On the oldest representative of the family characeae and its relationships with the porocharaceae

Abstract

The paper records the discovery of the oldest representative of the family Characeae, Aclistochara aff. jonesi, in the Liassic freshwater Kota Formation, Gondwana Group of the Pranhita- Godavari Valley, Peninsular India. The species occurs in lime- mud sediments which are considered as having been deposited in brackish-water lakes with periodic oscillations of water-level under arid conditions. From the palaeontological point of view, the closure of the apex by the ends of the calcified spiral cells is interpreted as a xerophytic structure allowing the plant to persist during intervals of dessication. The increase of the average diameter of the apical pore of germination from Porochara to Aclistochara and Lamprothamnium is demonstrated. © 1991 Taylor and Francis Group, LLC.