Great Basin Naturalist

Volume 41 Number 1 Article 10

3-31-1981

Ultrastructure of Eocene fossil plants

E. M. V. Nambudiri University of Dar es Salaam, Dar es Salaam, Tanzania

W. D. Tidwell Brigham Young University

W. M. Hess Brigham Young University

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Recommended Citation Nambudiri, E. M. V.; Tidwell, W. D.; and Hess, W. M. (1981) "Ultrastructure of Eocene fossil plants," Great Basin Naturalist: Vol. 41 : No. 1 , Article 10. Available at: https://scholarsarchive.byu.edu/gbn/vol41/iss1/10

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. ULTRASTRUCTURE OF EOCENE FOSSIL PLANTS

E. M. V. Nambudiri,' VV. D. Tidwell,- and W. M. Hess-

Abstract.— Petrified leaf and pericarpic tissues from the Eocene Deccan Intertrappean beds of India were stud- ied using light and transmission electron microscopy. Degradated cytoplasm with organellelike bodies are present in cells of the leaf tissues. TEM of these cells revealed wall structure and cytoplasmic residues. Microfibril distribution of pericarpic cells resembles fiber cells in extant angiosperms.

Scanning and transmission electron micro- Deccan fossils have been attempted. Hence, scopes are widely used in studying fossil the present work forms a unique attempt at plant material. Chaloner and Collinson describing the ultrastructure of these fossil (1975) demonstrated that additional informa- plant tissues. tion on impression fossils could be obtained by using SEM. Grierson (1976), Hartman Material and Methods (1977), and others have studied SEM struc- tures of the vascular tissues of Devonian The petrified fossil tissues are embedded in plant fossils. Several workers, notably Kedves black cherts. Peel transfers of these fossil tis- (1974), Pettit (1966), Taylor (1968, 1973a, sues were cut into 1-2 mm pieces. They were 1973b), Taylor and Millay (1969, 1977a), and then placed in 1 percent OSO4 for four to six others have reviewed the usefulness of scan- hours. The sample pieces were transferred ning and transmission electron microscopy in from OSO4 and embedded in agar (2 per- paleopalynological investigations. cent /HoO), to prevent disintegration in em-

It was Wesley and Kuyper (1951) who, for bedding solvents. The material was then al- the first time, demonstrated that TEM could lowed to remain in Uranyl acetate overnight. be used in studying the vascular tissues of Le- After dehydration by processing through a pidodendron. Since then, Eicke (1954), Fry series of ETOH and acetone concentrations, (1954), and Schmid (1967) have employed the material was embedded in Mollenhauer's TEM in studying vascular tissues of fossil resin (1964). Ultrathin sections were sub- plants. sequently prepared. Crepet et al. (1975) and Dilcher (1974) ex- the microscopy studies to tended electron Results and discussions fossil angiospermic leaves and inflorescences.

Niklas et al. described structures (1978) TEM Leaf Tissues of Miocene angiospermic leaves resembling Zelkova from the Succor Creek Formation of Several well-preserved petrified leaf tissues Oregon. Apart from these, the authors are were embedded in a black chert. Epidermal imaware of any other TEM studies on petri- cells of the leaf tissue are rectangular (Fig. 2) fied angiospermic tissues. Therefore, two dif- and many of these cells contain cytoplasm ferent plant tissues from the Eocene Deccan and organellelike bodies (Figs. 2 to 4) repre- Intertrappean series of India were processed senting various degrees of disintegration. for ultrastructural studies. These Inter- From their consistent peripheral orientation, trappean beds contain some of the best pre- the round to oval organellelike structures served petrifactions from India, and until (Fig. 2) are similar to the distribution of now no electron microscope studies of the chloroplasts in extant angiospermic leaves. A

'Department of Botany, University of Dar es Salaam, P.O. Box 35060, Dar es Salaam, Tanzania. -Department of Botany and Range Science, Brigham Young University, Provo, Utah 84602.

161 162 Great Basin Naturalist Vol. 41, No. 1

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Fig. 2. of epidermal cells from the petrified Fig. 1. Light micrograph of the epidermal cells of the One the fossil leaf tissue, SOX. leaf tissue enlarged (light micrograph). Arrows point out the round to oval organellelike bodies, 850X.

Fig. 3. A single cell of the Eocene leaf tissue, demon- Fig. 4. Cell of the fossil leaf, showing degradated strating its internal structure (light micrograph), 7.50X. cytoplasm (light micrograph), 1300X. March 1981 Nambudiri et al.: Fossil Plants 163

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micrograph), Fig. 5. Stnicture of cell wall: middle lamella, isotropic layer, and secondary wall are visible (electron 13,000X.

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28,800X. Fig. 6. Cytoplasmic residues inside the cells of the fossil leaf tissue (electron micrograph), 164 Great Basin Naturalist Vol. 41, No. 1 region thought to represent cytoplasm (Figs. to the cell walls (Fig. 6). An electron-dense 3 to 4) has undergone considerable degrada- organic matter is occasionally present in the tion (Fig. 4), and whether a nucleus is pre- cytoplasmic residue (Fig. 7). The electron- served or not is a matter of conjecture. dense nature of this material is perhaps due The presence of protoplasmic material in to the unsaturated bonds that have reacted acid is not fossil plant tissues is well documented by sev- with the osmic and probably from eral workers. Taylor and Millay (1977a) sug- the coalification process. These are evidently or represent gested that cytoplasm and nuclei could be not artifacts, but may may not part of the cytoplasm. preserved in the microspores of the Pennsyl- vanian cone genus, Lasiostrobus. They later Pericarpic Tissues showed evidence for well-preserved cytoplas- pericarpic tissues processed for mic material in Biscalitheca spores (Taylor The TEM studies are from peel transfers of Viracarpon and Millay 1977b). In Lepidostrobus schopfii Sahni, a monocot fruit of Pandanaceous affi- (Brack-Hanes and Vaughn, 1978) and Zelkova nities (Nambudiri and Tidwell 1978). The (Niklas et al. 1978), nuclear material and mesocarp of the phallanges in Viracarpon is cytoplasmic residues have been reported. formed of thick walled parenchymatous and Chlorophyll derivatives were recovered from fibrous tissues. The parenchymatous cells are the Eocene formations of East Germany (Dil- moderately thick walled and isodiametric. cher et al. 1970) and Miocene Zelkova leaves The sclereids, on the other hand, are highly (Niklas and Giannasi, 1977). Baxter (1964) re- thick walled brachysclereids. The electron ported starch grains in Pennsylvania fossil micrographs (Figs. 8 and 9) are of structures gametophytes. The presence of protoplasts, similar to the secondary wall layers of fiber although somewhat degradated, in the petri- cells. The microfibril distribution in the per- fied leaf remains from the Deccan Inter- icarpic cells (Fig. 9) suggests similarities with trappean beds, therefore, adds another ex- the gelatinous fibers of many extant plants ample of the preservation of cytoplasm and such as Celtis sp., Acer saccharum and Popu- organellelike bodies in plant fossils. Relative- lus sp. (Cote and Day, 1962). These authors thus, the preserva- ly low degradation and, observed a gelatinous layer around the sec- organellelike bodies tion of cytoplasm and ondary walls. The longitudinal splits that tra- rapid deposition in may have resulted from a verse the secondary walls (Fig. 2) could cor- the numerous lakes that occupied the Deccan respond to the terminal lamellae reported for region in the Eocene period. the tension wood fibers in Popuhis (Cote and Cells of the leaf tissues, on the other hand, Day 1962). (Fig. resembles retain a wall structure 5) that From this brief TEM study of the leaf and parenchymatous cells in extant angiosperms. pericarpic tissues from the Deccan Inter- electron-dense layers are apparent with Two trappean beds of India, it is evident that the an isotropic layer between them. At the cen- application of electron microscopy to supple- ter, where cell walls meet, the middle lamella ment the anatomical data would further en- attains maximimi thickness. The middle la- hance closer comparisons with extant genera mella is an electron dense layer, and repre- of angiosperms. sents a compound middle lamella as in the fossil genvis, Callixylon (Schmid 1967). Sever- Acknowledgments al extant angiosperms such as species of Fop- The authors are grateful to Drs. Karl J. ulus (Chafe and Chauret 1974) have similar Niklas, Cornell University, Ithaca, New York, middle lamellae. The inner electron dense and David L. Dilcher, Indiana University, layer corresponds to the inner secondary Bloomington, Indiana, for helpful sugges- wall. Thickness of the isotropic layer (Fig. 5) tions. For technical asistance we thank Mrs. is, perhaps, exaggerated by shearing of the Connie Swensen. material. SI, S2, and S3 layers, as found in lignified tissues (Schmid 1967), are in- Literature Cited distinguishable in this fossil material. Cyto- Baxter, R. W. 1964. Paleozoic starch in fossil seeds from plasm has undergone considerable degrada- Kansas coal balls. Trans Kansas Acad. Sci. tion. Cytoplasmic residues are foimd adjacent 67:418-422. March 1981 Nambudiri et al.: Fossil Plants 165

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Fig. Electron dense carbonaceous matter inside the 7. pjg g Pericarpic tissue of Viracarpon, illustrating the cells of the fossil leaf tissue (electron micrograph), ,^^^^^1,^ (electron micrograph), 28,800X. 13,000X. * ^

Fig. 9. Electron micrograph of pericarpic cells of Viracarpon, showing microfibril distribution, 28,800X. 166 Great Basin Naturalist Vol. 41, No. 1

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