PALMOXYLON ARCOTENSE SP. NOV., A FOSSIL PALM RESEMBLING THE LIVING GENUS LIVISTONA, FROM SOUTH INDIA

C. G. K. RAMANU]AM Birbal Sahni Institute of Palaeobotany, Lucknow

INTRODUCTION parenchyma are to be seen. Purely fibrous bundles are completely lacking. The auri­ HE species described here is repre­ cular lobes are generally round. The fibro­ sented by two blocks of silicified vascular bundles on an average number 110 T woods. It was collected from near 2 per cm. . The ground parenchyma consists a village Tiruchhitambalam (PL. 1, FIG. 1 ) of rather compactly placed thin-walled oval in South Arcot district about 8 miles WNW to rectangular cells. Leaf traces are not seen. of Pondicherry. But for Sahni's (1931) Subdermal Zone - The fibro-vascular bun­ short description of a new species of palm, dles again regularly orientated are com­ Palmoxylon Pondicherriense, there is no other paratively sparser being 50 to 65 per cm. 2, published record of fossil palms from South and are generally obovate to orbicular, India and up till now only the famous Deccan although oval shape is not uncommon ( PL. 3, Intertraps have yielded the rich collection FIGS. 9, 12). The bundles are about 175 [J. of palms from Indian horizons (two species and the F IV ratio varies from 5 : 1 to 8 : 1. of palms have also been described from the There is no distinct layer of parenchyma Cretaceous of Cutch and Tertiary of Jammu, round the fibrous part of the vascular bun­ Kashmir, by Sahni, 1931 ). dles which may be called tabular paren­ chyma, nor is there any radiating paren­ MATERIAL AND METHODS chyma. The vascular part of the bundles consists of mostly two narrow vessels ( this Both the pieces collected are light greyish­ condition may probably be due to the brown and are 30 em. in diameter. Preser­ heavy crushing during fossilization) placed vation is excellent in both the specimens. side by side. The general ground tissue is Various sections, both longitudinal and quite distinct from that of the dermal zone transverse, have been cut although, as is in that it shows a highly lacunate condition customary with most of the palms, much due to the formation of small reticulations importance is given to the transverse sec­ ( meshes) by the individual parenchymatous tions. No stain has been used since the cells ( PL. 3, FIG. 12). This condition which structures are very clear. is very predominant in the central region thus has its initiative in the subdermal region DESCRIPTION itself. Again, there are no purely fibrous bundles and the leaf traces are very rare. Peripheral Zone - There are three distinct Central Zone - The transverse section zones present as usual with all the palms. shows a large number of rather widely scat­ The extreme which is not present completely tered fibro-vascular bundles with typically is believed to be only a part of the actual irregular orientation in well-preserved lacu­ dermal zone, followed by the well-represented nate network of the fundamental paren­ subdermal and central regions. Cortex, un­ chyma (PL. I, FIG. 2). The fibro-vascular fortunately, is not represented. bundles are orbicular to reniform and gene­ Dermal Zone - In this region the fibro­ rally 100 to 200 [J. only ( PL. 2, FIGS. 4, 5 ; vascular bundles are regularly orien tated PL. 3, FIG. 12). They number 20 to 25 and are rather closely placed (PL. 3, FIGS. per cm. 2 , and the neighbouring bundles are 9, 10). They are mostly elliptical, very 3 to 4 mm. apart. Most of them are pro­ small in size, 50 to 100 [J., and are exclusively vided with two big elliptical or circular provided with a single median elliptical vessels which lie side by side and in general vessel; phloem is not preserved. FIVratio partially excluded. No stegmata are found is about 15: 1. No stegmata or tabular round the bundles. The arms of the scleren-

89 90 THE PALAEOBOTANIST chyma are round and the median sinus con­ and foremost diagnostic feature which dis­ cave. F/V ratio is 2: 1 to 3: 1. Xylem tinguishes it from the other Indian species parenchyma is generally preserved but the is the characteristic nature of its aerenchy­ phloem is not always preserved. No pure matous ground tissue. Of the Indian species fibrous bundles whatsoever are. to be seen. Rode's Palmoxylon kamalam, in which only The most interesting feature is the nature the central part has been described, invites of the ground tissue, consisting of narrow special attention as it shows some similarities rectangular cells often of various shapes with the present species. Palmoxylon kama­ forming loosely fitted meshes with conspi­ lam, while showing the lacunate ground cuous intercellular spaces (lacunae) which tissue, differs greatly from Palmoxylon arco­ are unusually big enough to be visible to tense in having radial parenchyma, in the the naked eye (0,2 to 0·3 mm.). Rarely densely packed nature of the fibro-vascular the cells between the neighbouring bundles bundles in the ground tissue ( 90 to 100 per 2 are regularly rectangular and densely arrang­ cm. ) which are oblong ovate with a flat ed leaving very narrow or no lacunae. complanta type of base where the vascular In longitudinal sections ( PL. 2, FIGS. 6, 7 ) part joins the fibrous zone in the F/V ratio the cells of the ground tissue are small, in which the fibrous portion is almost equal square to rectangular and are arranged in to the vascular portion and lastly, to quote chains. As regards the lignifications of the Rode's words, "just midway between the vessels, they show the usual scalariform plates. neighbouring bundles, the parenchyma cells Leaf traces are sporadic with both dorsal get compressed into linear, dark regions and ventral patches of xylem. which serve to divide the whole ground-mass into distinct compartments", a feature which is wanting in the present species. DIAGNOSIS The only other palm from South India Dermal region with rather closely placed Palmoxylon Pondicherriense described by elliptical fibro-vascular bundles, F/V ratio Professor Sahni (1931) differs from the 15: 1, no stegmata or fibrous bundles; ground present palm in more than one respect. parenchyma rather compact, leaf traces not Palmoxylon Pondicherriense is peculiar in seen. Subdermal region with ovate to orbi­ that the fibro-vascular bundles decrease in cular fibro-vascular bundles, F/V ratio size from without inwards and along with 5 : I to 8 : 1, no stegmata or fibrous bundles, this condition the sclerenchyma too exhibits ground parenchyma highly lacunate due to a change of form. Moreover, there are purely the formation of small reticulations of the fibrous bundles with distinct stegmata. individual cells, leaf traces seen rarely. Among the foreign species Palmoxylon Fibro-vascular bundles in the central region ligerinum Crie ( 1892) re-described in detail scattered rather widely and irregularly, 20 to by Stockmans and Williere (1943) shows 2 25 per cm. , orbicular to reniform, F/V ratio to a certain extent some similarity with the 2: 1 to 3 : 1, ground tissue clearly visible to South Indian species. The nature of the the naked eye, lacunate, lacunae formed by ground tissue is quites imilar ( STOCKMANS& the network of narrow rectangular cells often WILLI ERE, 1943; PL. I, FIG. 4) although of varied shapes, rarely ground tissue between the cells in the longitudinal section of Crie's neighbouring bundles densely packerl leaving species are exclusively spherical rather than little or no lacunae, purely fibrous bundles square or rectangular as in P. arcotense. lakcing, leaf traces sporadic. The similarity ends only there, and the Locality-Near Tiruchhitambalam, about differences are: (1) the presence of purely 8 miles WNW of Pondicherry. fibrous bundles in P. ligerinum; (2) the ten­ Age- Tertiary(?). dency of the formation of a cap of 3 to 4 Type Specimen-No. 1590. layers of densely packed parenchyma round the fibrous part of the bundles (mixed bundles of Stockmans and Williere ); and (3) COM,PARISONS AND DISCUSSION the shape of the bundles in P. ligerinum, the The present species differs widely from the fibrous part being hemispherical with a hitherto recorded Indian species of palm typically flat median sinus. wood (SAHNI, 1943; SHUKLA, 1946 & RODE, It is very interesting to note that the 1933 ), and there is hardly any doubt of its central part of the stem of Livistona, a distinctive nature from them. The first living palm genus, also shows almost all the RAMANUJAM-PALMOXYLON ARCOTENSE SP. NOv. FROM SOUTH INDIA 91 same features. PI. 2, Fig. 8 shows part of and the living palm are so strong as to lead a thin section of the central zone of L. us to name the fossil after the living genus. chinensis. The similarity of structure is However, I believe that unless and until the obvious. Ground tissue is typically lacunate complete stem with the cortical portion is like that of the present species without any available in the fossil condition it may not purely fibrous bundles and the nature of the be advisable to take that step. fibro-vascular bundles also is very similar in the fossil as well in the living specimens. The fossil agrees with Livistona almost in ACKNOWLEDGEMENTS all the characters ( PL. 2, FIG. 3). There is surprisingly, so to say, a layer by layer simi­ I take this opportunity to express my larity in both the fossil and Livistona. sincere thanks to Professor O. A. Hoeg for Professor Kaul has kindly examined the his kind help and criticism during the pro­ sections of the fossil stem and in his opinion gress of this work. I am also very much it is indeed very nearer to the living genus indebted to Professor K. N. Kaul and Dr. Livistona. The similarities between the fossil K. R. Surange for their valuable suggestions.

REFERENCES

·CRIE:, L. (1892). Recherches sur les Palmiers Idem (1946). A silicified Cocos-like palm stem, silicifies des terrains cretaces de I'Anjou. Bull. Palmoxylon ( Cocos) Sundaram, from the Soc. Eludes. Scienl.. Angers. Nouvelle serie. Deccan Intertrappean beds. Jour. Ind. Bot. XXI an nee, Angers, 99. Soc. M. O. P. Iyengar Commemoration Volume. KAUL, K. N. (1935). A classification of the palms Idem (1946). A new species of petrified palm based upon the ground tissue of the stem. stem, Palmoxylon sclerodermum sp. nov. from Proc. 22nd Ind. Sci. Congo Calculta: 285, 286. the Deccan Intertrappean series. Jour. Ind. Idem ( 1938 ). An analysis of the artificial genus Bot. Soc. 22 (2-4): 209-224. Palmoxylon into natural genera. Ibid.: 149.150. SHUKLA, V. B. (1946). Palmoxylon sclerodermum Idem ( 1942 ). The anatomy of the stem of palms Sahni, from the Eocene beds of Nowagaon, and the problem of the artificial genus Palmoxy­ Wardha district, C.P. Jour. Ind. Bot. Soc. 25 Ion. Proc. Linn. Soc. 152 sess.: 65-88. (3): 105-116. RODE. K. P. (1933). Petrified palms from the STENZEL, K. G. (1904). Fossile Palmenholzer. Deccan Intertrappean beds. I-II. Q.]. Geol. Palaeontologie und Geologie Osterreich- Vngams Min. Mrl. Soc. Ind·ia. 5: 75-83. 105-114. und des Orients. 14: 107-287. SAHNI, B. (1931). Materials for a monograph of STOCKMANS & WIELLIERE (1943). Palmoxylons the Indian petrified palms. Butt. Acad. Sci. Paniseliens de la Belgique. Musee Royal d' His­ V.P. 1: 140-144. torie Naturelle de Belgique, Rue Vuntier. 31. Idem ( 1943). Figuration Nou velie de Palmoxylon ·Not seen by me. ligerinum. Ibid. 190.

EXPLANATION OF PLATES

PLATE 1 6. P. arcotense. Longitudinal section of a part of the stem. x 200. 1. A view of the fossiliferous locality. 7. Part of section in Fig. 6 enlarged. X 400. 2. Palmoxylon arcotense sp. nov. Cross-section 8. Livistona chinensis. A part of the central of the central part showing the irregular distri­ region of the stern. X 200. bution of the bundles in the lacunate ground tissue. X 2. PLATE 3

PLATE 2 Figs. 9-12 - Palmoxylon a1'cotense sp. nov. 9. A part of the outer region showing the dermal 3. An enlarged fibro-vascular bundle from the ( not complete) and subdermal zones. x 2. central part of Livistona. x 400. 10. Dermal zone enlarged. x 10. 4. P. arcotense. Fibro-vascular bundle with ellip­ 11. Subdermal zone enlarged. Note the typically tical vessels. X 200. lacunate ground tissue. x 10. 5. P. arcotense. The ground tissue between the 12. A fibro-vascular bundle from the central two neighbouring bundles. X 200. zone. x 200. N

..J 0 ;>

... ~ >:...... , .-'i· - .~ ~ h. ~.'.... ~f- ~ . '1Ji:J..~.. - .: ,",,' .. ~...f .. 'V "'. ,'" .... ,...... 5"'· ",,. ,.'" .,..-...... ~.,...~ .. : ." ...... "i1'..~.-.~ ..~... ;'",~ ..... '1'.;-' .~. ," '~". • '.,'1..' ~·~;~il." .>"'~\, vt''' ...• ~ ''''~.!M'~ ,~.~. ,(.}';r.~~,t.s·"r~\~ ..,"~~."1 .. ... ~~.. "'.. iY"r,tl- ."., .' :('·:~~"~::;~...... ~~:~4--4"",t"~~.c.._,.. :il:~~-oii!Li.'~., ,,' . N ...... : i.. "':;e!"J.,: ~.' rrc:- ...~... ij,,£~ ..i ..•~ !. ••~ ' ••", ,'" - 0 .':~.~:' 0 >- - ',," ~~ ~.,.,.:.'t·.....,l1·---:~;£1·· ': ','.~; ,', -. f-: .~ .. ~:~ . ,~'.~', ".£.',::'.>•.,',,; ~ ~"'i\;:: ~ Z • "'.4l:t"".r;1iI~',:''';'' '~."" ~10l:.·..• _ ~.'">_,.;'"t. . "., -<: .' ,;V,l ,' ...".. 'So • !-< -~ .'!!'~.., 0 . :;'....~,~.y ,:. ~' .. <0 . '. ;.. fJI'-~..... ~~..,:....'tJ.. ,Y 0 , ._.'~., .. ~ ~. l>l 1· ~ . i:~~;:".!,..: ... ~- .... , .- ". ...O(• .• -. " • ~ • 'J.- .... ~ _., 0.." .'- ~~"!! . ""-••- -'; ~;,.~k:-.rll; .... ~ .~ .. ,• .". "."!JI' Qv." l>l - ..