Early land plant developments: Global progress and Indian priorities

Abstract

This review paper is primarily aimed to furnish a general account on the origin, evolution, radiation and the proliferation of early land plants on the earth. The story of the emergence of the plant life on the land and its subsequent development during Silurian and Devonian times has been narrated as per Edwards and Selden’s (1993) theory of gradual colonization, which shows that the land plants established themselves involving four stages of continuous growth and the diversification. The paper demonstrates how the simplest land forms (Cooksonia, rhyniophytes) in the middle Silurian have given risen to much evolved progymnosperms (Archaeopteris) during the late Devonian within a span of 48 million years of time (from 423-375 ma). An account of the records of land plants from their earliest occurrences in the Ordovician to the end of Lochkovian in the Lower Devonian has been provided to show the current status of such studies on the global platform. The palaeo-phytogeography concerning spores and megafossils from Llanvirn (middle Ordovician) to Lochkovian (Lower Devonian) has also been depicted on the base maps of the globe.