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McGILL UNIVERSITY
PAPERS FROM THE DEPARTMENT or
Botany.
iDon
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No. 5. — Myelopteris Topekensis, n.sp.
>- > BY D.Pr^'PENHALLOVV.
With Plates II. and III.
[Reprinted from the Botanical Gazette, January, 1897, pp. 15-31]
Montreal, 1897.
MVKI.OITKKIS TOI'KKKNSIS, N. SI'.
A M'W CAKIIOSII'ICKOUS I'r.ANT.
I>. I'. I'K N II A I.I.OW,
(wrni I'l.ATKS II AM) III)
I)uKiN<i the past sixty years a luinibcr of plants, variously described uiuler the names of Mediillosa' ( 1.S32) . I'aliiiacitcs' (1845), Myeloxyloii^ ( iS4(j) , Sten/.tliaM 1S64 ),aiul Myelopteris' (1874), have been obtained from the Carboniferous of France, Germany and Great Britain, but, so far as I am .uvare, 110 representative of this group has been obtaineil heretofore from any locality in America.
Recently Professor C. S. I'rosser has sent to me three small specimens of flattened stems from the upper Carboniferous of Topeka, Kansas. These fragments are about 6"" long and lie in a matrix of calcite.^ One specimen represents the full width of the original structure and is 33""" broad. A second has the edges broken off, but a natural extension of the curva- tures of the sides shows the probable breailth to have been about 6'^'". Both of these specimens have been compressed into a flattened mass having a lenticular transverse section with a maximum thickness of 5""" and 8'""' respectively. A third specimen, flattened to an irregularly lenticular mass, represents thin layers of plant residue adherent to the sides of the matrix, and obviously but a small part of the original structure. The dimensions of breadth here given represent very nearly the
'Cotto : Die Deiulmlitlienin liivit'luiiig auf ilircii inneren Uaii. Dresden, 1832.
'Corda : Heitr. zur Flora der \'or\velt. 1 845.
'Hrongniart :'rab. des >,'en. de vdg. foss. Diet. Univ. d' Hist. nal.
* Goeppert : Die foss. Fil. der perm. Form.
5 Renault : Ktude du gen. de^.Myelopteris. Acad, dc Paris aa : — 1875. | no. 10. |
* 1 am much indel)ted to Dr. H. J. Harrington for detenninations of tlie mineral constituents of these fossils.
1897] IS
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<n.im«tfr tif Itu- Hiriii tiirr iir in original fnrni. Thr ^n MHr.il . ..|..i !•> iImI <>| Iikiwii I u.iI. Tlir siirl.M r sliows ik ( iisiuii.il iir< ,i«i u| lliiii ( n,il\' ni;i»l«r iniK li hrnkiii u|» iiiti» Miiall angular Iragiiitiils, Itiit It IS iliiillv « li.iiailfri/»'il by » HnnH-whal fiiuly sliialti! a|i|ifaraiUf iliu' Ik ri'imtval hI iIk ...iliral lavi-r, with n»iis(t|ii( nt ixpnsiiif III iln- iiiKlfilyiiij^ >liafi'l-i u| M'lfrt'iichvriia.
I'lu' tLiiisvi-rsi- scttinii III thi' iiiiir«' |»rrfcrllv |irfs(rv»il H|H'cmKii sliii\v> an iiiilir /niic i ,5""" tliii k. uliii li is (iiminiiniis (111 ,ill sidfs. Ci'nlial tn this ami thus Imiiiiii^' tin- axis of tin- original siriutiiii'. is .1 ili^tiii« tly ilaiktr ami smmwli.it im,ir l>c>ii»iis mass, r«»iilaiiiiii^. luii- aiiii tlinc. small irr(rj,Milarlv roiimlfd massis nl |iyrilf. l)'|i<iii Mil)Mi|iiirit mi(ros«ii|ii( al c'xamiiiatidii, llicsi.' zonal a|i|i('aiaii<t> wnr luiiml tn lir din' tu wi'll lirfiiH'tl (lirffri'iicrs ol striu tiiri-.
I 111' mil riisn)|iiial lUtails pifsctit iii.iiu li .ituics of iiiti rest ami, allliiuij;li the m-iifral i-ffi-cts of die av ami ( oinprissioii liavc iiiiii to complctfly (U-slioy tlu'^tiirral nlalioiis of |iiiits, ami in many I'ascs, also, to (U-stroy stnutiiral ditails, tlusr last imvc hccn preserved, in some instaiui's, in a n-markahly ptrfii t manm-r.
Tin; ii;NrKAi axis. 1 In- intiif ci-iitral portion of the stiiii presents a romplete absence of strmtiiial ditail. 'llie whole central area is occupied i)y a mass of dark colored male-ial so disposeil as to indicate its prol)al)le derivation from thin walled tissue, but much altered by tiecay and tlii' sul)se(|uent effects of extreme compression. Here and there, dark colored masses appear, possibly the residue of the mucilajfe ori^Miiallv present. Thiouirhout this rej,non lari^^e rounded o|)eninjfs a|)pear. and while some of these undoubtedly represent the displacement of pyrite, many, and probably all, represent the former locations of vascular bundles, in the dark color and structural character of this area, we find amjile reason for its evident separation from the cortical /.one, as ascertained upon microsco])ical examination. Outwardly, this area is limited by a somewhat well defined but narrow and irregular darker line, which is obviously composed of much compressed thin walled cells, but which, nevertheless, seems to sug)j[est a somewhat definite boundarv line between a
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I MIlM l|lll lit
|iri'sfrv<'i|
( lilltilllMMIS
ixin (»f the Mliat iimrr irrt;>j[iilarly "roscopical
he due t(i
of iiiti rest Nsion have rts, ami in liavi' Iji'i'ii ii;iiiiii-r.
I till' Slllll
riif wliolf iiatr "ial so hill walli'il •nt rlfccts t(I masses y idcsciit. pear, ami iccmeiU of icitioiis of laracttr of ition from ;uiiinatioti.
ll'fllK'tl l)llt
composed I'crthclfss, between a
central tiicilnlla in wliiih thin vvalli-il (iitiilatiKtilal tis<tiir |>rt'> <lomiii,it('s, ,tnil .1 soini'what ri^icl, or at least firiiur, out) r /om-.
I 111. M»KirA, No proper tortical struiiiir«' is rrprrsnitt d II! ihiHf spt'titmiis I he outer liiuitH of the ttiatioitn ar«; fhTiiK il \>\ more or Ichh liroki ii iIovvii slramlH of HcU'rciuliyina lelK, with surroiiiiilin)^' parcm liynia tissue, making; it i tear that a certain ,iiiioiiiit of struiture has tieeii ri iiio^ed ; ami thisairords witti wImI has .ilreadv lieiii noted in spii itiieiis of Myelopteris, that "tin- tissue layers outside the sclcreni hyma strands are very rait l\ prcservftl."' In tins ease the thin surface layers of coal .ilitMfiv ilest rilu'il are in .dl proliahilits to lie re^'anled as rt presenliiiL,' theitirtiial struiture, wlinh must li.ive lit in < hit fly or vvholK parent In iii.'itous in eharat-ter, ami of small radi.d vtilmne.
I'm si 1. I o|< I |( \| I \\ I K. The outer, lontllMloUs /one. i.n"""
thick as alreailv iltsi riheil, li.is iis maertist uph ilitlen nti,ition from the meilull.i explaim «l l»y the Iar|,(e ;ini<iUiil <if lihioiiH elements whitli it < ont,iins nuiuLf to tlu- pre-i n« t of these t lenients, ami tht pet uliar way in uhiih thi:y are tlistrihiitetl, thev have ser\ed not onlv to prolei:t one .iiiotlu r, Imt they have ,ilso ser\eil to prevent the tl'fti t ol i ttmprission trom f,illiiij,' with full force upon the interveiiinu fuinlanientai strut lure whit h in conse(|ue!ice, h,is often retained its strut tur;il ft-aiures in an exceptitin.illv perfect m.inner ( /ii^'.s. / .iml -»i.
1'ak1'".N( iiVM A. — The i^rouml tissue, tor the irreattr ; .irt, is much .ilteretl hv tiecav ami ctunpression, so that all structural features, especi.itlv in the central area, have been pretty com- pletely elimin.itetl. ( )ccasioiially. however, when prtitected hy earlier inl"iltralit)n and petrif.ictioii, tir by the resistiiiLT char.icter of the acct.!n|)anyin,i( ;^tramls of hard sclerenchym.i, this part of the structure has been preserved in a very be.iutiful manner iji\^s. I and .?). I''roin these areas it is possible to tlelermiiit; the fact that this tissue consists of very vari.ible. but chiefly liir-^e ami thin walled elements of such a character as to reminti me very forciblv of the fundamental structure in many t)f the lar^^cr ferns.
'Si)lm>l.:iul)acli: r(i>>. H'.t. lOJ.
i
li
HOiMXn.il I, </A/7A
hi«M 411*
l'li> iiiU'ri'i'lliil.ii sjMCCH onliiLirity mu*I \«illi in Hiich tiNNtit* tiru |ircNi'iil, Intt llit-u' It ID) t-viilciiti' III lilt- I'siHti-nt'f of l.u iiii.i- St i i him iuma. It l);iH Ih-cii hIiomii .ilitMilv that tln' siilf curtu.tl /t)iu' \% !.«;""" tlurk. Willuu Ihi-^ region tlu-n- arc iniiiii-roiiHuval or liiii^t'iiti.illy I'loii^atctl iHinilk'M i>f NtU'rciii'liyiiia, wliii'l) U»\\\ lon^: ttriiiitlH travi*r>tiii^; tlic stem luii^itiiilinallv lor ^'n-at ilKtaiui's <.//c>' /. •/. inul ./). I'Iuhi' straiuK, wlmli \ii\i' till* |ii-( (iliarly slriati-d a|i|ii-arai)('f to tlu' Mirlaci- ol tin- >t|ic( iiiuii wlti-rt'vrr cx|to>*rtl, .ir»' alwav* si'|»ar.itccl Iroiii oiU' aiiulhi i hv Hcvcral lai^f ,iiitl tiiiii \vallc«l |»iirciitliyma «i'lls {fi}^. i) uliirli iiri' Hccn to In- vory |tfrlicctly pnv^crvwil in ctrtain ari-as. ||ju Mi'lcrfniliviiiatoiis clciiu'iits arc always vfr\ tliick wallril in those strands uhiih lii' mxl the mrtix ( //^,^ >' ). t'»it luruini' nimh tliiiiiit'i w.illi'd toward tlu- (inter ol llu-siini wlure thes ollcn appear to III- in a forniative eoiidition. The strands an* Hcparatcd radially by rather wide areas ol (iindaniental tissue (//</'. j), Itul in conseipienee of the ^^i-neral and ^reat alteration in relative positions el'fi-eti d liv lompressiun, it is inipossililc to ditertnine their ori^Miial distrilmtioii. The radial dislnlitition ol these strands thron^h a rather wide /one woidd seem to indii .ite that they ntay ha\e luen developed in more or less well deliiietl con- eentric layers, a relation whieh is certainly implied liy their distriliiilitin within eertain areas (//(,^.'). HeNdnd a limit of
1.3 Iroiii the siirlace the development ol the strands a|ipears
to lie wholly arrested.
\'\^i riAU inMH IS. riu- vaseular bundles are not Ireipieiitly represented, siuie in uiust cases they have been removed by decay, or other causes, and their former positions are then markeil by the presence of rather broail, irre^nilarly rounded openinj^s of variable dimensions, which appear throuj^hout the transverse section ( y/X""-*. /. -'. -md ,,'). and particularly internal to the sclerenchyma /one. Occasionally the bundles are preserved in a very perfect manner, and exhibit all their essential structural features with tfreat clearness {y/^,^ /). The outermost uf the two bundles seen in //{,'". /, when much enlaru;eil (//i,'-. y). is found to consist of several broad scalariform ducts enclosed 011 two
I MM tut
llHHtif tire
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till' Hllll-
tlUTf AtK.'
renchyina,
iiially lor liH li ^ivc >»|H'i iiiifii Itillirr l)V /I uliitli
CJIH, I III
li ill tlioNC illir lllticll lu'\ ullcn Ht'paiati'il
(C- ■'I . 'it'l II relative (K-tiTinitu*
m| tlu'Hi' liratc that fllU'il ruii-
l>y I heir I limit III Is appears
■re(|iicntly uoveil l)y are then V riiundcd ,^hniit the nternal to |)reservtHl stnictiiral St ul the ), is I'oiiiul
li 1)11 two
• ■•»7 1
.U r A A r»/7/ A7.S / 1 »/'A A A \.S/M
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Hlili'H l>y tttws )ii lliick walleii I'lhruiiH elritHMIts, The phlucrii, rtither Hiiiall tii vuliinie, in hen.* iiituh hrnki ii ilowii. hut it it •titiiiiteii riiiiiiilly outwanl, while in the other hiittille { Jijf. th where it in rather mure perleetly prcHervcil, it •« situated radially iiuv.iri!. The prntuxvli Ml in luri' sicn as n iiTnu\> of siiialU r elt iiienis iiiiuli altered l»y n»iiipre""<i«in ( /f),'. /). or i»i otlnr iiisiiiiices mure perfectly preservi il (///;. /), sometimes un the uuter fuce uf the veNsels, {irid sumetiiiicH un the inner face, hut Hlways hetween them and the phloem. While the hundles vary con><ideral)lv in si/e, tin v all < unlnrm to the en" iteral type and it IS ol interest to note ili.it in .ill their structur.il features, they H^:ree very cli»scly with the iKindlcii of n Hpeclen of Myclox\loi) tltserilied l»y Solnis |,.uil).ich," and xhtt hy Seward.^
l*'rom the present material I have heeii wholly un.ihie to oliiiiin ^atisf.utorv det.iiN of th«' structure (»l the bundle m loii^'itiuliii.il section, he;, Olid the latt that the vessels are dis tiiu tlv scalarifornt, and in this respect they conform to the type j^eiierally ohservi d in (mis.
The peculiar situation td these bundles is not altoj^ether easy to .lecount for. Tlu \ icrtainlv appe.ir to lie between, ;ind are therefore iiiitifrliil Willi, the strands of si K reiichynia, from which eircumstiinee I was at first led to siippos*- them to he collateral, as in the case of I'hoeiii\ .iiid titlier p.iliiis, but .t very careful examination fails to disclose any satisfactory eviilence of such relationship, while in some cases at least the vascul.ir bundle is separ.ited from the nearest sclerenchyma stranil by a broad zciie ni fundamental tissue. Indeed, the evidence, so far as obtain- able from the present material, seems icj indicite that these bundles and the sclerenchyma are altot,'ether independent of or\c another; but in the present unsatisfactory comlition of the niateri.^I now available, :io fin.il conclusion can be drawn. Kroiii the eviilence at hand, however, it would seem that the vascular bundles have their extreme outwanl distribution in the central portion of the .sclerenchyma zone. I-'mm this position they
•^■o^!^. It'll. ii>i. //f. / / /i,
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( I A M \ K V
ilUllMSi- ill IIIIHlhlT illUMld tin- 1 I'lltlT .111(1 1)C( lilllr llll>->t iiuiiu'r-
oiis uilliin tlu' ci'iitiii' rii^JDii.
Si cKi.TiiKv oK.iAN.-.. A ii()t,il)U- fi-at'irr ^li llu" prcsfiil fossil is tlir orciirronci- of mmuTous largi. iiiiicila^f passa^fs. As a nik' tln'SL- stniiluifs ait' imuli altiTiM hv ili-iay ami c-nmpiis- sioii, hilt ill two instances tlu'V wire foiiiul in a vi^y piTfi'Ct state ol preservation ( //;,'-. J\. So far as it is at pii'scii possible to deteriniiK', these organs occur tlirounliuut the siih-cortical region where thev are in nion- or less intimate association with the sclerencliyni.\ stran('s. i-Jsewhere it is not possible 1o determine the (listrihiition satisfactorily, l)nt, fiom our kii iwledi^c ol their occurrence in recent |<laiils, it is a fair inference tliat they must also be distributeil throui'li Die entire l)ody of the fniidaiiuntal structure.
Measurements of such of these passages as were in a sufficient state of prcservati.m for such a pu'pose showed them to ha\e the lollowinn' dimensions: i.;;xi00jw,; JC);xi3;/x; 2 1 1; ■ 143^. From these results it is possible to deduce an averaj^e dimension of 127 I(j2/x. I-'-om this ayain it appears that these passa<.jes mavbe described as of elliptical form, in which the minor and major axes have a ratio ol i : 1.5. The very great size of these structures, unusual except in a few irroui)s of plants, seems to su'^^'nest a comparison with both Lyciclaceie and Marattiace;e. In structure they are siniijle. LoiiL,n'tudinally thev form liMig tubular passaf^es which traverse the stem for great distances. l:i transverse section they consist of large ellip- tical openings bounded by a very regular w.iU composed of par- en:hyma cells often iliffering but little from those of the sur- rounding tissue. Thev are mc>re commonly somewhat elongated tangential Iv to the central canal, and by analogy with similar structures in recent plar.ts we may infer that they contained active proto])lasm. Thev thus forn: the secretory cells, or an epithelium which is not .-.pecially differentiated ^fig. _^). A comparison of the two canals {fig. 2) will serve to show, how- ever, that the secretory cells often show little or ikj dexiation from llie general character of tlie fundamental structure.
( I \ M \ H V st IIUIIUT-
HMit fossil
t"-. As ;i
cumprcs-
\- [HTli'Ct
iussil)|i' to cal rr'^ioii I witli tlu' (Iftfiiniru' (• ol tlicir tlicv must idaiiu'iilal
icrc in a wed tlitin D5X i3;/x; IcdiKc an it a|)|)(.-ais 1, in whicli
The \rrv groups ol l.iCLM' and ;itudinallv
stem for art^c el lip • ed of par- )f the sur- eloiigatcd itli similar contain. -d A\s, or an
:^- /)■ A
how, how- dexiation structure.
iK>7|
MVi.i.ori hRis hiI'I-.k i:\sis
31
Another important feat'ire of tliese laiials is t«. Ix- found in the fact that tliev are always devoid of contents. llii-. ap|)ears to justily tlie view tliat wliatever they may liave contained origi- nallv was of a soiul)ie nature and thus |)assed out ol the ixuly of tin- plant during the process of petrilactioii.
In all tlieir principal structural aspects these canals hear a stronj,' reseml)lance to those of Ani^iof^fcris ivcctii (they are of the same tyi)e), and it mav al^o l)e |)ointed out that they are similar to tliose fourd in Riuliiophris / 1 '////</w,sw/// vvhi( h .Seward has recently separated honi M velowlon," as also to tiiose of Myeloxylon itself."
'rhroutfhoul the transverse section of the Topeka specinuii there are numerous resinous or coaly masses of very variable si/.e, l)Ut cvidentlv originalls contained in special channels or cells, which have heconu' much disorifani/ed, aiul the details ol which cannot now he made out. In huinituilinal section these masses are (;f indefinite lenjfth. but ratiier freiiuently septate. From these features it is |)ossil>le to refer them to the residue ol resin masses which the plant oriifinally contained, and they are, therefr)re, directlv c(jmparaljle with the similar resin bodiis fouiul in recent plants, particularly those of Ani^iopkns tVCiUi.
It is tiui^- fairlv certain tiiat in the Topeka plant there were orii(inally at least two. and possibly niore, kinds of secretory origans, tiie one holding mucilage, the other resinous matter, and in these resjiects our plant is once more comparable with certain recent forms.
The general view of tiie internal structure thus obtained permits us to gain some conception of the real composition of this stem or stipe, from which we may infer that a restoration would show a cortical layer of parenchyma at least several layers of cells thick, containing numerous mucilage passages. P'ollow- ing this is a sub-cortical zone distinguished by the presence of nuiiicrous rather widclv separatetl strands of sclcrenchyma, the elements of which are very thick walled toward the cortex, but
■'.\nn. Hot. 8: />/. .V///./(V.f. 'i' // t.'"- " .\nn. Uui. 7; //. I, figs. 1,1).
-r*jSJ^^^^|J(^||flffff^^BnW^?J^''"'
HO/AXJCl/. UA/./.J //:
I.IANIARY
Cdiuimially tliiiitu"' walled toward the mciliilla. Tlicsc strands iisuall)' liavf an accompunvin^ iiuicilajfc passaj^c on the oiiter lace, inul are inconstant {':) process of formation tow.ird tlie center. Within this zone, vascular bundles, distinf^uislied by tiieir broad scalariform vessels, appear, anil increase in number toward the central re^non. The central axis consists of a rather broad tract of parenchyma tissue, throuj^h which tlie vascular bu.ndles are distributed in larj, numbers.
l*rom this point of view, and with ilue allowance for the effects of compression, it is possible to trace a strikinj^ similarity in several respects to a species of Myeloxvlon describeil by Solms-Laubach," and i lore |)articularly in certain respects to specimens of Myelopte is described bv Williamson.'^ The evi- dence is both clear and direct that this plant must be considered as belontrinn' to that peculiar trroup for which the name Myelo|)teris, pro])osed by Renault, has been most jrcnerally emploved.
In 1S32, Cotta ilescribed certain fossils from the Carbonifer- ous of Kuro|)e under the name of Medullosa, which has more recently become mer^red in that of Myelopteris. Williamson, however, informs us that Cotta's figures of M. clegans are wholly misleading, the structure being represented in a much exagger- ated form, while his two .>^pecies, J/, stiilata and .]/. porosa, remain too obscure to be depended upon without further evi- dence than has come down to us.'^ The genus Medullosa, nevertheless, constitutes the basis of that group of i)lants which, ])assing under several names, ha;; finallv come to be known under that of Mvelopteris.
In 1845, Corda assigned to his genus Falmacites two plants from the Coal Measures of Bohemia, under the names of P. ntrboiiigciiiis ami P. Icptoxylon.^^ An examination of Corda's figures shows that there is no very great resemblance, although
"Fos.s. Hdt. l6i, fiji. 14A.
■'Fossi, plants of tlic Coal Measures. I'hil. Trans. 166: fin!. /,.?, 4. '■•Koss. plants of the Coal Measures. I'hil. Trans. 166'. 'SFIora tier Vcjrweit 4c, 41. //. /9, .?(). 1845,
I.IAMARY
c Strands the outer •ward the lislicd bv II iuinil)cr if a rather
■ vascular
L' for the simihirity :ribecl l)y rspects to The evi- onsitlcred he name j^cne rally
irbonifer- lias more illiamson, re wholly exagger- '/. poros(7, rther cvi- IcduUosa, )f plants be known
\\o ])lants lies of P.
■ Corda's although
lSi>7
M) / lor/ / h/S /<)/7A/:XS/S
M
there is a suggestion of similarity to our plant in the general eiiaracter of the fundamental tissue, and tiie presence of numer- ous mucilage passages. These latter, however, are small and a|)|iarentlv altogether separated from the vascular bundle.s.
Subsecpient observers have not been unmimlful of certain structural aspects in these plants, which ha\e seemed to suggest their possii)le relationship to the palms, and more particularly to that tvpe of structure represented in the genus IJrac;ena, but much doubt has always been entertaineil as to the possibility of mono- cotyledons occurring so far back as the Carboniferous. These doubts w-ere first ijromiuently expressed by lirongniart as the result of comparing with the plants figuied by Cotta and Corda, new material obtained from Autun, France."' He says "il y ait des differences fort essentielles et (|ue rendent tres difficile d'etablir des rapports entre ces fossiles et les vegetaux vivants." He therefore preferred to regard Cotta's Midullo.ui i/t\!^'-a//s as the representative of a new genus, for which he proposed the name Mveloxylon. which thus seemed to indicate the leading structural features indicated by the former name, the signifi- cance of which was thereby jjcrpetuated.
Fifteen years later, Goeppert, in reviewing Cotta's species, regartled Midiil/osa cligtiiis as possessing characters which were variously represented in the gymnosperms, in i)alms, and in the ferns. As a generalized type, he applied to it the name of .Stenzelia.
In 1873, Williamson first drew attention to the belief that the relations of these fossils had not been correctly interjireted, and expressed the view that tiiey were really ferns allied to the Marattiace;e.''
In 1874. Renault reviewed the fossils obtained from the Carboniferous beds at Autun, as a result of which he supports the conclusions reached by Williamson, and while he regards the name proposed by Corda to be wholly untenable, and those of Cotta and Goeppert to be insufificiently indicative, he views that
"'Tab. des gen. ile Veg. l-'oss. Oo. 1849. (Quoted from Williamxm.) "Hril. A.-is. .\<X\. Sci. 1873.
I
34
/U)/.l\/l'.t/. (,.l/./:/r/:
I ia.\i;akv
of Hroii^Mjiart \vit!i lavor, l»iil ictfards a tlinVrcnt form as more- expressive of tlie rclati()nslii|) wliicli lie (litirniliud.'** He tluit lore says: " I'oiir coiiserver le iioiii, |ireiiiier eii tiale, doiiiie |iar M. Hron^niiart a ces [jortioiis de plaiUes, et eii iiieine temps |toiir rappeler leiir nature, je les desi^iierai sous !e iiom tie M yeloptcris."
riie yet more recent studies of tliese plants h\ Williamson led him to admit the force of the ari^uments employed Uy Renault and the appropriateness of his nanie.'^ Referenct- to Willianisou's figures discloses several points of resemblance between his specimens and my own. This is to be noted (irsl in a i,n-eat similarity with res|)ect to the Lfeneral distribution of tissues, particuhiily as exhibited in his Jii^s. j and ./, as likewise in the very general removal of the vascular inmdles. The vas- cular bundle i,nven by him ( Williamson, y/^'-. 7*) is closely similar to that derived from the Topeka s|)ecinien [ Jii^. 7), but differs materially from his other representation (Williamson, y/i,''- 7) taki'U from the uj)|)er end of a rachis, which is closelv simil.ir to bundles observed by me in Dioon cdulc, whereby it offers some basis of C(jmparison with the Cvcadacea;.
In longitudinal section the resemblance is rather close, but in this aspect the To|)eka specimen offers little evidence of a satisfactory nature beyond the general relations of jiarts, anil the structural markings of the vessels winch are seen to be scalariform, as in the ferns.
Finally, the relation of the mucilage passages to the vas- cular bundles (Williamson, y?^. 14) and of the very large, elli])- tical mucilage passages to the sclerenchvma strands (William- son, Aa''- A))> ^^ '^'^" i''*-' ^■'-"'■y thin walled elements of the funda- mental structure, all |)resent features almost identical with those observed in the Topeka specimens {Jigs. /, ^, .?).
Williamson's specimens appear to differ from mv own chiefly with respect to the particular distribution of the sclerenchvma strands in the cortical region, a difference which, however, is
■' Reclierclies .sur les veKctaiix silicitics d'.Viitun. ( l-'rom Willjumxtn.) " Fos.sil plants of the Coal .Measures. I'liil. Trans. i66'.
I i\\i;akv
II as more ncl/" ifc late, (Idiiiu'" einc temps L' iKim <lc
A'illiamsnn ployed by ■tereiice to ;scnil)Iaiice noted first iil)iiti(iii of as likewise The vas- ^ely similar but dil'lers
t^'i.A'-- 7) • similar to
Ifers some
■ close, but
deuce of a
parts, and
ieeti to be
o the vas- arife, ellip- (Williani- the funda- with those
)vvn chiefly ereiichvma lowever, is
n.)
IM.,7
.M\ I i.oi'i r.ias i{<i'i Kissis
35
more speeilk: than y;eneric, l)iit my material has been so altered bv compression tliat I slimdd liesitate t<t place much reliance upon tliese aspects oi >triuture, preferring- ratiur to establish the aflinity i)y nicans of the more perfectly prestrved slriutmal elements.
The distribution of the vascular l)imdles in concentric zones, as described by Williamson, may also be a feature of the Topeka specimen, but for reasons alreaily stated this cannot lie asserted with anv def^ree of confidence.
More recently Solms-I.aubach* has reviewed the entire relations of this tfrouj) of i)lants, and while lie rejects Renault's name because he rei^ards the evidence as not altogether satis- factory, he prefers to retain HronLjni.irt's name (jf Myeloxylon ••rather than .Sten/elia, because it is better known." He \(\\c^ two il^nires, one of a i,a-neral transverse section, the other of a separate vascular bundle, and it is r)f considerable interest to note that this latter is almost the e.\act counterpart of a vascular bundle obtained from the Topeka fossil (y/!,^ /i. His ^a-neral vii-w of tlie structure is not so satisfactory, but it nevertheless exhibits a close similarity to my own material in all its principal features.
Solnis-Laul)ach dissents from the conclusions of both Renault and Williamson, holdini( that there are stront^ reasons, on ana- tomical trrounds. for considerin^r the alliance to be with the CN-cadace;e, and cites Mcdnllosa Lciulun-ti as pnjbably affording important evidence in support of this view.
The most recent contribution to our knowledL^e of these |)lants is that offered i)y Mr. A. C. Seward, who has not only reviewed tlie material originally described by Williamson, but has made a detaileil study of specimens contained in the Hinncy collection of the Woodwardian Museum. Cambrid;^^'. as well as of new naterial derived from the Millstone grit of Lancaster." The o.'r, ^.')ses show that his material is generically the same as tiiat represented by the Topeka specimens as described. In a
^'Koss. lii)t. 161. I^'OI. =" Ann. liot. 7:1.
It
a6
MO TAX/C.t I. GA/.E TTE
[jANi-A«V
scCDiid |);i|)cr, tlic same authority tuakcs a stiulv of certain spec- imens containetl in the Williamson collection and originally incliulcd by Williamson in the ^rcniis Myelopteris, hut which he fiiuls to be in reality ([uite distinct. lie therefore He|)arateH them under the name of Riuhhptcris WiUinnisoni." This species is quite tlistinct from our Topeka specimen with res|)ect to the character of '.he vascular bundles, which are concentric, and thus show a tlistinct approach to the type represented iit Aui:;iof>tins evccta. On the other hand, the mucilage passages, which are also of the type found in Angiopteris, are essentially the same as those of the Topeka specimen, differing only in distri- bution.'3
l'>om the review thus presented, it is tpiitc clear that our specimen must be regarded as a s|)ecies of myelopteris, accord- ing to the name adopted by Renault anil Williamson, and retained by me as expressing its probable relations, but that it differs s|)ecifically from any of the specimens heretofore described. It may be concluded further that the present mate- rial represents the stipe of a frond, rather than the stem proper.
Heretofore the representatives of this genus have been derived wholly from the Carboniferous of Kuropc. The material now at hand from the Upper Carboniferous of Kansas thus afforils important evidence as to the wider geographical range of these plants, while the well ])reserved condition of portions t)f its structure permits a further discussion of its possible affin- ities. I have, therefore, carefully passed in review such species of living plants as are available in the botanic (iardens of McGill University, as affording a possible solution of this ques- tion. In jjrosecuting these studie;N I have had in view the sug- gestions of earlier investigators, as well as those which natu- rally arose in my own mind upon making a preliminary examination of these fossils. I have, therefore, carefully exam- ined Cordylinc tcrminalis. Phoenix dactylifcra , Kcntin Fosteruvia,
=-■ Anil. Hot. 8 : 207. -■'.■\nn. Bot. 8://. /.^A^ *.
f lAMAKV
•rtain spoc-
orijfinally
t which he
; SL-paratcs
his spt'cit's
)ect to the
c.and thus
/hii^io/ifin's
wliiclj are
the same
in tlistri-
r that our is, accord- uson, and )iit tliat it heretofore scnt niate- tlie stem
have been ic material msas thus ical ranjj^e if portions sible aflfin- ch species ardens of this ques- w the sug- hich natu- reliminary Lilly exani- Fosteriano,
I8.J7I
MM. I A tpTKKts ror/:Ki:\s/s
>1
LiitiNiiii borbonha, Cyciis irroliitii, IHoon cdulc, /.lonio intn^ri/oliti, Cibotiiiin tr^iih, and .■hij;^io/'/iii.\ ivcitii.
A close comparison of the Uracicna type, as represented by Cordvline, shows that any suj,fgeslion of resemblance which might at first appear, has no real basis in structural characters, while in manv essential respects there is a \ery wide difference. Noteworthy points of reseniblance being absent, it is wholly uiujecessarv to enter into a more iletailed consideration of the structural aspects of this type. \'ery nearly the same observa- tions arc applicable to the palms. In this grou|> of |)lants, how- ever, there is a somewhat closer point of contact to be found in the mucilage passages. Here these structures appear as tubular channels of great length, and in this respect, as well as in their distribution and great number, there is a general resemblance to the Topeka fossil. Their detailed structure is, on the other hand, (|uite different, anil it jxiints to a want of aflinity which is sup- ported bv the structure and distribution of the vascular bundles, as also the character of the funilamental structure, and no very searching comparison is required to establish the fact that the affinities of our fossil must be sought elsewhere.
Hv several authorities the Cycadace;e ha\e been suggested as affording a satisfactorv basis of comparison, a view which, in more recent times, appears to have been particularly urged by Solms-Laubach,^* although he elsewhere agrees with other observers that certain exceptions which have been taken to the cycadaceous character of the Medullos;e are well fouiuled."
Mr. Seward, vet more recentlv. has given expression to the same view, basing his opinion upon a very critical examination of a large amount of material.-''^ While admitting the many points of resemblance to ferns, he holds that in the position of the protoxvlem and in the structure of the fnucilage passages, as also in the distribution of the sub-cortical sclerenchyma, there arc strong reasons for considering the affinity to be with
^*l-'<)ss. Hot. Ibl. 'ilMii. 100. "'^Aiin. Hot. 7: iS.
!
«l
*.
fi
in
I
i
.1
I!
.'S
/mr.iMc.if. i;.\/.i- 1 II:
(lAMAHV
tin- cyi.uls ratlur than with thi- firns. Without liopiii^- to settle this i|iicsti<tn at ihf prcsiiit tiim-, it may l)r prufitalilr to coiisiilcr .some of the arguments ailvancctl by Mr. Seward in the light of tvideiice obtained froii) an examination of material ilerivcd from existing species, as also from the Topeka specimen itself.
Vasili.ak iiiM)i.i;s. — An examination of both tyeadaceoiis jilants and ////i,w/'/<m cvccto afforiis but littU- evidence contrary I') the view urgeil bv Mr. .Seward. The evidence obtained shows, as he contemls, that the position of the |)rotoxylem in these plants is certainlv an argimieiit in favor of the cycadaceous character of .Mveloxylon. On the other hand, the collateral character of the vascular bundles in the latter cannot be taken as final evidence of afViiiity either with the ferns or with the cvcads, as Mr. Seward himself points out. Althougli the longi- tudinal sections of the Topeka specimens havi' given far from satisfactorv results, the evidence to be derived from them indi- cates a much closer resemblance to Angiopteris than to any t)f the cvcads 1 li.ive been able to study.
.Si;( KKiuKV ()i<(;.\Ns. — lu the Cycadacea', ;is represented by Cyciis nvoliitii, /.oniui iiili'i^rifolid, and Dioon ciiiile, the secretory organs ap|)ear to be all of j>ne kind as represented by mucilage canals. These structures are distributicl throughout the funda- mental tissue and are represented by broad canals v/hich are chiefly limited by tangentially elongatetl parenchyma cells. These latter, therefore, differ somewhat conspicuously from the cells of the surrounding tissue, as already shown by Mr. .Sew- ard.'' .So far as apj)ears from the species above irulicated, how- e^'cr, these canals are alway.s lined with a layer of very thin- walled epithelium cells, which become ru|)tured with age and, shrinking back upon the main wall of the canal, give it a thick- ened and very ragged ajjpearance.
In Angiopteris cvecta there are three distinct kinds of secre- tory organs: {a) tannin sacs, \,b) resin canals, and U) mucilage canals.
=?Ann. l{<it. 8: 214.
1 i
I I A M \ K V
liopiim to (ifitalili' III Seward in il iD.'itfrinl
I sprciilun
■ciulfiiruiis ;c contrary ncd allows,
II in these ,'ca(laccoiis
coilatLial )t be taken ir \vitl\ the
tliu longi- •II far from tliein inili- II to any of
cscnttil l)v ; secrctorv y nuicilaife the funda-
which are yma cells. V from tlic y IMr. Sew- atcd, how- very thiii- 1 age and,
it a thick-
s of sccrc- ) mucilage
|H.)7|
.1/ ) A l.Ont-./i/S Ton. A7. .\.s7.s
29
Toniiin stus. Ill U-iiisverM- section the tamiin sarn .ire ultrii harely ilistiiigiii^hahle frtnii the resin canals, In reason of their structural similarity. They occur al>un<lantly in the cortex and ^l^roll^dlout the fundamental tissue, and especially in ilose |»r«).\- imity to or within the limits of the vascular hundles. To me these appear to he the structures rcfcrieil to by Mr. Seward in his description of Kmhiopkns W'illiiiinsoni, when he says, "there are smaller canals in the peripheral part of the phloem of each bundle."'** In longitudinal section tliesc sacs are seen to be of about the same diamet<'r as in the transverse section. e.Ncept in the cortex, where thev assume the loMii of cylindrical cells about three or four limes longer than broad. The contents are much lighter colored than those of tlu- resin canals, and often present a well defined granular appearance. They readily yield the characteristic reactions for tannin,
Rfsin <v///^//.v. — Throughout the sub-corticd zone, scattered among the sclereiichyma cells ami also central t«) each of the isolated strands, are rather broad canals of indefinite length. Throughout the fundamental tissue, particularly in the neighbor- hood of the vascular bundles, there are also numerous c ;iii.ils which differ but slightly in their structural aspects from the surrounding cells. In all cases, however, they are at once recognizable by the r.ither ilark reil resinous mass which each contains. In longitudinal section the canals ;ire of indefinite length. The contents are often septate. These structures appear tt) mc to be comparable with the black, resinwus m.isses of variable size to be met with not only in the Topeka specimen, but in most of the Kuro|)ean specimens of Myeloxylon.
Miiciltigv Kimtls. — Throughout the ground tissue of Angio- pteris there may be seen broad openings bounded by more or less taiigeiitially elongated cells. These are the canals from which issue the very large volume of mucilage freely liberated when the stipe is sectioned. These canals are always limited by cells which differ but little from those of the surrounding tissue, except that they are more or less elongated taiigentially. Here
•-•'Ann. Hot. 8: 214.
fl
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I
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r I
I*
M
m>t'i\n u I, i/h lit
\\SHV\*H
llun* in no «<|»»cl;illv iliff«niiliattil t|iithiliiim, ;int! in tlii«« rtN|ntt w.' unit will) a Icitiiii' wliitli sirv«s tn sIi.m|iIv M|iai.ili- tlus«' .stiiiitmi's Iroin Uiuhi- hI tin- l.yiatlai «',r. < >ii llir^f uniiimh I mIiouIiI ti'il m» hositalioii iii ^l^•t•i(lill^; as tn wlnllitr a ^;iviii plant wi'rc cvi"iulai"iM)iiH m filimiil iti its alVinitits. l-'inm llii', |miiiiI ul vifW, tlu-n, It \\i>ultl sitin that tlir lt>|i«'ka s|iii iimii in inun- lu-arlv alli«'<l to Iitiih. and tin* same wniild Imlil (riu- ul Myrlu.s- vliin. il \vr an- tn haso an i>|iinii>n ii|Min tlir i'.\«illrnl li,niin-> u\ Mr. Si'waitl.
Sin-i iiKin \i SI iiiKi'MiiVMA, — Tlu' ilistrilKilioii <>t tin- sclri- i'lu-hyma lan liaidly l>o taki-ii as an arj,Minu-nt uiu- way m tin- ..till r. siiui- lii luilli liTiis and cyfails tln-ir is siuli widf variation. I .should cons'clcr this a sprcilii latluT than a i-fniiu' i liar ictrr. In all of tiu' njycloxylons so lar studiid. tlu' m lirfiu hyiii.i is dislributi'd in st-paratc strands. In the i)iads studinl l>\ inc this tissue forms a continuous i)and in all lasi-s wht-rr slrnn^ly di'\clo|n"d. In .\n>jio|itiTis it forms a rontiniions /oiu' of ron- sidcrahli.' lliickiu'ss, with si'|>aralc stramls lyin^^ aloii^f tin.- iiiiur
face.
A rcsunu' i>f the results above- dctailo<i shows that in tin- To|>i.'l<a s|ii'cinicn tluMV arc characters which directly connect it with Kitiliioptcrii Willi, nnsoni, and aUo with other l-airopean spe- cies of Mvelo.\ylon, and tlu- ividence would seem to indiiate that few of these can be separateil ifeiierically. yUlmittinu the force of sonii- of the objections raised by Mr. Sewaid respecting' the tilicoid character of Myeloxylon, there are, nevertheless, Strom,' arguments in favor of this \iew. which seem to me to jire- poiulerate and thus to justify the retention of the name Myelop- teris as a name expressive of this possible relationship; while the fact that these plants do not conform closely It) any modern tvpe would seem to raise a ipiestion as to the possible correctness of the view oriifinally expressed by (ioeppert that these plants in realitv represent a ^Generalized type occupyini;- a position between the cyads and the ferns.
llolASK Al. I.AIIORAIOKV,
Ml Gil I. 1'MVl.R-iirV, M'lMKKAI..
1 1 >sr \H\
{ivcii |il.iiit MH |)niiit iif 11 i> mure il Myil.ix-
I rinuifjt of
I till- «.i;lfr- vv.iy or \]u' I- variation. rhaiatt«T. luliyiii.i is liid l)\ MM- rr sliniij^^ly
ilJf ol 11)11-
f tin.' iiiiur
that in the • coiiru'ct it ■o|)t'an s|)c- to indiratc [iiittin,^: the
respecting jvcrthelfss,
nio to |)rc- iie Mvelo|)- sliip ; while my inotleni correctness hese plants
a |>usition
•>"•■; I
l/l / /('/■// A/s .'0/7 A / \Sl% I Ml \S \ I InS Ml ri.A II n Wh III
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cf yn It
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III, • I i,iii«vrt-«i' •»<•' Mull -iMm III.' Ill' «i iiit II' liv iii.i -li.iiiil-, Willi l»»" l;(ii.'f mm il4iK<' |'iii«MK»» • (X
I I \ I I Ml
III,, ( ri,iii»vt|i(r Ml linn "I .1 HI IciriM li\ MM -ll.ili'l 'tiumh" <li liiiN <if tliih til II' III II tiiil' iliiu'i' iia-**:!!.'!' I'll il-" iiilli I liii I'. ■ t-'i
III,. 1 I t.lll'^M'tHC vcill.Ml III .1 V.f.ll|l,(» llllll'llc 'll'lWItlL' 'UirtiN •>!
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MVKLOi'lKKlS I'ori'.KKNSIS I'enliallow.
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