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Elkinsia gen. nov., a Late Devonian Gymnosperm with Cupulate Ovules

G. W. Rothwell, S. E. Scheckler and W. H. Gillespie
Botanical Gazette
Vol. 150, No. 2 (Jun., 1989), pp. 170-189
Stable URL: http://www.jstor.org/stable/2995234
Page Count: 20
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Elkinsia gen. nov., a Late Devonian Gymnosperm with Cupulate Ovules
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Abstract

An extensive collection of fossilized ovules, ovulate cupules, and cupuliferous branching systems from late Devonian deposits of eastern West Virginia is described and named Elkinsia polymorpha gen. et sp. nov. Elkinsia cupules are borne at the tips of cruciately forking axes that show a moderate level of overtopping. Cupules are 1.0-1.8 cm long and 0.6-1.2 cm in maximum diameter. The cupule is constructed of slender axes that fork twice to produce four quarters; each quarter terminates in one ovule and four sterile tips. Ovules are 3.5-7.0 mm long and isodiametric in transverse section, with an integument of 4-5 lobes that are fused together only in the basal third of the ovule. The nucellus is terminated by a large, dome-shaped pollen chamber that is surmounted by a tubular lagenostome. There is also evidence of a central column that indicates Elkinsia had hydrasperman reproduction. Elkinsia is compared to the other Devonian ovulate cupules Moresnetia zalesskyi, Archaeosperma arnoldii, Xenotheca devonica, and Kerrya mattenii, and all are found to be basically similar in cupular architecture and ovule structure. However, these Devonian gymnosperms show several consistent differences in either their cupule morphology or ovule morphology or in both; they also may have differing architecture of the cupuliferous branching systems. This demonstrates a wider than expected diversity among Late Devonian gymnosperms and reveals that knowledge of the structure of both the ovule and the cupule is necessary for separating some taxa.

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