Indian Williamsoniaceae-an overvIew B. D. Sharma Sharma BD 1992. Indian Williamsoniaceae-an overview. Palaeobolanisl 40 260·265. The morphology, anatomy and phylogeny of the known extinct representatives of the family Williamsoniaceae from India have been overviewed. The family occurs in the Upper Mesozoic rocks and is represented by fronds, stems, male, female and bisexual fructifications. Though the fronds vary in shape, size and venation, all possess identical syndetocheilic stomata. The stems Bucklandia and Sahnioxylon show minor variations in struc1ure of tracheary elements and are related with cycadeoideas and homoxylous angiosperms. The male fructification Wellrichia is built on very distinct and different plan than the seed-bearing fructification- Williamsonia, which has been derived from Cordaianlhus. The bisexual fruclification-Amarjolia is terminal and exposed like Williamsonia, while in structure and arrangement of microsporophyll resembles Cycadeoidea. Relationship among different organs is suggested and phylogeny of Williamsoniaceae is discussed. Key-words-Williamsoniaceae, Morphology, Phylogeny, India B. D Sharma, Deparlment of BOlany, University of jodhpur, jodhpur 342001, India. mllT ~ ~ f4\'\WHftf"ll{f11 ~ otT 0 it0 '!fTl1f ~ ~ ~ ~ ~ ~;oqft lf~ 'lffi(f <t f4f'<14I1fi1f"lt:J><ll' ~ ~ fllfur ~ ~ <ft ~, .!llrtn: t:;cf <ft <ft I ~ it ~ t (f?f[ ~ ~ ~ ~ 'fCf'If, (f'fT (f?f[ "", "lro 't:':'f ,,~ ~ ft1<:rn ~ I 'fCf'If ~ 3lTiffl: (f?f[ Arn.1"llffi it ~ mm~ ~ ~3lT ~ ~ ~ ~ ~ ~ ~m 'Rtmr m (f'!Tfq- it mlR<IT t I t:;cf cR it it m'\r>!m ~ il~?I~fq;41 ~ ~I ~-UlTil' ~1T (f?f[ it ~3l'f4itm ~ 311~(1<l'1'i\)~1 <t G<ffif m 'f.<'f'f f4f<1<ll\Wf"l4i ctit "" ~it~f\1';rtl~-UlTil'~ctit~~~<t~~1,,~~-3\l\(J"'1f<14i~~~mrr~(f?f[f4f<1Ql\Wf"lQi ~ ~ <t~ m~1 ~~u ctit 'llffu Il<ftcr mrr tl t:;cf it <1€1,<l'1"1l o\q of tll$4>1ll3IT$IllQi G<ffif M\r?r 3JG!ll'if it ~ ~ ~ ~ ~ ~ f'<l;:V; lTit g (f?f[ f4f<1Ql\Wf"lQi ctit <ft I FAMILY Williamsoniaceae, belonging to the class spread with two rows of appendages on which Bennettitopsida, flourished and dominated the microsynangia are produced. Ovules/seeds are vegetation during the Mesozoic Era (Harris, 1969). produced intermingled with sterile scales in a Members of this family originated sometimes during compact layer covering the receptacle. In bisexual Middle Triassic and disappeared by the end of Lower fructification baloon-shaped microsporophylls Cretaceous. The family includes extinct plants in encircle the central receptacle with a covering of which the stem surface has spirally arranged ovules and sterile scales. rhomboid leaf bases, parenchymatous pith and In India, members of this family occur at several cortex well developed with mucilage ducts; vascular Mesozoic localities, e.g., Rajmahal Hills, Bihar; zone narrow made up of collateral, conjoint and Golapilli near Elore; Madras outliers, )abalpur, endarch bundles; secondary wood mano-or )aisalmer, Kachchh, etc. (Oldham & Morris, 1963; picnox)r\ic; leaf trace is unilacunate. Leaves are Feistmantel, 1876, 1877, 1879; Seward & Sahni 1920; pinnate or partly pinnate, with parallel or reticulate Sitho!ey, 1954; Gupta, 1966; Sharma, 1967a, 1977, venation; stomata transverse to veins and syndetocheilic. Fructifications are terminal, exposed, Four Decades of Indian Palaeobotany seed-bearing and bisexual. Microsporophylls are Editors: B. S. Venk3t3chala & H. P. Singh Publisher: Birbal Sahni Institute of Palaeobotany, Lucknow SHARMA-INDIAN WILLIAMSONIACEAE-AN OVERVIEW 261 1990; Bose, 1953a, 1953b, 1968; Bose & Kasat, India. Search should also be made to find out their 1972a; Bose & Banerji, 1981, 1984). The associated stems and fructifications. Williamsonian fossil plants described from the Indian rocks are: Pteropbyllum Brongniart Fronds-Ptilophyllum (18 sp.), Pterophyllum (10 Frond pinnate, pinnae linear, base syrnmetrical sp.), Otozamites (7 sp.), Anomozamites C3 sp.) and attached on lateral side of rachis, apex acute, obtuse Dictyozamites (7 sp.). or truncate, veins parallel with few forkings. Stems-Bucklandia (4 sp.) and Sahnioxylon (2 Epidermal and anatomical characters of Indian sp.) species are not known. Oldham and Morris (1863) Male jructzfication- Weltrichia C3 sp.) and Feistmantel (1877) identified a number of Seed-bearing jructzfication- Williamsonia (12 species of this genus from India, but Seward and sp.) Sahni (1920) merged many of these species into the Bisexual jructijication-Amarjolia (1 sp.) genus Nilssonia Brong. Sharma (l969b) also Plant remains of Williamsoniaceae occur as transferred two species of Pterophyllum into impressions, incrustations and petrifactions. The Nilssonia. On the other hand Bose and Benerji impressions show external morphology. In (1981, 1984) rE:transferred all known Nilssonia incrustations the epidermal characters are studied species from India into Pterophyllum species through maceration and peel techniques using nitric without studying the epidermal and anatomical acid as etching acid (Jacob & Jacob, 1954; Bose & characters. Kasat, 1972a; Bose & Banerji, 1981, 1984; Sukh-Dev & Rajnikanth, 1988a, 1988b). The petrifactions have Otozamites Braun been studied by the usual method of cutting, Frond pinnate, pinnae small to linear to grinding and polishing techniques. At Amarjola, the triangular or round; base asymetrical and auriculate, material 'being soft and fragile needs cooking in apex acute, obtuse or round; veins diverging and Canada balsam prior to sectioning. Canada balsam is dichotomised. Epidermal cells sinuous, stomata used as mounting medium. Sometimes, the polished hypostomatic, syndetocheilic and restricted to surface is examined with a water film under stomatal bands. reflected light. Oldham and Morris (1963) and Feistmantel (1876, 1877, 1879) described a number of species of DESCRIPTION this frond genus from India. Seward and Sahni (1920) merged many of the species into the genus A systematic account of the extinct plants of Ptilophyllum. Roy (1963) described Otozamites Williamsoniaceae known from India is given as bellus from Kachchh. Bose and Banerji (1981, 1984) under: described the morphology and epidermal characters Fronds of O. imbricatus Feistmantel 1876, O. Ptilophyllum Morris Walkamotaensis Bose & Zeba-Bano 1981, 0. kachchhensis Bose & Banerji 1984. Otozamites Frond pinnate, pinnae linear to round, base occurs more frequently in the Mesozoic rocks of asymetrical, upper basal angle round, lower Kachchh than any other exposure in India. decurrent; apex acute, obtuse, truncate or round; veins parallel with forkings. Epidermal cells mostly Dictyozamites Oldham sinuous, stomata hypostomatic, transversely oriented and syndetocheilic. Rachis with a number of bundles Frond pinnate, pinnae linear, falcate or round, arranged in double U-manner. base asymetrical and auriculate, apex acute, obtuse Sharma (1967a), Bose and Kasat (1972a) and or round, venation reticulate, stomata hypostomatic, Bose and Banerji (1981, 1984) published reviews on syndetocheilic and restricted to stomatal bands. the Indian species of the genus Ptilophyllum and Rachis has vascular bundles arranged in double U­ identified 18 species. Some of these fronds are manner similar to that of Ptilophyllum (Bose & Kasat, morphologically alike but separated on epidermal 1972a). In Dictyozamites, the number of areoles characters, e.g., P. nzpanica Mittre 1956, P. indicum present in the middle of pinna is used in the Jacob & Jacob 1954, P. sahnii Gupta & Sharma 1968. identification of species. Seven species, viz., D. Minor variations in morphological and epidermal jalcatus Oldham 1963, D. indicus Feistmantel 1877, characters may be due to environmental differences D. hallei Sahni & Rao 1933, D. sahnii Gupta & and age of the frond. A re-investigation is likely to Sharma 1964, D. jeistmantelii Bose & Zaba-Bano reduce the number of species of Ptilophyllum in 1978 and D. gondwanensis Sukh-Dev & Rajnikanth 262 THE PALAEOBOTANIST 1988a are known from India. Associated stems and are also seen. Whether Sahnioxylon had leaf bases fructifications are yet to be discovered. on surface and what kind of leaf traces were present, is yet to be discovered. Anomozamites Schimper Fructifications Frond lobed or pinnate, pinnae unequal, base symmetrical, attached on lateral side of rachis, apex Weltrichia Braun obtuse to truncate, veins parallel with forkings. This male fructification was described earlier Epidermal cells sinuous. Stomata hypostomatic, under the generic name Williamsonia. Sitholey and transversely oriented and syndetocheilic. Important Bose (1953) instituted Williamsonia santalensis species of the genus known from India are: A. jissa which was later on transferred to Weltrichia (Feist.) Sharma 1969b, A. amarjolense Sharma et al. santalensis by Sitholey and Bose (1971). Sitholey 1971, and A. haburensis Bose & Banerji 1981. and Bose (1953) described a single whorl of Associated stems and fructifications remain microsporophylls surrounding a cup-shaped unknown. receptacle, while Sharma (1969a) on the basis of Stems-Bennettitalean stems are simple or study of more than 50 specimens, some ofwhich are branched and possess spirally arranged rhomboid nicely preserved counter parts, suggested two leaf bases on the surface. Two stem genera, viz., whorls, i.e., the abaxial of sterile bracts and adaxial Bucklandia Pres!. 1825 and Sahnioxylon Bose & Sah of microsporophylls. Si tholey and Bose (1971) did 1954 are known from the Indian rocks. not agree to it. Each microsporophyll has two rows Bucklandia Prest. of appendages on which parallel rows