Generic Status of Glossopteris, Gangamopteris and Palæovittaria

Abstract

THOUGH the Glossopteris flora has been known for more than a hundred years now, our knowledge of this flora does not extend beyond the gross features of the plants comprising it. As is well known, the fronds of the three important genera, Glossopteris, Gangamopteris and Palæovittaria are more or less similar in external form and are usually distinguished by the presence or absence of midrib and anastomosing of the secondary veins. But many times the characters of one genus merge into another and then it becomes difficult to refer it definitely to any one of the three genera. Some good examples are, Glossopteris mitchelli, Glossopteris intermittans, Glossopteris decipiens and Gangamopteris indica. Owing to such inconsistency shown by these external characters, doubts were raised in the past about the generic status of Gangamopteris and Palæovittaria. It appears that between the three genera there are no sharply defined distinguishing features, and the criteria like the presence or absence of midrib and the anastomosing of secondary veins are too inconsistent to be relied upon as generic characters.