
At the eighth node in the terminal bud examined the
first true leaf occurred. It was small, subulate, slightly
conduplicate, but colourless, and much shorter and
narrower than its green and ciliate-serrulate stipules.
ON THE STRUCTURE OF BUDS 105
The ninth and tenth nodes bear leaves somewhat better
developed, but their stipules are smaller and narrower.
The fourth leaf, at the eleventh node of the bud, is
conduplicate, and as long and about as wide as its
stipules, without being unfolded. Succeeding leaves
and stipules are very much smaller in the bud at this
stage, but otherwise similar to the fourth.
It will be noted that the stipules become almost
separate from their leaf from the first one onwards, even
in the bud stage. The stipules are deciduous, falling
before the end of the summer.
maple (Acer)
In species which have no stipules there is nothing
to distinguish the base of the leaf from the petiole.
Thus, if we look at the winter-bud of a Sycamore, a
Maple (figs. 161, 162), or a Horse Chestnut, we find it
covered by a number of brown, leathery scales, which are,
like the leaves, opposite and decussate, so that one might
at first sight be disposed to regard them as a simple form
of leaf. On looking more closely, however, we shall
soon find one which shows a scar or three small teeth
at the summit. When the plant begins to grow in
spring some of the scales, especially on certain trees,
enlarge somewhat, and show small but often well-
developed leaf-blades at their tip. In the Norway Maple
(PL II. figs. 2-4) these scales enlarge and assume a
106
BUDS AND STIPULES
beautiful red colour, so that the growing bud looks
almost like an opening flower.
These bud- scales, therefore, are evidently the bases
of leaf-stalks.
If, without waiting for the spring, we open a bud
Fig. 161. Pio. 162.
Buds of Maple.
In.. 1 til. —Leaf- bud. Fig. 162.— Flower-bud.
in summer, say in July, we shall find five or six pairs
of scales, each pair at right angles with the pre-
ceding, and then a beautiful little crown of tender green
leaves. Fig. 161 shows such a bud, drawn in December,
after the removal of one of the last pair of scales. The
remaining scale is shown forming a large hood over the
little leaves, which at Christmas only occupy about half
the space in the bud.
ON THE STRUCTURE OF BUDS
107
Other buds (fig. 162) contain flowers. Both are
lovely, and I do not know which is the more exquisite.
ash (Fraximis)
The buds of the Ash (Fraxinus excelsior) (figs. 1 63-5)
are olive-green, so dark as to be almost black. Tennyson,
in the ' Gardener's Daughter,' describes Juliet's hair as
More black than ash-buds in the front of March.
The stems are much paler. The lateral buds are
almost completely covered by the two outer scales. The
Fig. 163. Fig. 164.
Ash Buds. Nat. size.
Fig. 166.
In fi.Lr. 164 and fig. 165 successive pairs of scales have been removed from the
terminal bud.
scales of the terminal bud are often more or less bent.
The scales are leaf-stalks, and generally show more or less
rudimentary leaflets at the tip. The outer scales are
108 BUDS AND STIPULES
thick, and rather furry on the inner side. The second
pair are furry on the outer side, and especially on the
edges. The third pair still more so.
The outer scales are not dead, like those of so many
trees, but increase more or less in size. The dark
colour is due to a layer of black, more or less angular
bodies, which are flattened hairs, containing a dark
resinous secretion, and do not increase in size or number.
As the scale grows they are, therefore, carried further
and further apart, and occupying a smaller relative
portion of the surface, the general colour becomes lighter
and greener.
HORSE CHESTNUT (JSsCulus)
The bud of the Horse Chestnut (JEsculus Hippocas-
tanum) is protected by eight or ten scales. The
outer ones are dark brown and short ; they are serially
continuous with the leaves of the preceding year.
Those following become gradually longer and paler —
often pinkish towards the end. The inner ones have a
delicate fringe along their edges. The outside of the
bud is very sticky. The scales are followed by normal
leaves. Each segment of the leaf is conduplicate, and
the midribs of the first, as well as the petiole and the
internodes, are further protected by a thick felt, which
is sometimes of a rich orange colour. This is less
developed on the inner leaves, where it would not be so
much wanted.
ON THE STRUCTURE OF BUDS
109
Protection by Leaf-blade
lilac (Syringa)
The bud of a Lilac (Syringa vulgaris) at first
sight closely resembles that of a Maple or Horse
Figs. 166-172. — Lilac, showing separated Bud-scales. Enlarged.
Chestnut, but the real structure is quite different.
Each scale here represents a leaf-blade. The first
pair (fig. 166) are short and broad; the second
(fig.. 167) are somewhat longer and pointed ; the third
110 BUDS AND STIPULES
(tig. 168) are longer than broad; the fourth (fig. 169)
still longer, and rather narrowed at the base ; the fifth
(fig. 170) begin to assume the form of the leaf, and
have a distinct, though very short, base ; the sixth and
seventh (figs. 171, 172) approximate still more to the
final form of the "leaf.
In the Holly also (Ilex Aquifoliwri) the bud-scales
are leaf-blades.
THE WILLOW (SaUx)
The winter-buds of the Goat Willow (Salix Caj>r<<()
are ovate, obtuse, tumid, relatively short, and more
or less downy. The terminal bud dies, so that
growth is renewed by the lateral ones. The bud
is covered by a cap or scale in one piece, which
shows no line of cohesion on either the anterior (fig.
173) or posterior face (fig. 171). Laterally, however,
there are two strong ribs or keels, one on each edge.
When growth recommences in spring the scale splits
regularly from apex to base on the posterior face, and
from the apex downwards, for one-third to one-half its
length, on the anterior face (fig. 175). If the scale
splits further, it does so irregularly. The whole
scale, flattened out at fig. 176, shows the extent of
the natural splitting, and also the two ribs or keels.
This method of splitting and the two ribs indicate
that the scale of the winter-bud is composed of two
leaves, inserted right and left on the axis and cohering
OX THE STRUCTURE OF BUDS
111
by their anterior and posterior edges. The first leaf-
Made (fig. 177) is roundly ovate, obtuse, densely silky
on the back and edges, and thinly hairy on the inner
face. The second and third leaf-blades are oval-oblong,
obtuse, and narrower. The fourth is oblong and more
narrowed to the base. The fifth is lanceolate ; and the
sixth and seventh are very similar. The eighth leaf-
Salix Caprea.
Fig. 173.— Portion of shoot with a lateral bud ; $, scar of fallen leaf ; s.st., scar of
fallen stipule.
Fig. 174. — Posterior view of the same bud.
Fig. 175.— Anterior view of another bud bursting, showing the silky leaves, 1,1 ; w.s.,
winter-scale.
Fig. 176.— Another view of the same scale removed and spread out, showing two
midribs, m, m ; a.e., anterior edges, slit naturally ; p.r., posterior edges, slit to
the base naturally on the bursting of the bud.
Fig. 177.— The first leaf from the bud.
blade is more decidedly narrowed to the .base, and
when in situ is more completely rolled round the bud
than the previous ones, almost entirely covering it.
It will be seen that there is little difference between
the lengths ot the first eight leaf-blades. The ninth,
tenth, and eleventh leaves are very similar to the
112
BUDS AND STIPULES
eighth, but much shorter and smaller. The stipules
are large, particularly on the leafy shoots ; but they
develop after the leaves are expanded, or during that
process. Some forms are exstipulate.
The winter-buds of the White Willow (Salix alba)
are all axillary ; the terminal one, as well as the tip of
every shoot, dies. The buds are oblong, obtuse or sub-
acute, compressed antero-posteriorly, but tumid on the
180 181 182 183 184 185
Salix alba.
1 n:. 178. — Anterior aspect of winter-bud covered with one scale.
Fig. 179.— Posterior aspect of the same, showing the median thickened suture, *.
Fig. 180. — Scales of winter-buds bursting along the suture on the posterior aspect,
showing the mass of leaves, /. bent at the apex.
Fig. 181.— First true leaf, immediately inside the winter-scale.
Fig. 182.— Second \ent Fig. 183.— Fifth leaf. Fig. 184.— Eighth leaf.
Fig. 185.— Tenth leaf.
anterior face (fig. 178), thickened at the edges, and have
a thickened suture (fig. 179) along the middle of the
posterior aspect. The cap-like scale seems to consist
of two leaves united ; its thickened edges and the
strong, slightly branched nerve, easily seen on the
inner face of these thickened edges, tend to support
this view ; but no suture is discernible on the ante-
rior face. When growth recommences in spring,
the scale bursts along the suture on the posterior
face (fig. 180).
ON THE STRUCTURE OF BUDS 113
When the tip of the scale dies in winter, it breaks
off during the bursting of the bud; and when the
whole of it dies, the growing leaves rupture it at its
insertion on the stem.
The first normal leaf-blade (fig. 181) is ovate, flat-
tened on the posterior face against the axis, incurved
at the sides, covering two-thirds of the bud. Both
the dorsal and inner faces are silky ; the edges are
ciliate.
The second leaf-blade (fig. 182) is very similar.
The third is smaller, and covers about three-quarters
of the bud, but otherwise is similar. The fourth is
smaller, but covers about seven-eighths of the bud.
The fifth (fig. 183) is lanceolate and very much
smaller, but otherwise similar to previous ones. The
sixth leaf covers the bud, with the exception of a small
slit at the base ; but the seventh overlaps at its edges,
completely enclosing the bud. The eighth leaf (fig. 1 84)
is very small and membranous. The ninth leaf is
membranous and almost glabrous; while the tenth
(fig. 185) is lanceolate, acuminate, subtransparent,
glabrous, and minute. All these smaller leaves are
completely convolute, and they gradually open at the
edges as the younger members of the bud become bulky.
The stipules are minute or undeveloped in the
winter-buds. The convolute vernation of the leaves,
and their silky, densely ciliate character amply protect
the younger members. The bursting of the winter-
I
114 BUDS AM) STIPULES
scale along the posterior face allows it to prolong its
period of protection.
I have been in some doubt with respect to the
nature of the scale covering the winter-buds, but have
come to the conclusion that this scale consists of two
modified leaves, connate by their margins along the
median line of the posterior and anterior aspect of the
bud respectively. The following reasons seem to justify
this view :
1. The scale in all the eleven species examined
burst along the posterior face, generally to the base.
Salixpijrifolia and S. reticulata are exceptions, inasmuch
as they generally split at first a little more than halfway
down. The swelling of the axis completes this operation
later on.
2. There is sometimes a ridge on the posterior face
corresponding to the line of union, as in S. alba and
S. cinerea. In S. cordata there is a wide shallow
groove at the same place.
3. The anterior face during the expansion of the
buds in spring becomes emarginate, bidentate, or more
or less deeply bifid at the upper end. 8. alba and
S. lucida are exceptions, inasmuch as the anterior face
remains entire. I have observed no ridge, indicating
union, on the anterior face ; but as this is generally
absent or inconspicuous on the posterior face, it does
not much invalidate the presumed cohesion of the
anterior edges of the leaves.
ON THE STRUCTURE OF BUDS 115
4. Another strong reason for regarding the outer
sheath as representing a pair of leaves is that it
is more or less carinate on the edges, right and left
— that is, laterally. The inner face shows a number
of longitudinal, parallel nerves, the two strongest of
which occupy the position of the carina or keel, and
correspond to the midribs of the two leaves. The mid-
ribs being right and left of the bud, agree with the
insertion of the first two leaves of axillary buds, those
leaves being generally at right angles to the leaf on the
main axis.
A curious case occurs in Salix cordata, S. lucida,
and 8. lanata. The inner membranous face of the
scale separates more or less completely from the coria-
ceous outer one, and resembles a second scale. It is,
however, exactly opposite to the outer layer of the scale
(not alternate), and is divided in the same way as the
outer layer.
Perhaps, however, the strongest reason for regard-
ing the outer sheath as composed of a pair of leaf-
blades is that we often find a pair of buds at the base.
Lindley l quotes this as showing that stipules occasionally
develop buds at their base. It seems more reasonable
to regard the fact as evidence that they represent
leaves, and not merely stipules.
It is remarkable that while in the Poplars (Pojmkts)
the buds are protected by the stipules, in Salix the
1 Introd. to Botany, p. 99.
i *2
116 Buds and stipules
stipules are minute in the bud, or even absent, and this
function is performed mainly by the leaves.
The stipules, however, though always very small in
bud, and in some species (S. retusa, Graham/i, Caprea,
repens, &c.) permanently so, in others become larger,
and in some (S. dasyclados, myricoides, &c.) attain a
considerable size. Their chief function appears to be
to protect the axillary buds, which are also sheltered by
the dilated and concave bases of the petioles. That the
winter-buds of the Willow should be protected by modi-
fied leaves is the more remarkable since some species at
least subsequently develop large stipules.
Ohlert(17) mentions the Willow among the cases in
which there is no terminal bud. At any rate, it appears
rarely, if ever, to maintain itself permanently. But,
although as a rule it soon perishes, it is formed on the
same plan as the lateral buds.
VIBURNUM (THE GUELDER ROSE)
The winter-buds of the Guelder Kose (Viburnum
Opulus), both terminal and lateral (PL II. fig. 1), are
oblong-oval, varying considerably in size, according to
their situation on the shoots and the strength of the
latter. Each bud is covered by two pairs of scales,
which are modified petioles bearing just a trace of an
undeveloped lamina at the apex.
The outer pair of scales are the most modified and
cohere by their edges ; they are inserted right and left
ON THE STRUCTURE OF BUDS 117
of the axis, and likewise of the leaf in whose axil they
occur. They are brownish red, glabrous, shining, and
for a time increase in size with the swelling of the buds
in spring. Finally, they burst antero-posteriorly along
the line of union for a quarter to three-quarters of their
length, the greatest amount of fission occurring, as a
rule, along the posterior face, allowing the developing
axis with its leaves to make its exit at the apex. Each
of these scales is keeled, the keel corresponding to the
midrib. Three or five veins may be seen on the inner
face, corresponding to the principal vascular bundles
running through the petiole into the lobes of the
lamina. Three of them generally terminate in gland-
like tips.
The second pair of scales are more membranous,
pale green, five-nerved, reticulate, cohering in a tube,
which bursts from the apex downwards for one-third
to one-half its length, or more, when growth is re-
sumed in spring. They double their length during and
after the expansion of the buds, and are, therefore,
intermediate in character between the most modified
pair of scales and the true leaves. The three principal
veins terminate in gland-like teeth, thus, possibly,
indicating the presence of the lamina in an undeveloped
state. When fully developed they are seen to be
spathulate by a dilatation of the upper half.
If the terminal bud is examined, it will be seen that
the scales are opposite decussate, and serially continuous
118
BUDS AND STIPULES
with the uppermost pair of leaves that fell in the
previous autumn. The young leaves in spring are
serially continuous with both the two pairs of scales
Fig. 186.— Viburnum
Lantana, x 2.
Fig. 187. — Part of Leaf of V. Lantaxa,
x 75, showing stellate hairs.
and the leaves of the previous season. Unless the
terminal bud ends in an inflorescence, the shoots of
successive years are interrupted only by two pairs of
scales. Strong shoots do, as a rule, terminate in an
ON THE STRUCTURE OF BUDS 119
inflorescence, and the apex dies, so that growth is
resumed by the lateral buds.
In the flowering buds the second pair of scales are
larger, vase- shaped, and also more deeply divided, es-
pecially on one side. Those which bear leaves only are
flattened at right angles to the stem.
In Viburnum Lantana (Wayfaring Tree) (figs. 186 and
187 ), on the contrary, the leaves are all normal. The outer
ones protect the inner ; but they all develop, and suffer
very little from the cold. They are protected by a thick
coat of stellate hairs, which cross and intercross, thus
forming a sort of grey felt. As the young leaves
increase in size these hairs do not appear to increase in
number, and they are, consequently, carried further
from one another. Fig. 187 is taken from such a bud
which had attained a length of rather more than an
inch.
Protection by Leaf-stalk
In the Elder (Sambucus nigra) the scales protecting
the bud are petioles. Externally are a pair of very
small brown scales ; then a larger pair at right angles ;
then a pair much more elongated, greenish, and with
more or less developed leaves. In this respect they
differ very much ; sometimes there are three small
points at the summit, sometimes a well-formed leaf; and
every gradation between the two occurs. The two
opposite leaves often differ considerably, and when one
120
BUDS AND STIPULES
of the two has its back to the main stem it is often
much smaller than the outer one.
Protection by Stipules
In by far the larger number of cases stipules protect
Fig. 188. — Shoot of Leea coccinea.
P, petiole of leaf, the lamiua being cut off ; S, stipule ; L, young leaf emerging from
stipules.
the younger leaves only, but in some species they develop
early, and cover their own leaf-blades.
This is the case, for instance, in the Pea (fig. 26, p. 23)
and the Hop (Humulus Lupulus) (figs. 47, 48, p. 34).
In the Vine, again, the stipules are large, and appear
ON THE STRUCTURE OF BUDS
121
some time before the leaves, covering the whole bud
(figs. 127, 128, p. 84). They fall early.
Fig. 189.— Virginian Creeper.
8t, stipule ; /, tendril.
In Leea (L. coccinea), another member ot the Vine
family, the same thing occurs ; they are also (fig. 188^)
large, and enclose the whole bud, but they are persistent.
122
BUDS AND STIPULES
In the allied genera, Cissus, and Ampelopsis (Vir-
ginian Creeper) (fig. 189), the stipules also cover their
own leaf-blades.
In Buchlandia populnea(fig. 190), a Himalayan plant
At
Fig. 190.— Shoot of Bucklandia populnea.
S, S, stipules ; P, petiole.
which belongs to the Hamamelidece (the Witch Hazel
family), the stipules are large, oval, unequal-sided, and
cohere at the edges, thus forming an almond-shaped box,
within which the leaf is developed. The petiole elon-
ON THE STRUCTURE OF BUDS 123
gates greatly, and becomes twice bent, as shown in
the figure, so that the leaf remains erect. This arrange-
ment is, so far as I know, unique.
In the Passion Flower (Passiflora racemosa) the
stipules are large, foliaceous, and developed far in
advance of their own leaves, so that each pair enclose
their own leaf, the simple tendril in its axil, and the
younger portion of the bud. Proceeding from the out-
side inwards, the stipules change considerably, being
first ovate, gradually becoming smaller, then lanceolate,
and finally subulate. In some other species of Passi-
flora the stipules more or less completely protect the
bud, and the petioles are terete, and are provided with
glands.
In by far the greater number of cases, however,
stipules protect the younger leaves only.
In the Willows, as we have already seen, the sti-
pules develop late, and the bud is protected by a pair
of modified leaves. In the allied genus, Populus (the
Poplar), on the contrary, the stipules develop early, and
to them the protection of the bud is entrusted.
In the Black Poplar (Populus nigra) the terminal
bud (fig. 191) is conical and somewhat angular.
The first and second pairs of scales (fig. 192), form-
ing part of the terminal bud, are stipules belonging
to leaves that developed during the previous summer
and fell in autumn. They only cover, however, a
part of the bud. They are the hardest of the
st~
193
i
198
195
POPULUS NIGRA, VAR. PYRAMIDALIS, X 2. WlNTER-RUDS.
Fig. 191. — Terminal bud showing one pair of persistent stipules, st, st, belonging to
a leaf of a previous season.
Fig. 192. — Terminal bud showing one from each of two pairs of persistent stipules,
st', st".
Fig. 193.— Axillary bud showing only one of the outer pair of stipules, si.
Fig. 194.— I, third leaf in the bud, often dying in winter ; st, si, its stipules shown
separately above.
Fig. 195.— I. fifth leaf in the bud ; st,st, its stipules.
Fig. 196. — The same shown separately.
Fig. 197.— I, eighth leaf in the bud ; st, st, its stipules.
Fig. 198.—?, outer face of eighth leaf ; st, st, its stipules spread out.
ON THE STRUCTURE OF BUDS 125
stipules, because they are dead. The third pair are
larger, and to them belongs the first leaf of the bud
(fig. 194). The fourth pair are longer than the third.
Their leaf-blade is subulate, and about one-third as long
as their stipules. Sometimes it dies in winter. The
fifth pair are sometimes nearly as long as the bud.
The third leaf-blade belongs to them, and i3 consider-
ably larger, though but slightly longer. The fourth leaf-
blade is nearly as long as its stipules. The seventh pair
are about half the length of their leaf- blade, and thin.
The ninth and tenth pairs are less than half the length
of their leaf-blade.
This represents the average composition of a bud
at midwinter; but there is considerable variation in
the relative lengths of the leaves and their stipules.
Sometimes the third leaf belonging to the fifth pair of
stipules is nearly equal in length to the latter, but it
may be the fourth, fifth, or sixth leaf which attains this
size. The first two or three leaves never attain any
great size, even if they live through the winter. Their
stipules, however, are always largely developed, and
more or less cemented together with a viscid gum,
obviously for the protection of the leaves. The leaves
that attain a large size in the bud retain their pre-
dominance after expansion, while the small outer ones
remain relatively small.
The axillary buds are smaller and somewhat dit-
ferently constructed. The outer covering is short, broad,
126 BUDS AND STIPULES
and open on the side towards the stem ; the second is
longer, and narrower in proportion.
Several of the species secrete a gum, which forms
an additional protection to the bud.
the lime (Tilia)
In the Lime (Tilia vulgaris) (PI. I. fig. 1) the
pseudo-terminal and lateral buds are very similar.
They are generally lop-sided or tumid on one side,
owing to the thickening of the small outer scale,
particularly along the midrib. The true apex of the
shoot becomes disarticulated and falls off. The bud
does not lie opposite the centre of the leaf, but a little
on one side. As already mentioned (ante, p. 9), this
occurs in other trees, as, for instance, in the Beech and
Hornbeam (fig. 11). The consequence is that the
pseudo-terminal bud has a scar on each side of it —
one that of its leaf, the other that of the fallen shoot.
The scales of the winter-bud are arranged on
alternate sides of the bud, the leaves being alternate
and distichous. The outer scale overlaps the second at
the base, but is little more than half its size, though
two-thirds the length of the bud. The first two are
coriaceous, glabrous, and not accompanied by a leaf;
they are also obtusely and slightly carinate. Some-
times one stipule of the outer pair is absent.
The next two are larger, more nearly equal in
size, roundly cordate; showing an inclination to
ON THE STRUCTURE OE BUDS 127
become petioJate owing to their being much wider
than their insertion. They are glabrous, as long as the
l)inl, rolled round three-fourths of it, the outer one
covering the same extent as the inner, which is more
membranous, except at the tip. They are accompanied
by a small, conduplicate, silky leaf.
The next pair are broadly elliptic, unequal, mem-
branous, and more or less silky on both surfaces. The
larger scale or stipule is always the outer of the pair.
The second leaf is much larger than the first, densely
silky, with unequal parts, the narrower one being
uppermost. The edges of the leaf are always directed
under the larger stipule ; and it will be noted that
the direction of the leaf and the larger of each pair
of stipules are altered in each succeeding set. This
is due to the alternate and distichous arrangement
of the leaves.
The fourth pair are oblong-elliptic, covering three-
fourths of the bud, as in succeeding cases, and more
silky than the previous pair on the outer face, but
otherwise similar. The leaf is as long as the next
younger pair of stipules, and lies in a convex manner
over them.
The fifth pair are oblong, and the outer stipule
covers less than half of its fellow. The sixth pair are
more unequal and very much smaller. The seventh
pair are oblong-lanceolate and very small ; while the
eighth pair are still smaller and membranous.
128 BUDS AND STIPULES
The next younger leaf in each case lies beneath its
own stipules, and in that position corresponds to the
opening left uncovered by the previous and older pair.
None of the pairs of stipules completely surround the
bud.
The outer scales are often of a rich crimson (PL I.
figs. 1, 2), and the next few sometimes of a brilliant ruby
with greenish tips. When the buds first open the
leaves, as is the case in other trees — for instance, the
Beech, Hornbeam, Elm, &c. — turn downwards, as-
suming, as Mr. Henslow has pointed out, the attitude
of some leaves when asleep, and probably for the same
reason, namely, to expose a less surface to the sky
during the cold nights of spring.
the birch (Betula alba)
In the Birch also the terminal shoot perishes,
and the apparently terminal bud is really axil-
lary.
If an apparently terminal bud is carefully examined
in winter it shows four scars at the base. Two of
these are large, and are those left by the death of the
terminal shoot and the leaf respectively. The two
smaller ones, which are not always easy to see, are
those of the stipules of the fallen leaf.
The bud itself is ovoid-oblong, obtuse, glabrous, or
with a few cilia at the margins of the scales, and deep
ON THE STRUCTURE OF BUDS 129
brown. The outer scales represent stipules the leaf-
blades of which are not developed.
The first pair are slightly unequal in length, and do
not overlap at any point nor surround the whole of the
bud. The second pair, when spread out, are almost semi-
orbicular, rounded at the apex, and slightly unequal
in length, the inner one being the longer and over-
lapped at the base by its fellow at both edges. They
cover a considerable portion of the bud, owing to
their width. The third pair are as long as the bud,
covering the whole of the younger members and over-
lapping at their edges. They are more membranous
than either of the one or two preceding pairs, and are
more or less covered with a viscid gum. They are
also slightly narrowed at the base. The fourth pair
are more decidedly boat-shaped than the previous
one, but are still imbricate. The first leaf generally
occurs in connection with the third or fourth pair of
stipules, but inside of, and covered by, them. It is
rhomboid, acute, shortly petiolate, serrate, thinly pube-
scent, glandular, viscid, and concave. The fifth pair
are somewhat smaller than the fourth, but otherwise
similar, as is their leaf. The latter is much more
involute in bud, though neither strictly convolute
nor conduplicate. Its form is doubtless due to the
abrupt arrest of the younger members of the bud;
for the fourth and fifth pairs of stipules, together
with the first and second leaf belonging to them re-
K
130 BUDS AND STIPULES
spectively, are greatly in advance of those that follow.
The sixth pair of stipules and the younger members of
the bud they enclose will show a reason for the second
leaf being partly involute, so as to occupy the space.
According to Henry (18, 309), the outer scales are
the stipules of the last leaves of the previous year. The
description given above, however, is, I believe, the
correct one.
the BEECH (Fagus si/lvatica)
The bud of the Beech (figs. 199-210) is more
complicated. It is elongated, spindle-shaped, half to
three-quarters of an inch in length; on the outside
are four closely imbricating rows of stipules, arranged
apparently in opposite decussate pairs. I say appa-
rently, because, as the leaves are alternate, it is pos-
sible that each pair of these stipules are really alternate,
though so compressed as to appear to be opposite.
The first pair (fig. 200) are small, triangular, and
pointed. The five following are also triangular, each
rather larger than the preceding and more convolute,
till they almost enclose the upper part of the bud.
The lower ones are brown and coriaceous ; the upper
membranous, and furnished with numerous straight,
longitudinal, parallel, slender veins running from the
base to the apex. The covered parts are white, the
exposed brown. The upper ones are fringed with long,
sc.st.
St. l- st
Fig. 207.
Fig. 210.
The Beech (Fagus sylvatica).
PIG. 109.— Winter-bud. Km. 900.-— First or lowest pair of stipules.
Km. 201.— Sixth pair of stipules overlapping at the corners. Fig. 202.— Eleventh
pair of stipules, showing how one is rolled within the other : /, position when-
the leal should be, though it is yet absent. Fid. 203.— Diagrammatic trans-
verse section of the stipules, showing the extent to which they overlap.
rn:. 20*.— The bud after eleven pairs ot stipules have been removed ; Z, the first leaf;
.f the outer one of the twelfth
pair. Pro. SOB. - ■tipnles. I'i<;. 244.— Second ditto.
Fig. 245.— Third ditto. Fig. 24C— Fourth ditto.
142 BUDS AND STIPULES
stipules ; and in this respect they closely resemble those
of the Elm. At the base of the bud the persistent
base of one or two leaves, that fell in autumn, may be
found sheltering, it may be, axillary buds. These can
easily be recognised by the scars of the three vessels
(fig. 236). One obvious difference between the buds
of the Whitebeam and the Elm is that the scales
of the former are arranged in five ranks, while those
of the latter are in two ranks, the difference being
dependent upon the phyllotaxy.
The first scale (fig. 237) is semicircular and slightly
erose at the apex, but otherwise entire. The second
(fig. 238) is several times as large, and obtusely cari-
Dftfce. The third scale (fig. 239) shows three ribs or
nerves, and is about as long as the bud before growth
is resumed in spring. The fourth is similar. The
fifth scale (fig. 240) of a good-sized terminal bud (from
which the sketches were made) was 3-ribbed, more
membranous, greenish and trifid at the apex, thus dis-
closing the true nature of the scales, namely, a combina-
tion of the base of the petiole and the stipules. All
the scales are rather firmly glued together by means
of a viscid gum secreted from a cluster of orange-
coloured glands situated close to the base on the inner
face. The sixth is similar.
The seventh scale (fig. 241) is still more membra-
nous, more faintly 3-nerved, very unequally trifid, and
enclosing three-quarters of the bud. The eighth is
ON tin: structure of buds 143
tridentate, and shows a transition towards the true
nature of its component parts.
The ninth scale (fig. 242) is oblong, much narrower,
and trifid. The middle tooth is subulate-terete, sub-
fleshy, and red, being more like a petiole than in any-
previous scale. The three nerves are now closer together
and directed into the petiole. The side lobes or stipules
are rounded. The fifth to the ninth scale inclusive
are more or less woolly on the inner face.
At the tenth node a normal leaf occurs (fig. 243).
It is oblong-obovate, plicate, with ascending nerves,
serrate, woolly, and slightly shorter than its oblong or
spathulate membranous stipules, which show one or
two nerves.
The leaf-blade (fig. 244) at the eleventh node is
lanceolate, and slightly longer than its linear, 1 -nerved
stipules. The third leaf-blade (fig. 245) at the twelfth
node is shorter and narrower, as are its stipules. The
fourth leaf (fig. 246) at the thirteenth node is smaller,
and shows a slight variation in being wider at the
middle. The fifth, sixth, and seventh leaves, with
their stipules, are gradually smaller, but otherwise
similar.
The actual number of scales in the buds of the
Whitebeam varies a good deal, being fewer in the
small buds, as well as in the large ones containing an
inflorescence. The outer scales are coriaceous, the
inner ones membranous. The bud sketched was ex-
144 BUDS AND STIPULES
amined towards the end of April, when the inner
scales had commenced to push out at the apex.
The leaves are covered, especially on the under side,
with white felt. Whatever may be the position of the
branchlet, they stand quite upright, with the under
sides outwards (PI. II. fig. 5), so that they form a
succession of intensely white pillars.
Protection by Connate Stipules
elm (Ulmus)
The buds of the common Elm (Ulmus campestris)
(figs. 247-260), like those of preceding species, are
covered and protected by scales, but there is an impor-
tant difference. Each scale in the Beech or Oak
represents a stipule. In the Elm each scale represents
a pair of stipules. This is shown by the position and
arrangement of the scales. The leaves are in two rauks,
as in the Beech. Hence, as there are two stipules to
each leaf, it follows that if each scale corresponded to a
stipule they must be in four ranks, as, in fact, they
are in the Beech (fig. 199). Those of the Elm, however
(fig. 247), are in two rows, showing that each consists
of two connate stipules.
This is further suggested by the fact that they are
very often bifid at the summit, as is also shown in
(fig. 256) — a further indication of their double origin.
The young leaf, moreover, is situated, not between two
ON THE STRUCTURE OF BUDS
145
scales, as in the Beech, but within and opposite the
middle of the often bifid scale.
The outer four stipular scales are coriaceous, dark
brown, brittle, more or less ciliate towards the apex.
247 248 249 250
i st o.st.
251
252
253 254
l. St. _ o.st.
259
260
Elm (Ulmus campestris).
Fig. 247. — Terminal bud, showing seven scales.
Fig. 248 —The first scale Fig. 249.— The second scale. Fig. 250.— The third scale.
Fig. 251.— The fourth scale. Fig. 252.— The fifth scale. Fig. 253.— The sixth Male.
Fig. 254.— The seventh scale. Fig. 255.— The eighth scale.
I'm;. 256. — The ninth scale, showing fusion, which is unusual.
Fig. 257.— Members at the tenth node : o.st., outer stipule with a portion removed to
show the leaf, I, which comes next in order ; i.st., inner stipule.
Figs. 258-200.— Members at nodes 11 to 13 ; o.st., outer stipule : I, leaf ; i.st., Inner
stipule. All are separated to show outline.
Owing to their being connate, however, the single
piece occupies the central position of the leaf, the
blade of which, if present, would be between them.
These four scales do not elongate in spring, being prac-
tically dead ; they often split at the apex into four or
five teeth.
L
146 BUDS AND STIPULES
The first scale (fig. 248) is widely triangular and
generally sharply cuspidate. The second (fig. 249) is
nearly orbicular, deeply concave, and covers a conside-
rable portion of the bud. The third (fig. 250), fourth
(fig. 251), and fifth (fig. 252) are more oblong, gradu-
ally longer, each covering a large portion of the bud and
overlapping the scale next above them. The fifth is
more membranous and pubescent, remains alive during
winter, and elongates on the resumption of growth in
spring. It is strongly or copiously ciliate, particu-
larly above the middle. The sixth (fig. 253) is longer,
but otherwise similar.
The seventh scale (fig. 254) in an average bud is the
longest, covers about three-quarters of the bud, and
being folded over or round the top of the bud, all the
scales that follow are slightly shorter. The eighth
(fig. 255) is more narrowed at the base. All these scales
from the fifth onwards are furnished with longitudinal
slender veins, running almost parallel from base to
apex.
The ninth scale (fig. 256), in the bud from which
the sketches were made, was divided halfway down, one
lobe overlapping the other. Each half was furnished
with a distinct midrib, with a few more slender veins
proceeding from it. Other buds contained several more
or less divided scales. Here we have evidence of these
scales being made up of two stipules.
The tenth node of the same bud bore two perfectly
ON THE STRUCTURE OF BUDS 147
distinct, broad, oblong stipules, with a leaf between
them (fig. 257). Other buds showed that the fifth
or often the seventh scale had reached this stage ;
so that individual buds vary according to size, vigour,
and other circumstances. The stipules have a midrib
and overlap one another. All the leaves are condupli-
cate, alternate, and distichous ; and as they lie against
the sides of the axis, with their edges to the sky, it
follows that when figured on a flat surface their edges
appear to be turned in opposite directions at each alter-
nate leaf.
The eleventh pair of stipules (fig. 258) in the same
bud were very unequal, the outer being the larger,
oblong, and having the edges of the leaf lying beneath
it as usual. The inner stipule was oblong-subulate.
The stipules of the twelfth pair (fig. 259) were also un-
equal, the larger one being oblong-lanceolate and the
smaller linear. The leaf-blade equalled its stipules in
length. The thirteenth pair (fig. 260) and the four-
teenth were unequal in length and width, but both
linear. The leaf-blades of these two were longer than
their stipules, but the slender apex is sometimes, at
least, crumpled up beneath the apex of the stipule.
The larger of the two stipules of each leaf lies on
the upper side of the branches or shoots bearing them.
The leaves are all conduplicate in bud, acuminate, and
penninerved, with closely approximate nerves. The
two parts of the leaf are unequal, but this is scarcely
L 2
148
BUDS AND STIPULES
discernible in the bud. The broader part lies next the
axis, as in the Lime.
Henry (18, 308) regards the outer scale as a combi-
nation of the leaf-blade with the two stipules. I see,
however, no sufficient reason for this view.
As the leaves come out the shoot
curves down, and the stipules form arched
hoods over the young leaves. They are
often bright pink and very pretty.
In the Wych Elm (Ulmus montana)
the construction and arrangement of the
bud (fig. 261) resemble that of the Com-
mon Elm, but the double character of
the outer scales was more clearly shown
Fig. 361.— Bus in the specimens I examined. Fig. 262
gives the four outer scales. The inner
ones pass gradually into pink, from a greyish green base.
The young bud (PL III. fig. 1) is in a line with
Fig. 262.— Outer Scales of Bud of Wych Elm.
the branchlet, but as it expands it turns down-
wards and hangs at right angles to it (PL III. figs. 2-4).
When the young shoot has reached the stage shown in
ON THE STRUCTURE OF BUDS
149
PI. III. fig. 4, any slight touch is sufficient to detach
the outer scales. A few days later the pink scales also
begin to wither and fall off. The leaves then rise up
again and assume their permanent position.
the plane (Platanus)
The case of the Plane (Platanus orientalis) is also
very interesting. If the base of the leaf-stalk be
263 264
267 268
Winter-bud of Plane (Platanus orientalis).
Fig. 263.— st, outer or first stipular scale, entire.
Fig. 264.— tf, second stipular scale, glandular and slightly hairy, entire.
1 in. 265. — st, third stipular scale, very hairy, with a minute opening at the apex.
Fig. 266.— st, fourth stipular scale, very hairy, open at the apex ; I, the first leaf.
Fa;. 207. — st, lifth stipular scale, now much shorter than the bud and open at the
top, showing an inflorescence,/' ; I", the second leaf, which is slightly 5-lobed.
PIG. 268. — st, sixth stipular sheath, now reduced to a narrow rim, hairy, and here
spread open ; V", the third leaf, which is 5-lobed, with the two small lobes
folded on the back of the leaf.
examined, it will be found, as already mentioned
(ante, p. 6), to form a regular cap, protecting the bud
(fig. 7). After the leaves have fallen the winter-buds
are covered by several cap-like stipules, the leaves of
which are not developed. The outer cap is brown
or reddish browu, and has a gummy secretion on
150 BUDS AND STIPULES
its inner surface, besmeariug the bud, as in the
Horse Chestnut, but only in the very early stages.
As the bud swells the outer cap becomes ruptured,
and appears then like a deeply concave scale, which
is glabrous or nearly so. This cap is followed by
others, which attain a somewhat larger size before the
expanding bud causes them to split ; they are densely
covered with brown hairs externally and glabrous
internally.
Fig. 263 represents the terminal bud of the leading
shoots, and also of the lateral spurs or short twigs,
covered with a conical, fluted, glabrous, reddish-brown
cap, consisting of stipules which are connate to the
very apex ; the latter is slightly lateral, and all the
ribs or veins terminate there.
Inside the first stipular cap comes a second (fig. 264),
thinly hairy, dotted with dark glands and completely
covered with a viscid, resinous secretion ; the veins
terminate at the apex.
The third cap (fig. 265) is also entire, but densely
covered with glossy rich brown hairs ; the latter have
three to six very short, spreading branches at the very
base, and consist of two to six joints, resembling a
bamboo or fishing-rod, the joints becoming more slender
towards the apex.
The fourth cap (fig. 266) is shorter, widely open at
the apex, and provided with an ovate leaf at its base
externally ; both cap and leaf are covered with brown
hairs.
ON THE STRUCTURE OF BUDS 151
In the bud figured the fifth (fig. 267), sixth (fig. 268),
seventh, and eighth scales show a leaf with the free
portion of the stipules forming auricles, and the connate
portion forming a short cylindrical sheath. The number,
however, differs slightly in different buds.
Inside the above in all the
large buds comes a spike of
heads or clusters of fruits (/,
fig. 267), the heads so arranged
as to form a conical mass inside
the various caps and short
cylinders formed by the stip-
ules.
THE SPANISH CHESTNUT
(Oastanea vesca)
The scales which protect
the bud of the Spanish Chest-
nut (Castanea vesca) (fig. 269)
are also connate stipules ; this
is indicated by their being
frequently indented at the
apex. The outer one is dry and
brown. The second scale (fig. ^J^^ZJ^Z
269) is longer and greener. second scale detached, x 4.
Its true character is shown not only by the indentation
at the summit, but by the presence of a rudimentary
bud at the base, which is situated, not at the side, as
152 BUDS AND STIPULES
it would be if the scale were a single stipule, but
opposite the centre.
The following pairs of stipules are separate, hairy,
and about as long as their leaf, which is conduplicate,
but the sides do not touch as they fold over the inner leaf.
The next leaf and its stipules are similar. The fifth pair
of stipules are narrower, and rather shorter than their
leaf. The following stipules become quite narrow. The
leaves are conduplicate.
Protection of the Bud by Connate Stipules
belonging to different leaves
In the previous cases the two connate stipules were
the pair belonging to a single leaf. In the Hop
(Humvlus Lupuhts) (figs. 270, 271) the two stipules
which have coalesced belong to two different leaves.
The stipules are large, develop early, and cover not
only the rest of the bud, but their own leaves also.
Henry (18, 268) regards the stipules covering the
bud of the Hop as representing the stipules of a pair
of leaves which are otherwise undeveloped. The ex-
planation above given seems, however, to be more in
accordance with the facts.
A similar case is afforded by those species of Stellatce
(Galium) which have leaflets in whorls of four.
In Elatine Alsinastrum, also, the stipules are united
each to the neighbouring stipule of the opposite leaf,
so that the stipules equal the leaves in number.
ON THE STRUCTURE OF BUDS
153
CONIFERS
The buds of Conifers are constructed on a very
different plan.
That of the Scotch Fir (Pinus sylvestris) (figs. 274,
275) is covered by brown, elongated scales, which are
st*
Fig. 270. Fig. 271.
End of Shoot of the Hop.
Fit;. 270. — Stipules in their natural position, x3.
Fig. 271. — Lower stipules turned back, exposing a protected leaf (i.) with its
axillary bud (ft) on each side of the stem ; st\ st'\ st\ stipules at successive
nodes.
spirally arranged on the axis, and represent the primary
leaves. They rest on a pedestal or base (fig. 273), which
in the winter is green, and from which they are easily
stripped off, leaving a whitish scar.
154
BUDS AND STIPULES
The bud may be divided into three parts. The
lower, which occupies from one-fifth to one-tenth of
the length, is somewhat narrower than the rest. No
needles are developed on this part of the bud. The
Sc
Fig. 272.
o
Fig. 273.
Scotch Fir (Pinus sylvestris).
Fig. 272. — Fragment of terminal bud representing seven tiers of scales of the winter-
bud, x 6 ; He, three scales with their fringed membranous margin, the rest have
been removed ; 6, persistent bases of scales ; I, buds of secondary leaves in the
axils of the primary.
Pig. 273.— A detached scale-base.
middle portion is the longest, and when the brown
portion of the primary leaves has been stripped off
has, from their spiral arrangement, very much the
ON THE STRUCTURE OF BUDS
155
appearance of an elongated cone. At the base of each
pedestal i- a small axillary bud, bearing the secondary
leaves or needles in pairs. The brown, terminal part of
the primary leaves is thrown off in spring, and these
secondary leaves form the ' needles.'
The brown, primary leaves are thicker towards the
centre, and thin off towards the edges. They consul
of diverging fibres connected by a thin membrane.
Fig. 274. Fig. 275.
Scotch Fir (Pinus sylvestris).
Tig. 274. — Terminal bud ; sc, bases of primary leaf-scales which have been removed,
revealing the axillary foliage-leaf buds ; tb", terminal bud of next year ; lb,
lateral bud.
Fig. 275. — Apex of branch, x 2 ; f, terminal bud ; a, axillary buds at the base of the
terminal ; I, base of pair of secondary leaves or needles.
Towards the edges the fibres turn suddenly backwards,
and are frayed at the edges, forming an interlacing tissue,
which helps to strengthen the bud (fig. 272). These
scales are very numerous. Some of the outer ones are
truncate (fig. 275). These are followed by a few that
are triangular, subulate, acuminate. Succeeding scales
156 BUDS AND STIPULES
pass quickly from triangular to more decidedly sub-
ulate forms, which are more or less revolute at the tip.
They are followed by a few more which are linear,
with a subulate base, and revolute at the tip.
These scales with revolute tips are followed by a
dense mass of others which are subulate-linear, acumi-
nate, straight, and closely adpressed to the bud.
If a large terminal bud is taken, and the scales
removed, it will be seen that the bud includes the whole
of the plan of growth for the two succeeding years (fig.
274). The scales themselves are the primary leaves of
next summer's shoot ; and their obovate, persistent bases
constitute the persistent scales upon the primary axis.
In the axils of these persistent portions, which are
green in winter, we find the axillary buds which go to
form the secondary shoots upon the resumption of
growth in spring. In those buds containing male
catkins, the latter are equivalent to axillary shoots, and
occupy the lower portion of the axis of the bud ; while
the perfect leaves are similarly accommodated, but
higher up the axis of the large resting winter-bud.
At the apex of this bud we find two or more rela-
tively large ones, which are the resting buds of the
succeeding year. The scales covering them are already
testaceous, but await the following summer before
making further progress.
Thus the primary leaves of two seasons' growth
take part in the composition of the winter-bud.
ON THE STRUCTURE OF BUDS
157
In the Spruce Fir (Picea excelsa) the winter-buds
(fig. 276) vary greatly in size, those at the apex and
279
280
281
282
283
284
U
285
Spruce Fir (Picea excelsa), x 3.
Fig. 276. — Apical and two lateral buds ; p.l., pedestals of leaves after the
green portion has been removed. Fig. 277.— Normal and perfect leaf : /,leaf :
p, pedestal ; b, basal portion decurrent upon the axis. Fig. 278. — Slightly
modified small leaf ; I, leaf; p and b, pedestal and base merged in one another.
Fk;s. 279,280. — Leaves now modified to triangular acuminate scales with a
midrib. Figs. 281, 282.— Succeeding forms of rales. PIGS. 283, 284, 285.—
Inner scales after they have elongated, about the middle of April : /, I, in
Rga, 283, 284, would seem to represent the lamina, surmounting elongated
pedestals: the same portion in Fig. 285 is hooded over the apex of the bad ;
the lower portions are membranous and transparent.
158 BUDS AND STIPULES
immediately beneath it being strongest on the leading
branches ; they are also the first to resume growth in
spring. All are covered with numerous scales, which
consist of modified leaves. The actual number of scales
varies greatly, according to the size of the bud. The
accompanying figures would represent buds and scales
about the middle of April, aftergrowth has recommenced.
The outer scales are the most coriaceous, and elongate
slightly or not at all ; the inner ones are transparent
and membranous, elongating considerably in spring.
The true leaf (fig. 277) consists of a lamina, which
becomes disarticulated (when about to fall) from a short
persistent portion or pedestal, surmounting a basal
portion which is decurrent upon the axis. Fig. 278
shows a small, slightly modified leaf — a form which
occurs but sparingly.
The basal portion of the bud is covered with broad,
triangular, acuminate scales (figs. 279, 280), with a
more or less evident midrib, which seem to consist of
the whole leaf modified. These are followed by a few
oblong, obtuse, or subacute scales (figs. 281, 282) that
are still coriaceous, but elongate slightly in spring in
the case of the inner ones.
The innermost scales (figs. 283, 284, 285) are as
long as the bud, or nearly so ; but after the resump-
tion of growth they soon extend beyond the coriaceous
ones, keeping pace for a time with the elongating axis,
and completely enclosing the young true leaves. These
ON THE STRUCTURE OF BUDS 159
inner scales elongate chiefly in the lower portion, which
seems to correspond to the pedestal. They are, on the
whole, more or less spathulate, but vary in form, and
the apical portion seems to correspond to the lamina,
because there is generally a trace of a joint or articula-
tion. This apical portion is slightly more coriaceous
and browner than the long and very membranous lower
portion.
Some of the inner scales are more or less evidently
trifid (fig. 284) or tridentate, the lateral lobes appear-
ing to correspond to the shoulders seen below the
pedestal of the normal and perfect leaf. The inner-
most scales (fig. 285) are suddenly widened at the apex,
forming a hood or cap rolled round the apex of the
bud and completely covering and protecting the young
leaves.
CYCADACE.E
In Cycas (Cycas revoluta) one tier of leaves is pro-
duced every year, all developing simultaneously. The
bud is covered with a mass of imbricate scales. The
latter are subulate, elongate, ending in a spine, dilated
and triangular at the base, densely covered with
a pale brown, woolly felt, erect or incurved in bud,
ultimately spreading with age, but persisting for many
years. Thus two sets of leaves are developed every
year, each tier duly alternating.
In Zamia also (Zamia Fischeri) the buds are pro-
tected by numerous scales.
160 BUDS AND STIPULES
CHAPTER VI
ON THE FORMS OF STIPULES
Though stipules do not show such endless differences
in form as is the case with leaves, nevertheless they
present an immense variety.
They may be orbicular, as in Tropceolum ciliatum
(fig. 312) ; semi-orbicular, as in Guaiacum officinale
(fig. 30) ; ovate, as in Passiflora racemosa, Hop (fig. 47),
and Abutilon megapotamicum ; obovate, as in Bucklandia
(fig. 190) ; oblong, as in Leea (fig. 188) and Alder (fig.
145); elliptic, as in Hazel Nut (fig. 212) ; spathulate ;
lanceolate, as in Paronychia serpyllifolia and Pyrus
japonica; linear, as in Bisanihus (Hamamelideo?) and
Ficus infectoria; filiform, as in Turkey Oak (Quercus
Cerris) ; subulate, as in Mahonia and several species of
Helianthemum; sagittate, as in Latliyrus pratensis (fig.
299) and L. maritimus ; semi-sagittate, as in Latliyrus
latifolius (fig. 300) and L. grandiflorus ; reniform, as in
Vallea (Sterculiacece); triangular, as in Ceanothus rigidus ;
boat-shaped, as in Populus nigra (fig. 192); palmately
lobed, as in Croton ; laciniate, as in Trigonella laciniata ;
pinnatifid, as in several species of Croton, Medicago and
ON THE FORMS OF STIPULES 1G1
Mi'lilotus- pinnatipartite, as in Viola tricolor (fig. 27),
Passiflora pinnatistijmla, and Pomaria glandulosa; or
palmatipartite, as in Altluea rosea, A. ficifolia, Ptero-
spermtnn ac-erifolium, Sec. *
In texture they may be foliaceous, as in the Hearts-
ease ; membranous, when thin, flexible, and almost trans-
parent ; scarious, when dry and coriaceous, as generally
in the Beech and Hornbeam; spinous, as in Robinia
(fig. 34) ; cirrhose, when produced into tendrils, as
in Smilax.
In many cases the stipules are very small, sometimes
quite minute, as in Hymenanthera (fig. 28), a plant
belonging to the Violet family. The Holly is described
in Bentham and Hooker's ' Genera Plantarum ' as exstip-
ulate, but (fig. 29) there are minute black points at the
base of the leaves, which appear to represent stipules.
In others they are very large, as in the common Pea
(Pisum sativum) (fig. 26), Lathyrus maritimus (fig. 296),
and BucJclandia (fig. 190).
Many plants have stipules of different forms.
The stipules covering winter-buds are often different
in form from those of the subsequent leaves (see, for
instance, figs. 215-235).
Where stipules serve as bud-scales there is generally
a series of different forms, from those of the outer
scale to those of the ordinary leaf.
In the Thorn (Crataegus Oxyacantha) (fig. 286) the
stipules on the leaves of the short later.nl spurs and those
M
162
BUDS AND STIPULES
at the very base of the elongating shoots are minute and
toothlike, or subulate, soon becoming brown and falling
early. Those on the upper part of the elongating shoots
Fig. 286. — Leaves of Hawthorn.
vary from unilateral, falcate, serrated, small but folia-
ceous organs, to large, half-cordate, simply or doubly
serrate, shortly stalked, foliaceous, much-reticulated
ox THE FORMS OF STIPULES .163
organs, with the principal nerves radiating from the
base of the lamina and passing into the principal teeth.
Thus there are at least three distinct types of stipules.
These differences are probably connected with the
differences in the shoots. These may be described as of
two kinds, namely, those which develop into more or
less lengthy, leafy shoots, which go to increase the height
and breadth of the tree, and those which form short
lateral spurs. The latter are very numerous, forming
dense rosettes of leaves, and produce clusters of flowers
in profusion in adult bushes and trees. Owing to the
crowded state of their leaves, the bases of their petioles
occupy the whole, or very nearly the whole, of the sur-
face of the short axis, thus leaving little or no space for
stipules. The lower or outer leaves are very small, and
entire, or tridentate, or trifid, with short petioles. Very
often these have no trace of stipules. The inner or
upper leaves of these rosettes are better developed, with
elongated petioles, so as to enable them to extend beyond
and occupy the space between the short ones. This is
obviously a provision to expose every leaf to light. The
stipules of these longer-stalked leaves vary from mere
points to subulate or linear, small, brown organs, which
being relatively functionless after the expansion of the
leaves, soon shrivel up and fall away.
At or near the base of the elongated leafy shoots
fairly well-developed leaves occasionally occur, which have
no stipules : but as a rule the stipules in this position are
m a
164
BUDS AND STIPULES
also well developed (fig. 286). As these shoots elongate
and become vigorous, the internodes become longer, and
the leaves and stipules larger. The latter, indeed, become
287
288
RlBES SANGUINEUS!.
Fhi. J*:.— Outer bud-scale with three vascular bundles ; stipules indicated by lateral
teeth at the tip.
Fig. 288.— Inner bud-scale with broader membranous margin.
Fig. 289.— Intermediate form between bud-scale and leaf. F STUM I I ID]
can be relied on, many of the specimens thus affected
are from the richest moist forest regions of tropical
America. They never appear to affect the whole of the
stipules of any one bush, varying in degree of develop-
ment in the several pairs of stipules of the same branch,
but affecting special forms and tinges of colour, from an
ivory-white to a livid purple, for each species.' ,
The Common Bulls-horn (Acacia cornifjera), described
by Belt (21), bears hollow thorns, while each leaflet pro-
duces honey in a crater-formed gland at the base, as
well as a small sweet, pear-shaped body at the tip. In
consequence it is inhabited by myriads of a small ant,
which nests in the hollow thorns, and thus finds meat,
drink, and lodging all provided for it. These ants are
continually roaming over the plant, and constitute a
most efficient bodyguard, not only driving off* the leaf-
eating ants, but, in Belt's opinion, rendering the leaves
less liable to be eaten by herbivorous mammals.
Bower (22) describes another interesting case of a
myrmecophilous plant — Hiimboldtia laurifolia. The
stipules consist of two parts: a lower, sagittate part,
with four to six glands on its upper face, and an
ovate-lanceolate part, with one or more glands, on the
lower surface ; they originate from two outgrowths at
the base of the leaf-stalk below the leaflets.
K. Schumann (23) figures the bladders, inhabited
by ants, at the base of the leaves of Duroia saccifera
and Remijia physophora, both tropical South American
192 BUDS AND STIPULES
members of the family Rubiacece. He does not, how-
ever, regard them as stipules, but as ' sac-like
outgrowths of the blade.' They lie at the base of the
leaf, near the middle nerve.
In Korthalsia also, a Malayan Palm, the base of the
petiole is swollen into a sort of ocrea, in which a species
of ant makes its home.
Spiny stipules also occur in Porlieria, an American
genus, a member of the family Zygoj)ltyllacea^ in Paliiirva,
one of the Rhamnece, &c.
Nectariferous Stipules
Kerner was, so far as I am aware, the first who
called special attention to the importance of extrafloral
nectaries in the economy of plants. He, however,
suggested that their function was to keep ants away
from the flowers. The real object seems, rather, to be
to attract ants, which, as already mentioned, protect
the plant from various enemies — from caterpillars,
leaf-cutting ants, &c. Every fruit-grower in Java
knows how ants protect the plant from fruit-eating
bats (Pteropus). Nectaries are often situated on the
calyx, and the presence of ants protects the flowers
from being bored through at the base by bees. Some
species of Smilax also have winged petioles, in which
ants make small nests.
As an illustration of glandular stipules may be
ON THE SUBSIDIARY USES OF STIPULES 193
mentioned those of the Vetch (Vicia sativa), which
secrete honey, especially when the sun shines.
The stipular glands of Viburnum have been already
described (ante, p. 40).
In the Myrtacece, again, we have cases of glandular
stipules. In Psidium Cattleyanum they consist of one
to four subulate processes, or of one rather membranous
and colourless, trifid ortridentate piece. They scarcely
Fig. 312. — Trop^olum ciliatum, showing leaf and stipule. Nat. size.
seem to be protective, but the outer process is generally
tipped with a globule of fluid.
The remarkable Peruvian species of Tropceoluvtv
already mentioned (T. ciliatum) has curious ciliated and
apparently gland-tipped orbicular stipules (fig. 312).
Glandular stipules also occur in some Lythrariece,
Leguminosce, Linacece, Onagrariece, Cucurbitacece, Dros-
eracece, Balsams and Cruciferce.
0
194
BUDS AND STIPULES
As an Assistance in Climbing
There are two ways in which stipules may assist in
this respect, viz. (1) by being developed into tendrils,
or (2) into more or less reversed spines.
The case of the tendrils of Smilax
is one which has occasioned much
discussion, but I agree with Tyler
(24) that the embryological, together
with the anatomical, characters in-
dicate that in Smilax the tendrils
are true stipules, found in connection
with the sheathing petiole.
In Paliurvs australis (fig. 313), a
Southern European plant belonging
to the same family as our Buckthorn,
the stipules are spiny, but the two
stipules of each leaf are different in
form and serve for different purposes.
Those on the upper side of the shoots
are long, subulate, and straight ;
Fig. 313. — Paliurus those on the lower side are shorter
riTHoOTPORIION and deflexed. The former appear
5''Pfte-Ps'\SSyalbuds to serve as a protection against
orS>^3 browsing quadrupeds ; while the
&"», the third scar in hooked ones also assist the plants
the onler of arrangement,
showing that the phyi- to climb or scramble up among other
lotaxy is i. Nat. size.
shrubs and bushes.
In Machcerium also, a tropical American genus of
ON THE SUBSIDIARY USES OF STIPULES 195
Legumino8ce , the stipules are often converted into
thorns, which are in some cases bent backwards so as
to aid the plant in climbing.
As Reserves of Nourishment
In Ghmnera, according to Reincke (25), stipules
serve as reserves of nourishment.
As Holders of Rain
Another use of stipules is to hold rain, as, for
instance, in some species of Thalictrum, Viola, and
Polygonum.
The leaflets of Thalictrum (T. simplex) are so
arranged as to catch most of the raindrops ; they are
not wetted, however, by the rain, which runs off and
down the petiole to the cup formed by the stipules.
The stipules are fringed at the edge, which also assists
to retain the moisture.
In some species of Viola also — for instance, Viola
tricolor (Pansy) and the little yellow V. biflora — the leaf
and leaf-stalk have a central furrow, down which the
water runs to the stipules, by which it is retained.
The ocrea or sheath of the Polygonacece also serves
in some cases for the same purpose. This is well seen
in the large species, for instance, of Rumex and Bheum.
They will retain water for several days after the rain
has ceased. It is, however, gradually absorbed.
In support of this view I may refer to the case of
o2
196 BUDS AND STIPULES
the Teasel (Dipsacus), where the bases of the petioles
are expanded and connate, thus forming a large cup,
which generally contains water. It has been suggested
by Kerner that this water forms a sort of moat, which
protects the flowers from ants and other creeping
insects. On the other hand, Mr. Francis Darwin
suggests that insects, &c, are drowned in the water, and
thus supply the plant with animal food. He has de-
scribed certain curious protoplasmic threads, emitted
by some of the cells, which he suggests may serve to
absorb the nourishment thus supplied.
As Supports
It is probable that, as Grevillius (2G) has suggested,
the ocrea of Polygonum may be of use in strengthening
the stem at the internodes, which are points of rapid
growth, and consequently of weakness. He observes
that this can be tested by removing the sheath, and then
shaking the stem, when it will be found that it is
especially liable to give way at the internode.
197
CHAPTER VIII
ON THE NATURE OF STIPULES
In ordinary parlance, when we speak of a leaf we
often think only of the leaf-blade. The leaf-blade is,
however, in reality only part of the leaf. The complete
leaf is generally described botanically — as, for instance,
in Asa Gray's excellent ' Structural Botany,' Bentham's
1 Handbook of the British Flora,' &c. — as consisting
of (1) the leaf-blade, (2) the stipules, and (3) the
petiole or stalk, to which I think, for reasons which
will be presently given, we ought to add (4) the
leaf-base. Vines (27) describes the leaf as divisible
into three transverse parts — upper, median, and
lower — corresponding to the blade, stalk, and base.
The base may, he considers, be either more or less
sheathing, or developed laterally, forming stipules.
The stipules, however, seem to occupy the same
position in relation to the base as the blade or leaflets
do to the stalk. If, therefore, the blade is considered
as forming a division separate from the stalk, I should
rather regard the leaf as consisting of four parts :
the blade, stalk, stipules, and base.
Perhaps, however, the more philosophical view would
198 BUDS AND STIPULES
be to regard the leaf as consisting of two parts —
(1) the base, with or without foliar expansions, the
stipules ; and (2) the upper part or petiole, with or
without a foliar expansion, the leaf-blade.
Sometimes all four divisions are present, as in the
Hose ; sometimes the stipules are absent, as in Maples ;
sometimes the leaf is sessile, the stalk, stipules and base
being undeveloped, as in Gentians; sometimes the blade
is absent, and its functions are performed by the flattened
petiole, as in most of the Australian Acacias ; sometimes
the stipules perform the function of the leaf-blade, as in
Lathijrus Aphaca (fig. 294).
That Helianthemum vulgare (fig. 22, p. 20) has stipules
and It. (elandicicm (fig. 23, p. 21) has none is clear and
simple enough, but there are many cases in which the
presence or absence of stipules is far from being so easy
to determine, and which have been the subject of much
difference of opinion amongst botanists.
For instance, the Composites generally (Daisies,
Chrysanthemums, Dandelions, Lettuces, &c.) are said to
be exstipulate, but in some the petioles are dilated at
the base into appendages which can scarcely be
distinguished from stipules.
In some Crucifers, as, for instance, in Cardamine
imjyatiens, some of the lower leaves have rounded and
thickened auricles, which in the upper leaves become
prolonged into subulate, obtuse, falcate processes clasp-
ing the stem. These are often called stipules. They
ON THE NATURE OF STIPULES
199
correspond to the auricles of other Crucifers which are
continuous with the margin of the leaf.
The Umbellifers (Carrot, Parsnip, Parsley, &c),
again, have the petioles flattened and broad, often
forming a sheath. In some the upper or smaller
part of the sheath becomes detached. When this has
Fig. 314. — Leaf of Parsley.
Fig. 315. — Leaf of Ostruthium.
proceeded sufficiently far the free lobes may fairly be
called stipules. Indeed, it is obvious that there may
be every intermediate gradation between a species
with a merely flattened petiole and one with true
stipules. Nay, such transitions may and do occur in
the same plant, and even in the same bud.
200
BUDS AND STIPULES
I have figured leaves of three members of this
family to illustrate this relation between leaf-sheath and
stipule. In the Parsley (fig. 314) the sheath is quite
entire; in Ostruthium (fig. 315) there is a distinct
shoulder on each side ; while in Fool's Parsley (^EtJiusa
Cynapium) (fig. 316), a common British species, the
shoulder has grown out into a small but distinct stipule.
Fig. 316. — Leaf of 2Ethusa.
Speaking of Canarium, Bentham and Hooker say
(' Genera Plant.,' i. 324) : ' Folia exstipulata, vel pinnulis
inferioribus sessilibus stipulaeformibus, imparipinnata,'
and again, ' Foliola infima Canarii interdum stipulas
simulant' (p. 321).
ON THE NATURE OF STIPULES 201
The small primary leaves of the Mistletoe have been
mistaken by some authors for stipules.
Aristolochia elegans, while really exstipulate, has a
small cordate, membranous, subsessile leaf in the axil,
which resembles a single axillary stipule ; sometimes a
pair are present. Close examination shows that this stip-
ule-like process is really the first leaf of an axillary
axis or bud. It clasps the main axis with its auricles, and
has two buds in different stages of advancement lying
between it and the petiole of the leaf in whose axil it
occurs. The small leaf belongs to the larger and more
advanced bud.
The early unfolding of the first pair of leaves of an
axillary bud may often give the appearance of stipules.
For instance, in Tutsan (Hypericum ATidroscemum) the
leaves are opposite and exstipulate, but the first two
leaves of the axillary branch, before any further growth
of the bud takes place, stand right and left above the
base of each leaf, and by a careless observer may be
taken for stipules.
The genus Lotus (Bird's Foot Trefoil) is quinque-
foliate. The lower folioles have been sometimes re-
garded as leaflets, sometimes as stipules. Bentham and
Hooker, in the ' Genera Plantarum,' say, ' Folia 4-5-
foliolata, foliolis integerrimis 3 ad apicem petioli
confertis, 1-2 juxta caulem stipulas simulantibus.'
Speaking of the corresponding organs in Tetragono-
lobus, Norman says that they ' par leur structure, leur
202 BUDS AND STIPULES
coloration, leur forme et leur position, sont entierement
differentes des folioles, et s'harmonisent tout a fait
avec les stipules que Ton trouve dans la plupart des
Legumineuses ' (28).
The same may also be said of the allied genera
Dorycnium, Bonjeania, &c.
Cambessedes, however, maintains that the true
stipules of Lotus and the other genera mentioned are
two minute glandular elevations at the base of the leaf.
The Leguminoscv, to which these genera belong, are
as a rule stipulate ; so that if this view is correct we
have an interesting case in which the stipules have
dwindled away, and their function is performed by the
lower leaflets, which have to some extent wandered
away from their usual position in order effectively to
take on this new duty.
Again, the tendrils of Cucumbers (Cucurbitacece)
and Smilax have been regarded by some botanists as
stipules, while this has been denied by others ; and the
same difference of opinion has existed with reference
to the ligule of grasses.
I shall presently return to some of these doubtful
cases.
Helianthemum guttatum is a very interesting species.
As Dr. Stenzel (29) points out, the lower part of the shoots
bears lancet-shaped leaves without stipules. Nearer the
flower-buds the leaves tend to become smaller, and have
stipules. These are linear, and attached quite at the
ON THE NATURE OF STIPULES 203
base of the leaf. Frequently, however, leaves occur
with only one stipule, while at the other side of the
leaf is a tooth-like projection, into which a weak nerve
enters, which is wanting on the other side of the leaf,
or rather is replaced by the nerve of the stipule. In
some cases there is no tooth, but the side of the leaf
which has no stipule is broader than the other. Some-
times, again, there are no stipules, but the leaf has a
tooth on each side, which may cut into the leaf almost
to the base.
Stenzel therefore regards the so-called stipules of
II. guttatum as being really leaflets. In that case, how-
ever, all the stipules of Helianthemum must be so re-
garded, and the case appears to be one which requires
further study. The same argument might be advanced
in the case of many undoubted stipules; e.g. Pansy.
There has also been a good deal of difference of
opinion in the case of the Elders (Sambucus). In 8.
canadensis , Tyler (21) says that stipules are typically
developed.
Bentham and Hooker (' Gen. Plant.' ii. 3) say, 'Petiolo
basi nudo glanduloso v. foliolis stipulseformibus aucto.'
In our Common Elder (S. nigra) the leaves are
sometimes exstipulate, sometimes (fig. 31, p. 26) have
minute stipules ; on the other hand, the Dwarf Elder
(S. Elndus) has small leaflets at the base of the leaf-
stalk, which, in Bentham's words, ' look like stipules.'
In the Black Bryony (Tamus communis), there is at
204 BUDS AND STIPULES
the base of the leaf a small cylindrical process, generally
turned backward, which was regarded by Cauvet (30),
and I think with justice, as a stipule. Colomb ques-
tions this, on the ground that these processes receive
no nerves. As already mentioned, however, this does
not seem to me a sufficient reason for excluding them
from the category of stipules.
Norman also regards the axillary glands of Cmciferw
and Lythrariece as rudimentary stipules.
Another question which has been much debated is
whether stipules are to be regarded as (1) dependent
on leaves, as (2) autonomous and independent organs,
or (3) as an integral part of the leaf.
As a supporter of the view that stipules are a de-
pendence of the leaf I may quote Van Tieghem (31), who
considered stipules to be leaf-lobes. He regarded every
leaf with stipules as a compound leaf. Baillon (32) also
quotes Viburnum as ' une bonne demonstration de ce
fait que les stipules sont des lobes de feuille.' Kichard
also was of the same opinion. Schleiden appears to
have doubted whether stipules had any claim to special
significance. Asa Gray (33) describes stipules as c ap-
pendages or adjuncts of a leaf,' and Bentham (34) as
'appendages at the base of the leaf-stalk.'
As a matter of fact, leaflets have, no doubt, often
been taken for stipules.
However difficult the discrimination between leaflets
and stipules may sometimes be, the real difference is
ON THE NATURE OF STIPULES 205
well shown in species where the leaf-development is
basipetal — that is to say, the upper leaflets are formed
first, and the lower ones in succession. Now, if stipules
were ordinary leaflets, they would in such cases be formed
last, while, as a matter of fact, they make their appear-
ance with, or even before, the first leaflets.
A strong reason against regarding stipules as mere
subordinate structures dependent on the leaf-blade is
that they arise so early, often, indeed, before the leaf-
blade with which they are associated, as, for instance, in
the Pea (fig. 26, p. 23), Buchlandia (fig. 190, p. 122), &c.
A further reason against regarding stipules as mere de-
pendent parts of the leaf is, that while in many cases
leaves have no stipules, in others stipules take the place
of leaves — using the word, that is to say, in the usual
sense.
Thus, in Lathyrus Apliaca (fig. 304, p. 179) there are
no leaflets, the leaf-blade being replaced by a tendril,
and the ordinary function of the leaf-blade is performed
by two enlarged stipules.
Again, in some species of Adesmia (fig. 311, p. 187),
a South American leguminous genus, leaves are present
only on the lower part of the long, straggling branches,
the upper part bearing stipules only, which gradually
pass into bracts.
It seems, then, incorrect to regard stipules as mere
dependencies of the leaf-blade with which they are
associated.
206 BUDS AND STIPULES
I now pass to the second view, that of those botan-
ists— as, for instance, Lindley (35), Agardh (36), and
Clos (37) — who have regarded stipules as autonomous
organs, analogous to and independent of the leaf.
Steinheil (4) maintained that each lobe was virtually a
leaflet, and even a leaf. Turpin's opinion was that ' Les
stipules caulinaires sont des feuilles distinctes, reduites
a l'etat rudimentaire ' (39). In support of this view
it has been urged that some plants have stipules but no
leaves, and that in others the stipules appear early,
often, indeed, it has been said, before the appearance ol
the leaf. This, however, is not strictly correct. No
doubt they do often appear before the commencement
of the leaf-blade, or of leaflets. In pinnate leaves the
stipules are in some cases formed before the first
leaflets. The rudiment of the leaf-stalk, however,
as a rule appears before the stipule.
Another strong reason for regarding the stipule as
a part of the leaf is the fact that the woody fibres
which supply the stipules are, as a rule, if not always,
derived from the foliar bundles. It has, indeed, been
supposed that the Rubiacece and Violacece form an
exception ; but Colomb has shown that this is a
mistake (19). Take, for instance, the case of the Pansy
(Viola tricolor). The stipules (fig. 317, S) are large, more
or less deeply laciniate at the sides. The central
woody tissue of the stem (T _B, fig. 318) sends out three
fibres, L, L and M, which pass into the leaf-stalk. The
ON THE NATURE OF STIPULES
207
two outer ones, Land .L, soon branch, the larger division
passing into the leaf, while the smaller one, ir, supplies
the stipule.
Fig. 319, representing a section of the stem of
Galium Aparine, shows a similar arrangement : the
Fig. 317. — Leaf of Pansy. Fig. 318 — Tkansverse Section of Stem
£, stipule. of Pansy at a Node, showing leaf
sage of vascular bundles into pas-
and stipules (S).
foliar bundles, L, L, soon after leaving the central pith
emit branches, s, s, which supply the stipules.
Colomb defines stipules as appendages ' inserted
on the stalk at the base ot the leaf, the fibres of which
are exclusively derived from the corresponding foliar
bundles ' (' insere sur la tige, a la base de la feuille, et
dont tous les faisceaux proviennent exclusivement des
faisceaux foliaires correspondants ').
208
BUDS AND STIPULES
But there are some undoubted stipules which con-
tain no fibres, as Colomb himself says in another place,
speaking of Polygonum.
The history of the early development of the young
stipule shows, indeed, I think conclusively, that it
cannot be regarded as a separate and independent
organ. We must, then, I think, adopt the third view,
viz., that stipules are an integral part of the leaf.
Fig. 31(J. — Tkansvi kse Sec-
tion of Stem of Galium
Aparine at a Node.
Fig. 320. — Plane (Platanus
orientalis). Nat. size.
a a, axis ; P, petiole of leaf ; Sh, sheathing
or concave base, covering the axillary
bud ; 0, ocrea ; L 0, lamina of ocrea.
I now proceed to consider certain organs which
must be included amongst stipules, although they
diverge widely from the ordinary form and arrange-
ment.
The Ocrea
The sheath or ocrea of the Planes, Polygonum, &c,
is generally, and, I think, correctly, regarded as a form
ON Till: NATURE OF STIPULES
209
of stipule. In the Plane (fig. 320) the relations of the
ocrea to the stem and the leaf-stalk have been well de-
Fig. 321.
Fig. 322.
E,
Fig. 323. Fig. 324.
Plank (Platanus).
scribed by Colomb, from whose account the following
figures are taken. Fig. 321 represents a section of the
210
BUDS AND STIPULES
twig a little below the joint, and shows seven wood}'
fibres emerging from the central cylinder, which will
enter the petiole. These may be termed ' foliar' fibres.
The fibre A is first detached, then B and G, C and F,
and lastly D and E, which are only beginning to
emerge when A is already completely detached. The
fibres as soon as they separate from the central cylinder
Fig. 325.
Fig. 326.
Plane (Platanus).
bend towards A (fig. 322) . A little higher (fig. 323) a slit
appears, which is the commencement of the petiolar
cavity in which the bud is sheltered. The main fibres,
D and E, are approaching C and F, but have sent off
lateral fibres, D' and W. A little higher (fig. 324) D and
E are still nearer C and F; at the lower part another
ON THE NATURE OF STIPULES
211
slit has appeared — the commencement of the detachment
of the sheath. Still a little higher (fig. 325) the petiole
has detached itself from the sheath, but the two together
have a single cavity. The fibres D and E, before entering
the petiole, sent out several branches, D1, D2, D3, and E\
E2 and E3. Still higher we have the section shown in
fig. 326. A parenchymatous band, MN, now separates the
Fig. 327. Fig. 328.
Polygonum lapathifolium.
cavity of the petiole P from that of the sheath T, which
encloses the stem. The sheath, therefore, is an append-
age inserted on the node, and receiving fibres derived
from the foliar fibres, before the latter have left the
branch.
The sheath of the Castor Oil plant (Ricinus) is
constituted in the same manner, and, like that of the
Plane, all its fibres are derived from the foliar bundles.
p2
212
BUDS AND STIPULES
The stem of Polygonum (e.g., P. lapathifolium) is
somewhat octagonal, with a central cylinder of the same
form. Some little way below the leaf eight fascicles
(fig. 327, A to H) detach themselves from the angles
of the central octagon, and, passing outwards, turn
towards the fascicle A.
Fig. 329.
Polygonum lapathifolium.
The fascicle E divides, each branch curving round
towards A, and emitting as it does so a branchlet, Elt e.
When the bundles have separated themselves from
the central cylinder, and nearly reached the bark, a slit
appears, which, passing from C to G (fig. 329), and gradu-
ally extending (fig. 330), finally separates the sheath
entirely (fig. 331) from the central axis. The original
ON THE NATURE OF STIPULES 213
Bi «
Fio. 331. —Polygonum
LAPATHIFOLIUM. FlG. 332.— OCREA (o) OF POLYGONUM.
Fig. 333.— Potamogeton lucens.
214 BUDS AND STIPULES
fibres, A toil, are now (fig. 328) all collected in the part
which will become the stalk of the leaf, the sheath
being supplied by fibres thrown off from the branch lets.
This sheath is known as an ocrea. Fig. 332 shows its
natural position.
The development of the ocrea of the Pondweed
(Potamogeton) (fig. 333) follows a very similar course.
Stipular Tendrils
In the Melon and other Cucurbitacece the tendril is
regarded by some botanists as a stipule. This view is
strongly supported by the fact that it is lateral, and
that two tendrils occasionally occur, one on each side of
the leaf. On the other hand, they are seldom at the
same level, and the tendril is derived from a vascular
bundle remote from that which produces the leaf. It is,
moreover, separated from the petiole of the latter by
buds. These considerations have led other botanists to
regard the tendril as representing a leaf reduced to
one or more of its nerves. The differences of opinion
have been very remarkable. De Candolle and others
have regarded them as stipules ; Gasparini and Braun.
as leaves ; Link, as superfluous branches ; others as
abortive peduncles ; others as roots. Payer has pointed
out that when there is no tendril the leaf receives three
fibro-vascular bundles. If there is a tendril, one goes to
the tendril, and two enter the leaf ; while, if there are
two tendrils, each receives a bundle, and there is only
ON THE NATURE OF STIPULES 215
one for the leaf. This supports the view that the
tendril corresponds to a stipule.
The tendrils of Smilax will be referred to under the
next heading.
Monocotyledons
There has been much difference of opinion as to
whether Monocotyledons have stipules. De Candolle
stated without any hesitation or qualification that ' Les
stipules n'existent dans aucune plante monocotyledone.'
Others, however, have been of a different opinion. The
tendrils of Smilax and the ligule of Graminece have
been regarded by many botanists as true stipules.
The tendrils of Smilax arise in the same manner as
stipules, being lateral outgrowths of the base of the
young leaf. They must, I think, be regarded as stip-
ules, though it will be seen from the subjoined note l
1 The tendrils of Smilax have been considered as representing
two lateral leaflets of a compound leaf by Von Mohl ( Ueber den Bau
mid das Wuulcn der Ranken und Schlingpflanzen, 41, 1827) ; Lind-
ley (LUrod. to Botany, Ed. 2, 118, 1835) ; Link (EUm. Phil. Bot.
Ed. 2, i. 478, 1837) ; St. Hilaire (Legons de Bot. 170 and 854, 1840) ;
Le Maout (Atlas de Bot. 23, 1846), and Duchartre (Art. ' Vrille ' in
Diet. Vniv. Hist. Nat.).
Mirbel (EUm. de Physiol, et de Bot. ii. 680, 1815) ; Treviranus
(Physiol, der Gewachse, ii. 138, 1838) ; Seringe (EUm. de Bot. 175,
1841) ; De Candolle (Thdorie EUment. Ed. 3, 321, 1844) ; Trecul
(Ann. Sci. Nat. ser. 3, xx. 295, 1854), and Lestiboudois (Ball. Soc. Bot.
Fr. iv. 745, 1857), believe these organs to be stipular. It is the
opinion of Clos that they are neither leaflets nor stipules, but a
double lateral prolongation of the cellulo-vascular elements of the
petiole. Colomb (19, 33) regards the tendril of Smilax as a demi-
ligule.
216 BUDS AND STIPULES
that in this case, as in that of the Cucumber, there has
been, and is still, much difference of opinion.
The ligule of grasses is another doubtful case, but
must, I think, be regarded as a form of stipule.
The leaf of a grass may be divided into three
parts — the sheath, the blade, and the ligule. The
sheath embraces the stem ; at the point where it termi-
nates are two blades, one, generally called the leaf,
making a broad angle with the stem, the other being
a prolongation of the sheath, and known as the ligule.
It must, therefore, I think, be admitted that some
Monocotyledons do possess stipules ; and having regard
to the great differences presented by the two classes,
we cannot, I think, be surprised that the stipules of
Monocotyledons generally differ considerably from those
of Dicotyledons.
STIPELLiE
The leaflets of pinnate leaves have sometimes a
small foliaceous expansion at their base, and for these
De Candolle proposed the appropriate name of ' stipels.'
Stipellae do not, like stipules, run generally through
a whole order, but are scattered sporadically in certain
genera and small groups of genera. Fig. 334 shows
an instance in a leguminous plant.
Effect of Removal of Leaf
Goebel (9, 837), and subsequently Kronfeld (40),
have made some interesting experiments as to the effect
ON THE NATURE OF STIPULES
217
on stipules of removing the leaves belonging to them.
In some cases, especially in the Bean (View, Faba) and
Pea (Pisum sativum), the result was that the stipules
were considerably increased in size ; but in the major-
Fio. 334. — Leaf of Desjiodium canescens, showing stipels
at base of leaflets.
ity of cases — Willow, Nettle, Polygonum, Sida, Rosa,
li'iihus, Clover, Chrysanthemum, &c. — no such effect was
produced, and in the Apple sometimes only.
The following table gives the figures in one set of
218
BUDS AND STIPULES
Goebel's experiments. In each case two seeds of the
same weight were sown together : —
Normal Plant. After Removal
of Loaf
red 141 mm. . 239 mm.
172 „
561 „
165 „
920 „
92 „
98 „
84 „
242 „
107 „
351 „
86 „
276 „
68 „
361 „
2nd
3rd
Plant 2. „ 1st
2nd
3rd
4th
5th
It is probable, however, that more effect would be
produced if the leaf had been extirpated at an earlier
stage.
In other species no corresponding effect followed.
The suppression of the stipules in Lathyrus Aphaca, for
instance, had no effect in transforming the tendrils into
leaf-blades.
Cotyledons very rarely have stipules. This may,
perhaps, be because they are sufficiently protected by
the fruit and seed coverings. There are, indeed, a
few exceptions, as, for instance, in Genipa clusicefolia
(figs. 335-338), where, however, they are very small.
They are interpetiolar, united into one ovate, acute
piece, colourless and subscarious.
They occur also in Psijchotria (fig. 339), another
genus of Rubiacece, a family of which one of the most
constant characters is the presence of stipules. Another
instance is afforded by Thelygonum.
ON THE NATURE OF STIPULES
219
Clos, in an interesting and elaborate memoir (38), has
attempted to show that as a rule bracts are modified
stipules. De Candolle in 1858 expressed this opinion
as regards Begonia ; and Clos, amongst other species,
refers to Cinchona officinalis ■ and angustifolia, Isertia
Fig. 335.
Fig. 33G.
Fig. 337.
Genipa clusi^efolia.
Fi<:. 335.— Longitudinal section of seed, x 2| ; C, cotyledon; It, radicle ; En, endosperm.
Fig. 336. —Transverse section of seed, x 2\ ; C, cotyledon.
Fig. 887. — Germinating seed with side of seed and one cotyledon removed, x4;
T, testa ; En, endosperm ; St, stipule ; O, surface of ground.
coccinea, Berteria guianensis, Spermacoce calyptem,
Cissus tamoides, Rondeletia obovata, &c. Most of his
references, however, are to old and somewhat vague
figures. Cinchona officinalis has small but well-
marked stipules at the base of the bracts, and the same
is the case in Rondeletia obovata. If bracts really
Fig. 338.— Seedling
of Genipa
Cluslefolia..
Nat. size.
S, stipule.
N V
ON THE NATURE OF STIPULES
221
(•.presented stipules they would, as a rule, be in pairs,
which is not the case. Moreover, Clos's view could not,
of course, apply to the bracts of exstipulate species.
Fig. 339. — Seedling of Species of Psychotria.
8, ~tipule.
Nat. size.
222 BUDS AND STIPULES
I think, then, as already stated, we must conclude that
stipules are an integral part of the leaf; that leaflets are
portions of the leaf-blade ; and that, if we consider the
leaf-blade as a part separate from the petiole, we must
regard the leaf as consisting of four parts, viz. :
1 . The blade.
2. The petiole.
3. The stipules.
4. The base.
Perhaps, however, it would really be more consistent
with the facts to regard it as composed of two parts :
1. The upper part, or petiole, generally provided
with a leaf-blade ; and
2. The base, which also is often provided with a
pair of stipules.
223
CHAPTER IX
SUMMARY
The Bud
The bud is a young shoot — that is, a stem or branch
with its rudimentary leaves closely packed together.
It is normally situated either at the summit of the stem
or in the axil of a leaf.
The young leaves require protection against too
great cold, heat, drought, or moisture, too vivid light,
and the attacks of animals and plants. This is effected
in various ways.
The scales which protect the winter-buds fall into
at least eight categories :
1. Pedestals of last year's leaves, as in Pyras Aria.
2. Stipules of last year's leaves, as in Magnolia.
3. In many cases the young leaves are protected
by modified leaves, as, for instance, in Willows and
Lilac.
4. In others the protection is afforded by leaf-stalks,
the leaf not being developed, as in Maples and the
Sycamore ;
224 BUDS AND STIPULES
5. In others by the leaf-base, as in the Rose, Portugal
Laurel, &c. ;
6. In others, again, by stipules, as in the Beech,
Oak, Elm, Poplar, &c. ;
7. In others by pairs of stipules, as in the Elm,
Spanish Chestnut, &c. ;
8. Or by two connate stipules, not, however, belong-
ing to the same leaf, as in the Hop.
In many species the protection thus afforded is
further enhanced (1) by the presence of a gummy or
resinous secretion, as in the Horse Chestnut, Plane,
Alder, Conifers ; or (2) by furry hairs, as in the Plane,
Horse Chestnut, Vine.
Stipules
Stipules are normally more or less leaf-like structures
at the base of, or just below, and one on each side of, the
leaf-stalk. They are very variable in size and appear-
ance.
A typical leaf may either be considered to consist of
four parts :
1. The leaf base.
2. A pair of stipules.
3. The leaf-stalk or petiole.
4. The leaf-blade, which for shortness is often called
the leaf.
Or, and perhaps more philosophically, of two parts :
1. A leaf-base, which may or may not develop
stipules.
SUMMARY 225
2. A petiole, the upper part of which normally ex-
pands into a leaf-blade.
In some cases, as in the Rose, all four are developed ;
in others one, two, or even three of these constituents
may remain undeveloped.
As a general rule stipules serve to protect the bud,
and in most cases shelter younger leaves only ; but in
some, especially in quickly growing plants, as, for
instance, the Pea, Hop, Vine, &c, they envelop the
petiole and blade of their own leaf.
In some cases the stipules of the last leaf of a year
protect the young leaves of the following season, as,
for instance, in some Magnolias, Petteria, Poplar.
In most cases, however, these stipules drop off, and
the outer, covering scales are an integral part of the
bud. Where there are stipules, the outer leaves often
develop no leaf-blades (Oak, Beech, &c).
When stipules serve, and serve only, to protect the
bud, they are generally caducous, and drop off soon
after the leaves have expanded.
In the Oak, Beech, Hornbeatn, &c, each of these
outer bud-scales is a single stipule.
In some cases, as in the Elm, Spanish Chestnut, &c,
each consists of the two connate stipules belonging to
the same leaf.
In others, as in the Hop, each scale consists of the
two stipules on one side of the shoot. The two halves,
therefore, belong to different leaves.
Q
226 BUDS AND STIPULES
The general function of stipules being to protect
the younger leaves, their presence or absence depends
in great measure on the need for such protection.
Hence we may almost lay it down as a general rule
that where the leaf-stalk is broad and covers the bud
there are no stipules, and that where it is too narrow
to protect the bud stipules are present.
The protection of the bud is, indeed, the general
function of stipules, though by no means the only one.
We may summarise the uses of stipules as follows :
1. To protect the bud.
2. To help in performing, or even, as in Lathyrus
Aphaca, to perform, the function of leaves.
3. Sometimes they are hardened into spines, and
thus serve to protect the whole plant, as in Robinia
(so-called Acacia).
4. Sometimes they form hooks, and assist the plant
in climbing (Paliurus).
5. Sometimes they are developed into tendrils, as in
Smilax.
6. Sometimes they secrete gum, which helps to
protect the bud ;
7. Or a sweet secretion, which attracts wasps, &c,
as in some species of Viburnum.
8. Sometimes they serve to hold water, as, for
instance, in some species of Viola, Thalictrum and Poly-
gonum.
MMARY 227
9. Sometimes they act as reserves of nourishment,
as in Gunner a.
10. Sometimes they serve for a support to the stem.,
as in some species of Polygonum.
The view here suggested seems to apply well both
to the cases where the stipules are very short-lived,
and also to those in which they are very persistent.
When they serve, and serve only, to protect the leaves
to which they themselves belong, they often fall off
when the leaves themselves expand. On the other
hand, as a general rule, they protect the following leaf
or leaves, as, for instance, in Magnolia, Liriodendron,
and other Hagnoliaceaj. When the stipules of the
terminal leaves of one year protect the next leaves,
which do not emerge till the following year, they are
much more persistent than the leaves themselves. Both
cases sometimes occur in the same family.
This, then, is the answer I should give to M.
Vaucher's question (see p. 20), and the presence or
absence of stipules is not determined, I think, as sug-
gested by De Candolle, by any question of general
symmetry, but rather by practical considerations con-
nected with the wants and requirements of the plants.
No doubt, also, there are some cases in which stipules
have ceased to be of any use to the plants, and are
merely the persistent rudiments of organs which per-
formed a useful purpose to the ancestors of the existing
Q2
228 BUDS AND STIPULES
species in bygone ages, and under different circum-
stances.
The Fall of the Leaf
Having traced up the leaf from its earliest rudi-
ment, it remains, in conclusion, to say a few words about
its final stages.
The fall of the leaf (41) is by no means a simple
process or a mere case of death. In the first place, the
chlorophyll-substance is too valuable to be lost and
thrown away. Sachs ! has satisfied himself that it passes
out of the leaf, down the petiole, and thus migrates into
the persistent parts of the plant, and is stored up for
future use. With the general disappearance of the
cell- contents the protoplasm and cell nuclei are dis-
solved, the chlorophyll corpuscles lose their normal
outlines, the starch disappears, and the colouring matter
changes, leaving in many cases a large number of small,
bright yellow granules, to which the yellow tints of
autumn are due. In many cases the cell-sap becomes
bright red. Sachs has been able by chemical examina-
tion to follow the materials (and especially the starch),
and also the most valuable chemical materials (espe-
cially the potash and phosphoric acid), down the petioles,
into the twigs, where they are preserved, evidently to
nourish the growing buds of the following spring.
While these changes are taking place a new layer of
cells is formed across the base of the petiole (fig. 340).
1 Flora, 1863, p. 300; Phys. of Plants, tr. by H. M. Ward, p. 318.
SUMMAltV
229
These cells eventually adhere less and less closely
together, so that at last the slightest touch or the
gentlest wind brings the leaf to the ground. That this
is not a mere case of death of the leaf, but, on the
contrary, is a vital process, we may easily convince
ourselves by breaking a branch during summer. In
Fig. 340. — Longitudinal Section through the Junction of Stem
and Leaf of the Horse Chestnut in Autumn.
a, parenchyma forming the outer cortex of the twig ; b, external cork layer of the
same ; c and e, parenchymatous tissue at the base of the leaf-stalk ; d, separating
layer, the continuity of which is already broken in the upper part.
that case it is killed, the new layer of cells is not
formed, and the leaves remain firmly attached to the
twig.
It is also of interest to notice how plants utilise the
fact of the temporary nature of their leaves. Leaves
share with the bark (also transient) the functions of the
excretory organs of an animal. In their cells are de-
230 BUDS AND STIPULES
posited the waste products of the chemical life-processes,
to be got rid of when the leaf falls or the bark peels.
A leaf which has served its time and then been dropped
contains quantities of calcium oxalate, resinous and
gummy matter, and, like the bark also, alkaloids, such
as nicotin, them, and other nitrogenous excreta.
Climate has, naturally, a great influence on the
length of time during which leaves remain attached.
Where autumn is prolonged the leaves also last long.
Thus, for the neighbourhood of Naples, excepting when
winter sets in unusually early, Tenore quotes the end of
November for the leaf-fall of the Walnut, Ash, Lime,
Oak, and Poplar, and states that the leaves of the Apple,
Beech, Elm, and Birch often last till the end of De-
cember, and the Cherry is evergreen. Foliage generally
will keep longer in a damp, sheltered spot than in dry,
sunny, exposed positions, and longer after a wet than a
dry summer. Trees do not lose their leaves at the same
time : not only are Oaks and Elms still green when the
Horse Chestnuts and Limes are almost bare, but some
individual trees retain their leaves longer than others of
the same species. Apart from conditions of climate or
weather, each species has its own peculiarity in this
regard. This may sometimes be due to the fact that
species now growing together in one country have come
originally from somewhat different climates. A plant
may have contracted the habit through long generations
of shedding its leaves early or late, as the case maybe, and
SUMMARY 231
retain the habit under changed conditions. De Candolle
explains early leaf-fall in some cases by introduction
from an extreme climate where it would be necessary,
and instances the Walnut, introduced from Armenia.
Another question is, Do the plants which come into
leaf early in spring lose their leaves early in autumn,
and are the late leafers also tardy as regards defoliation ?
Or are the early leafers late to lose their leaves ? The
hawthorn hedges are among the first to show signs of
green in the spring, and among the last to lose their
foliage in the autumn. The Horse Chestnut buds have
burst when the Oak and Ash are grey as at midwinter,
but the latter retain their leaves the longer. We must
remember, too, that the Ash gets its flowering over before
leafing, while in the Chestnut the leaf-buds are the first
to expand. To try and settle this point De Candolle
made a resume of four years' observations in Belgium, in
which twenty-eight species or varieties were concerned.
He made four lists : A, the early leafers ; B, those with
an early leaf-fall ; C, late leafers ; D, those where the
fall is late. Each list contains about thirteen names.
Two, Spircta sorbifolia and Lilac, are common to A and B ;
that is, out of thirteen early leafers only two lose their
leaves early. Four are common to A and D : leaf early
but fall late. Two, Walnut and Oleditschia ferox, occur
in both B and C, having an early fall, though leafing
late; and four are late in leafing and have also a late
leaf-fall. It is therefore evident that the time of leaf-
232 BUDS AND STIPULES
fall does not depend on the time of bursting of the buds.
De Candolle also quotes observations on individual
trees. In many species, like Horse Chestnut, Beech,
Elm, &c., trees growing side by side, planted at the
same time, and subjected to the same external condi-
tions, neither come into leaf nor lose their leaves simul-
taneously. These facts of idiosyncrasy, he says, are con-
stant. They recur in the same manner year after year,
even when the differences in time are only three days.
Of three old trees in the court of a country house at
Frontenex, the owner stated that for years they followed
the same order of succession at both epochs : those which
were first to leaf were also the earliest to lose their
leaves. A Chestnut in the gardens of the Tuileries from
its habit of early leafing is known as the Vingt Mars ;
and M. Henri Vilmorin states that, compared with the
other Chestnuts in the gardens, it keeps its leaves beyond
the mean time of leaf-fall. M. Vilmorin also observed
thirty-four Horse Chestnuts, 150 years old, in a planta-
tion on his own property at Verridres in 1876 and 1877.
He found that those which were the first to lose their
leaves in 1876 were in the same category next year,
with slight differences as to order. Six of those which
were the first to put out leaves in spring were late to
lose them in autumn, while five others were early in leaf
and early in losing leaf. He concludes that the two
phenomena have no regular relation. Similar observa-
tions on the Beech and Elm led to the same conclusion.
SUMMARY 233
Evergreen leaves differ greatly in length of life.
Some remain on the tree for several years ; for instance,
in the Scotch Fir, three or four years; the Spruce
and Silver Fir, six, seven, or even eight; the Yew,
eight ; Abies Pinsc^o, sixteen or seventeen ; Arau-
caria, even longer. It is true that during the later
years they gradually dry and wither; still, being so
long-lived, they naturally require special protection.
They are, as a general rule, tough, and even leathery.
Thus, then, I have endeavoured to answer Vaucher's
question — to explain, at any rate, in some cases the
presence, the uses, and the forms of stipules, and the
structure of buds in some of our common trees, shrubs,
and herbs.
If I shall have induced any of my readers to look
at them for themselves in the coming spring they will,
I am sure, be amply rewarded.
They will often be reminded of Tennyson's profound
remark about Nature :
So careless of the single life,
So careful of the type she seems,
and will be more and more struck with wonder and
admiration at the variety and beauty of the provisions
by which Nature preserves these tender and precious
buds from the severity of winter, and prepares with
loving care and rich profusion for the bright promise
of spring and the glorious pageant of summer.
INDEX
Abies, 233
Abutilon, 160, 171
Acacia, 17, 26, 29, 35, 80, 186,
189, 191, 198, 226
Acer, 44. See Maple
Achimenes, 19
Actinidia, 77, 79
Adesmia, 186, 205
Adventive buds, 17
iEsculus. See Horse Chestnut
^Ethusa, 200
Ailanthus, 58
Alder, 92, 98, 160, 224
Alnus. See Alder
Aloe, 65
Alstonia, 85
Althaea, 161
Amentaceoe, 33
Amicia, 52
Ampelopsis, 121, 122
Amygdalaceae, 82
Anchusa, 92
Apocynaceae, 85
Apple, 217, 230
Araucaria, 233
Arenaria, 37
Aristolochia, 201
Aroids, 65
Asclepias, 58
Ash, 10, 68, 107, 230, 231
Astragalus, 31
Aucuba, 47, 55
Azalea, 63
Azara, 171
Azinia, 72, 189
Balsam, 193
Barberry. See Berberry
Bauhinia, 190
Bean. See Vicia
Bedstraw, 28, 59
Beech, 16, 22, 25, 27, 67, 68, 130,
165, 189, 224, 225, 232
Begonia, 4, 18, 71, 219
Berberis. See Berberry
Berberry, 35, 72, 81
Berteria, 219
Betula. See Birch
Birch, 9, 128, 230
Bird's-foot trefoil, 201
Bird's-nest orchid. ' See Neottia
Bixineoa, 171
Black bryony. See Tamus
Black poplar, 28, 123
Bonjeania, 202
Boraginere, 92
Borago, 92
Box elder. See Negundo
Bramble, 63
Brassica. See Cabbage
Broom, 81
Bryophyllum, 17
Bucklandia, 122, 160, 101, 205
Buckthorn, 90, 91
Buds, 1
Bulls-horn, 191
Cabbage, 11
Calythrix, 34
Canarium, 200
Gapparis, 189
236
BUDS AND STIPULES
Caprifoliaceae, 42, 73
Cardamine, 17, 198
Carpinus. See Hornbeam
Carrot, 199
Caryophyllaceas, 33, 37
Castanea. See Chestnut
Castor oil, 211
Catasetum, 19
Catha, 172
Ceanothus, 160
Celastrineje, 172
Centaurea, 59
Cerastium, 37
Cerasus, 48
Cheiranthus. See Wallflower
Cherry, 64, 230
Chestnut (Spanish), 68, 161, 224,
225, 229
Chilocarpus, 95
Chrysanthemum, 198, 217
Cinchona, 219
Cissus, 122, 219
Cistus, 36, 37
Citharexylum, 75
Clematis, 82
Clover, 54, 173, 217
Colletia, 17
Composites, 73, 198
Conifers, 8, 92, 153, 224
Cornus, 90
Corylus. See Hazel
Cotyledons, 10, 218
Couroupita, 34
Crassula, 65
Crataegus, 26. See Thorn
Croton, 160
Cruciferae, 96, 193, 198, 204
Cucumber, 216
Cucurbitaceae, 193, 202, 214
Currant, 63, 92, 93, 166
Cycas, 159
Cyperaceae, 57
Cytisus, 81
Daisy, 198
Dandelion, 19, 198
Davidsonia, 92
Dentaria, 17
Desmodium, 214
Development of leaves, 46
Development of stipules, 46
Dianthus, 37
Dicotyledons, 64, 72
Diplophractum, 171
Dipsacus, 196
Disanthus, 160
Dock, 18, 61, 94
Dogwood, 90
Dormant buds, 17
Dorycnium, 202
Drimys, 40
Drosera, 63
Droseraceae, 193
Duroia, 191
Echium, 92
Elatine, 152
Elatostema, 187
Elder, 25, 26, 40, 92, 119, 203
Elm, 9, 10, 18, 27, 67, 69, 144,
224, 232
Ervum, 171
Euphorbiaceae, 34
Exochorda, 35, 38, 170
Fagus. See Beech
Fall of leaf, 228
Fern, 63
Ficus, 160
Flower-bud, 8
Fool's parsley, 200
Forms of stipules, 160
Forskohlea, 187
Fraxinus. See Ash
Galeopsis, 92
Galium, 59, 152, 184, 185, 207
Gardenia, 85
Genipa, 218
Genista, 17, 35, 82
Gentian, 73, 198
Geraniaceas, 34
Geranium, 34, 93
Geum, 167
Glandular hairs, 93
Gleditschia, 17, 231
[NDEX
237
Gloxinia, 18
Grarnineae, 215
Grasses, 57, 64, 216
Guaiacum, 25, 85, 160
Guelder rose, 67. See Viburnum
Gunnera, 195, 227
Guttiferae, 68
Gymnocladus, 10, 91
Gypsophila, 37
Hairs, 89
Hamamelideae, 122
Hawthorn. See Thorn
Hazel, 67, 92, 135, 160
Heartsease. See Pansy
Hedysarum, 31
Helianthemum, 20, 21, 34, 35,
36, 37, 184, 198, 202, 203
Helianthus, 92
Holly, 24, 26, 110, 161,184
Honeysuckle, 92
Hop, 32, 69, 84, 120, 152, 224
Hornbeam, 9, 10, 25, 26, 92, 134,
161,189
Horse Chestnut, 8, 10, 90, 91, 92,
93, 104, 108, 224, 230, 232
Hulthemia, 188
Humboldtia, 191
Humulus. See Hop
Hymenanthera, 23, 161, 184
Hypericum, 5, 72, 201
Ilex. See Holly
Ipomaea, 35
Iris, 64
Isertia, 219
Juglans. See Walnut
Kadsura, 40
Kalmia, 76
Knotweed, 31
Korthalsia, 192
Labiate, 92
Ladies' bedstraw, 182
Laminaria, 65
Lathyrus, 35, 54, 84, 160, 161,
175, 176, 177, 178, 179, 180,
183, 186, 198, 205, 218, 226
Laurel, 48
Lavender, 93
Leaf-base, 103
Leea, 120, 121, 160
LeguminosaB, 33, 34, 74, 91, 92,
193, 195, 202
Lettuce, 198
Ligule, 216
Lilac, 9, 10, 92, 94, 109, 223, 231
Lily, 57
Lime, 9, 10, 18, 25, 26, 67, 126,
189, 230
Linaceae, 193
Liriodendron, 50, 227. See Tulip
tree
Loasa, 92
Loaseas, 92
Lonicera, 92
Lotus, 201, 202
Lowea, 188
Lupin, 54
Lychnis, 37
Lycopsis, 92
Lythrarieae, 96, 193, 204
Mach^rium, 194
Magnolia, 29, 40, 102, 223, 225, 227
Magnoliaceas, 14. See Magnolia
Mahonia, 58, 60
Malpighia, 92
Malpighiaceae, 92
Malvaceae, 33
Maple, 8, 55, 63, 68, 73, 104, 198,
223
Medicago, 160
Melianthus, 57
Melilotus, 161
Melon, 214
Mesembryanthemum, 5, 6, 58, 63
Mimosa, 189
Mimoseae, 190
Mistletoe, 63, 65, 201
Monocotyledons, 7, 57, 64, 65,
215
Mucuna, 92
238
BUDS AND STIPULES
Mullein, 90
Mustard, 11
Myrtaceae, 34, 193
Nature of stipules, 197
Negundo, 73
Neottia, 19
Nettle, 92, 217
Nut. See Hazel
Nuttallia, 169
Oak, 10, 16, 17, 27, 68, 135, 1(50,
189, 223, 225, 230, 231
Ocrea, 60, 208
Onagrarieae, 54, 193
Onobrychis, 31
Orange, 190
Orchids, 19, 57
Ostruthium, 200
Oxalis, 67
Paliueus, 190, 192, 194, 226
Palms, 65, 67, 192
Pansy, 23, 28, 161, 184, 206
Paronychia, 160
Parsley, 199, 200
Parsnip, 199
Passiflora, 17, 35, 123, 160, 161
Passion flower. See Passiflora
Pea, 23, 28, 58, 64, 84, 120, 161,
179, 205, 217, 225
Peach, 22, 64
Pentapyxis, 42
Petteria, 28, 83, 84, 225
Philadelphus, 79, 80, 81
Picea, 157
Pinus, 153
Pisum. See Pea
Plane, 7, 61, 78, 79, 80, 90, 94,
95, 149, 208, 209, 224
Platanus. See Plane
Polycarpeae, 34
Polygonaceae, 88
Polygonum, 31, 61, 62, 89, 93, 94,
195, 196, 207, 208, 212, 217,
226, 227
Pomaceae, 82
Pomaria, 161
Pondweed, 31, 61, 62, 214
Poplar, 2, 18, 28, 92, 97, 124, 160,
224, 225, 230
Populus. See Poplar
Porlieria, 192
Portugal laurel, 22, 104
Potamogeton, 31, 61, 214
Potentilla, 54, 167, 168
Procris, 187
Protection of buds, 66
Prunus, 104
Psidium, 193
Psychotria, 218
Pterocarya, 91
Pterospermum, 161
Pyrus, 160. See Whitebeam
Quercus. See Oak
Quiina, 38
Quince, 166
Radish, 11
Raphanus. See Radish
Remijia, 191
Reseda, 57
Rhamneaa, 192
Rhamnus, 90
Rheum, 195. See Rhubarb
Rhubarb, 5, 71, 94
Rhus, 75
Ribes, 92, 166, 184, 190
Ricinus, 211
Robinia, 17, 26, 28, 29, 79, 80,
161, 189, 226
Rock rose, 20, 36, 45
Rondeletia, 219
Rosa. Sec Rose
Rosaceas, 33, 38, 57, 82, 170
Rose, 35, 52, 55, 57, 63, 64, 94,
103, 184, 188, 198, 217, 224
Rosemary, 63
Rubia, 185
Rubiaceaa, 33, 206, 218
Rubus, 217
Rumex, 61, 94, 195
Sainfoin, 31
St. John's wort, 5, 72
INDEX
239
Sagina, 37
Salix. See Willow
Salvadoraceae, 72, 189
Salvia, 92
Sambucus. See Elder
Sapindaceap, 34
Saponaria, 37
Saxifraga, 35, 65
Saxifrage®, 34, 92
Scotch fir, 153, 233
Sedge, 64
Sida, 217
Silene, 37
Silver fir, 233
Skimmia, 80
Smilax, 161, 192, 194, 202, 215,
226
Sophora, 74
Spanish chestnut. See Chestnut
Spartium, 81
Spergula, 33, 37, 73
Spergularia, 32, 33, 37, 73, 86, 89
Spermacoce, 219
Spiraea, 35, 45, 230
Spruce, 233
Stachys, 6, 91
Stellatae, 152, 185
Sterculiacea?, 171
Stipellte, 216
Stipules, 20
Structure of buds, 97
Sycamore, 105, 223
Syringa, 79, 92
Taberx.emoxtaxa, 95
Tamus, 203
Teasel, 196
Tetragonolobus, 201
Thalictrum, 195, 226
Thelygonum, 218
Thorn, 26, 161
Tilia. See Lime
Trifolium, 67, 173
Trigonella, 160
Tropasolum, 160, 193
Tulip tree, 2, 13, 50, 63
Tunica, 37
Tutsan, 201
Ulmus, 67, 144
Umbellifers, 73, 199
Urtica, 58, 92
Urticaceae, 187
Uvaria, 5, 70
Valeriana, 57
Vallea, 160
Verbascum, 90
Verbenaceee, 75
Vernation, 62
Vetch, 64, 174, 193
Viburnum, 10, 40, 41, 42, 43, 44,
45, 67, 90, 116, 204, 226
Vicia, 217
Vine, 84, 90, 121, 224, 225
Viola, 161, 195, 226. See Violet
Violaceffi, 206
Violet, 24, 63, 92, 94
Virgil ia, 91
Virginian creeper, 84, 121
Viscum, 65
Vitis. See Vine
Wallflower, 12
Walnut, 73, 90, 230, 231
Water lily, 63
Wayfaring tree, 90
Whitebeam, 67, 82, 97, 140
Willow, 2, 9, 10, 58, 97, 110, 124,
217 223
Wych'elm, 25, 26, 148
Xanthoxylon, 80
Yew, 233
Zajiia, 159
Zizyphus, 189
Zygophyllaceae, 192
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The International
Scientific Series.
Each Book complete in One Vol.
Crown 8vo. cloth, 5s., unless
otherwise described.
Edited by
F. LEGGE.
KEGAN PAUL, TRENCH, TRUBNER,
. . . AND CO., LTD. • .
DRYDEN HOUSE, GERRARD STREET, W.
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THE
INTERNATIONAL SCIENTIFIC SERIES.
Edited by F. LEGGE*
Each Book Complete in One Volume. Crown 8vo. cloth, 5s.
unless otherwise described.
I. FORMS of WATER: in Clouds and Rivers, Ioe and
Glaciers. By J. Tyndall, LL.D., P.R.S. With 25 Illustrations.
Twelfth Edition.
II. PHYSICS and POLITICS ; or, Thoughts on the Application
of the Principles of 'Natural Selection* and 'Inheritance' to Political
Society. By Walter Bagehot. Tenth Edition.
III. POODS. By Edward Smith, M.D., LL.B., F.R.S. With 156
. Illustrations. Tenth Edition.
IV. MIND and BODY: the Theories of their Relation. By
Alkxandrr Bain, LL.D. With Four Illustrations. Ninth Edition.
V. The STUDY of SOCIOLOGY. By Heebbbt Spencer.
Eighteenth Edition.
VI. The CONSERVATION of ENERGY. By Balfour Stewart,
M.A., LL.D., F.R.S. With 14 Illustrations. Eighth Edition.
VII. ANIMAL LOCOMOTION; or, Walking, Swimming, aud
Flying. By J. B. Pettigrkw, M.D.. F.R.S., &c. With 130 Illustrating.
Fourth Edition.
VIII. RESPONSIBILITY in MENTAL DISEASE. By Henry
Maudsley, M.D. Fifth Edition.
IX. The NEW CHEMISTRY. By Professor J. P. Cooke, of the
Harvard University. With 31 Illustrations. Eleventh Edition.
X. The SCIENCE of LAW. By Professor Sheldon A mo*.
Eighth Edition.
XI. ANIMAL MECHANISM : a Treatise on Terrestrial and Aerial
Locomotion. By Professor E. J. Marky. With 117 Illustrations. Fourth
Edition.
XII. The DOCTRINE of DESCENT and DARWINISM. By
Professor Oscar Schmidt (Strasburg University). With 26 Illustrations.
Eighth Edition.
XIII. The HISTORY of the CONFLICT between RELIGION
and SCIENCE. By J. W. Draper, M.D., LL.D. Twenty-second
Edition.
XIV. FUNGI : their Nature, Influences, Uses, &c. By M. C. Cooke,
M.A., LL.D. Edited by the I
Illustrations. Fifth Edition.
M.A., LL.D. Edited by the Rev. M. J. Berkeley, M.A., F.L.S. With
Edif
XV. The CHEMISTRY of LIGHT and PHOTOGRAPHY.
By Dr. Hermann Vogel. With 100 Illustrations. Sixth Edition.
Kegan Paul, Trench, Triibner, & Co., Ltd.
XVI. The LIFE and GEOWTH of LANGUAGE. By William
Dwkiiit Wiutnky. Sixth Edition.
XVII. MONEY and the MECHANISM, of EXCHANGE. By
W. Stani.ky Jkvonh, M.A., F.R.S. Eleventh Edition.
XVIII. The NATURE of LIGHT, with a General Account of
PHYSICAL OPTICS. By Dr. Euokne Lomkkl. With 188 Dlue-
trations and a Table of Spectra in Chromo-lithography. Sixth Edition.
XIX. ANIMAL PARASITES and MESSMATES. By Monsieur
Van Bknkdkn. With 83 Illustrations. Fourth Edition.
X
XX. FERMENTATION. By Professor Schutzknbkrqbr. With
28 Illustrations. Fourth Edition.
XXI. The FIVE SENSES of MAN. By Professor Bernstein
With 91 Illustrations. Seventh Edition.
XXII. The THEORY of SOUND in its RELATION to MUSIC,
By Professor Pietro Blaskkna. With numerous Illustrations. Sixth
Edition.
XXIII. STUDIES in SPECTRUM ANALYSIS. By J. Norman
Loceyer, F.R.S. With Six Photographic Illustrations of Spectra, and
numerous Engravings on Wood Fifth Edition. 6*. 6d.
XXIV. A HISTORY of the GROWTH of the STEAM ENGINE.
By Professor R. H. Thurston. With numerous Illustrations. Fifth
Edition.
XXV. EDUCATION as a SCIENCE. By Alexander Bain, LL.D.
Ninth Edition.
XXVI. The HUMAN SPECIES. By Professor A. db Quatkefacies,
Metnbre de 1'Institut. Fifth Edition.
XXVII. MODERN CHROMATICS. With Application to Art and
Industry. By Ogden N. Rood. Third Edition. With 130 original
Illustrations.
XXVIII. The CRAYFISH : an Introduction to the Study of Zoology.
By T. H. Huxlky, F.R.S, Sixth Edition. With 82 Illustrations.
XXIX. The BRAIN as an ORGAN of MIND. By H. Charlton
Bastian, M.D. Fourth Edition. With 184 Illustrations.
XXX. The ATOMIC THEORY. By Professor A. Wurtz. Trans-
lated by E. Cleminshaw, F.C.S. Seventh Edition.
XXXI. The NATURAL CONDITIONS of EXISTENCE as
they affect Animal Life. By Karl Skmper. Fifth Edition.
With 2 Maps and 106 Woodcuts.
XXXII. GENERAL PHYSIOLOGYof MUSCLES and NERVE8.
By Prof. J. Rosenthal. Fourth Edition. With 75 Illustrations.
XXXIII. SIGHT : an Exposition of the Principles of Monocular and
Binocular Vision. By Joseph Le Conte, LL.D. Third Edition. With
132 Illustrations.
^ XXXIV. ILLUSIONS: a Psychological Study. By Jamks Sully
Fourth Edition.
3
The International Scientific Series— continued.
XXXV. VOLCANOES : what they are and what they teach. By
John W. Judd, F.R.S. Fifth Edition. With 96 Illustrations.
XXXVI. SUICIDE : an Essay on Comparative Moral Statistics.
By Professor H. Morselli. Third Edition.
XXXVII. The DRAIN and its FUNCTIONS. By J. Luys,
Physician to the Hospice de la Salpetriere. With numerous Illus-
trations. Third Edition.
XXXVIII. MYTH and SCIENCE : an Essay. By Tito Viwnoli.
Fourth Edition.
XXXIX. The SUN. By C. A. Young, Ph.D., LL.D. Fifth Edition.
NWith numerous Illustrations.
XL. ANTS, BEES, and WASPS. A Record of Observations
on the Habits of the Social Hymenoptera. By Lord Avkbury.
Fourteenth Edition. With 5 Chromo-lithographic Plates.
: XLI. ANIMAL INTELLIGENCE. By George J. Romanks,
LL.D., F.R.S. Sixth Edition.
XLII. The CONCEPTS and THEORIES of MODERN
PHYSICS. By J. B. Stallo. Third Edition.
XLIII. DISEASES of MEMORY. An Essay in the Positive
Psychology. By Th. Ribot. Fourth Edition.
XLIV. MAN BEFORE METALS. By N. Joly, Correspondent
del'Institut de France. Fifth Edition. With 148 Illustrations.
XLV. The SCIENCE of POLITICS. By Prof. Sheldon
Amos. Third Edition.
XL VI. ELEMENTARY METEOROLOGY. By Robert H.
Scott. With 11 Plate* and 40 Figures in Text. Seventh Edition.
XLVII. The ORGANS of SPEECH. By Geobg Hermann
vox Meykh. With 47 Illustrations.
XL VIII. FALLACIES : a View of Logic from the Practical Side.
By Alfred Sidqwick. Second Edition.
XLIX. The ORIGIN of CULTIVATED PLANTS. By
Auhoxse De Candolle. Second Edition.
L. JELLY FISH, STAR FISH, and SEA URCHINS.
Being a Research on Primitive Nervous Systems. By G. J. Romanes,
LL.D., F.R.S. Seond Edition.
LI. The COMMON SENSE of the EXACT SCIENCES.
By the late Wdaiam Kixgdon Clifford. Third Edition. With
100 Figures.
LII. PHYSICAL EXPRESSION : its Modes and Principles. By
Francis Warner, M.D., F.R.C.P. Second Edition. With 50 Illustrations.
LIII. ANTHROPOID APES. By Kobeet Haetmann. With
63 Illustrations. Second Edition.
LIV. The MAMMALIA in their RELATION to PRIMEVAL
TIMES. By Oscar ScHMmT. Second Edition. With 51 Woodcuts.
4
vn Paul, Trench, Trilbner, & Co., Ltd,
LV. COMPARATIVE LITERATURE. By II. Macaulay
-kit, LL.D.
LVI. EARTHQUAKES and other EARTH MOVEMENTS.
By Prof. John Mii.nk. With U Figures. Fourth Edition, revised.
LVII. MICROBES, FERMENTS, and MOULDS. By E. L.
TllOU—IIMT With 107 Illustrations. Third Edition.
LVIII. GEOGRAPHICAL and - GEOLOGICAL DISTRIBU-
TION of ANIMALS. By Prof. A. Hkilpkin. Second Edition.
LIX. "WEATHER: a Popular Exposition of the Nature of Weather
Changes from Day to Day. By the Hon. Ralph Abehcuomby. With
96 Figures. Fourth Edition.
1 LX. A.NIMAL MAGNETISM. By Alfred Binet and Charlbs
Fkhk. Fourth Edition.
LXI. MANUAL of BRITISH DISCOMYCETES, with descrip-
tions of all the Species of Fungi hitherto found in Britain Included in the
Family, and Illustrations of the Genera. By William Phillips, F.L.S.
Second Edition.
LXII. INTERNATIONAL LAW. With Materials for a Code of
International Law. By Professor Leone Levi.
LXIII. The GEOLOGICAL HISTORY of PLANTS. By Sir J.
William Dawson. With 80 Illustrations.
LXIV. The ORIGIN of FLORAL STRUCTURES THROUGH
INSECT and other AGENCIES. By Prof. G. Henslow.
Second Edition.
LXV. On the SENSES, INSTINCTS, and INTELLIGENCE
of ANIMALS, with special reference to INSECTS. By
Lord Avebuuy. With 118 Illustrations. Third Edition.
LXVI. The PRIMITIVE FAMILY in its ORIGIN and
DEVELOPMENT. By C. N. Stauckh. Second Edition.
LXVII. PHYSIOLOGY of BODILY EXERCISE. By Febnand
Lagrange, M.D. Second Edition.
I. XVIII. The COLOURS of ANIMALS: their Meaning and Use,
especially considered in the case of Insects. By E. B. Poulton. F.R.S.
With Chromolithographs Frontispiece and upwards of 60 Figures in Text,
Second Edition.
LXIX. INTRODUCTION to FRESH-WATER ALGJE. With
an Enumeration of all tlie British Species. By M. 0. Cooke, LL.D. With
13 Plates Illustrating all the Genera.
LXX. SOCIALISM: NEW and OLD. By William Graham,
M.A., Professor of Political Economy and Jurisprudence, Queen's College,
Belfast Scond Edition.
LXXL COLOUR-BLINDNESS and COLOUR-PERCEPTION.
By F. W. EnaiDOK Guekn, M.D. With 3 Coloured Plates.
The International Scientific Series —continued.
LXXII. MAN and the GLACIAL PERIOD. By G. F. Wright.
D.D. With 111 Illustrations and Maps. Second Edition.
LXXIII. HANDBOOK of GREEK and LATIN PALEO-
GRAPHY. By Sir E. Maunde Thompson, K.O.B. With Tables of
Alphabets and Facsimiles. Second Edition.
LXXIV. A HISTORY of CRUSTACEA : Recent Malacostraca.
By Thomas R. R. Stubbing, M.A. With 11) Plates and 32 Figures in
Text.
LXXV. The DISPERSAL of SHELLS: an Inquiry iuto the
means of Dispersal possessed by Fresh Water and Land BfoUnsoa. By
H. Wallis Kkw, F.Z.S. With Preface by A R. Wallace, F.R.S., and
Illustrations.
LXXVI. RACE and LANGUAGE. By Andre Lefevre, Professor
in the Anthropological School, Paris.
LXXVII. The ORIGIN of PLANT STRUCTURES by SELF-
ADAPTATION TO THE ENVIRONMENT. By Rev. G. Hkxslow,
M.A., F.L.S., F.U.S.,