By Pant, D.D. and Osborne, R. and Birbal Sahni Institute of Palaeobotany

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Extra info for An introduction to gymnosperms, cycas, and cycadales

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A-C, diagrams of longisections of abortive ovules in the female flower showing median abortive nucelli flanked by two sterile lobes. D, diagrammatic transections through dichotomised apex of a sterile scale. E, diagrammatic transections through the apex of a megasporophyIl from a telomous system with a fertile telome in the miodle flanked by tW<1lateral sterile telomes (all after Florin, 1951 but"~ G redrawn modified). \ s c,c If. \~lr·/h \. , .. b> .... ~ ~ ; .. ' s ®J Fig. 9. Lyrasperma scotica.

8). In Lyrasperma (Long, 1960c; Fig. 9), which is possibly a pteridosperm and Maheswariella bicornuta (Pant & Nautiyal, 1963a) of uncertain affinities, the distal ends of the two sterile integumentary telomes are still free and project upwards in the form of two lateral horns. Possibly the integument of the anatropous seed of Buriadia heterophylla (Pant & Nautiyal, 1967) was formed from a forked appendage (like the forked leaf of Buriadia) where one lobe bore a megasporangium and the other was sterile.

The Telomic Theory is basically similar to the synangial theory but the telomic theory believes that initially a centroterminal fertile telome or megasporangium became enclosed by a number of surrounding sterile telomes which fused with each other (Fig. 13) to form an integument. The centroterminal fertile telome could have been like the megasporangium of Stauropteris bumtislandica. s. 9). Pant (1966) explajns the formation of 33 platyspermic seeds of Buriadia by a single sterile telome and a me some (Fig.

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