Studies on the fossil flora of Nipania (Rajmahal Series), India - Pentoxyleae

Abstract

The paper describes several new anatomical details regarding the vegetative remains of the Pentoxyleae. In the genus Pentoxylon Srivastava stems possessing more (8-9) or less (3-4) than the usual number of the steles are described. Besides the scalariform pitting, bi-and multiseriate medullary rays-characters not known before-are also described. The genus has been diagnosed for the first time. The apical region of a dwarf shoot of Pentoxylon sahnii is described. The genus Nipaniophyllum Sahni is reinvestigated and consequently the diagnosis of both the genus and the species N. raoi Sahni emended. The stomata in the genus are shown to be non-bennettitalean in nature. The stems of Nipanioxylon guptai Sriv. are described. In the light of new information along with the previously known facts it is shown that the Pentoxyleae is not a synthetic group and belongs to the Cycadophyta. It is the most primitive group amongst the cycadophytes and should rank with the Benuettitales and the Cycadales.