Venation patterns in some early Glossopteris

Abstract

Glossopterids were the dominant plants in Gondwana during the Late Permian. They characterized the plant assemblages and gave their name to the flora of the time. Although Glossopteris is characterized by anastomosing secondary venation, the oldest known forms placed within this form-genus often have only rare cross connections between adjacent parallel secondary veins or possibly none. At least some of the taxa placed within the form-genus probably evolved from plants that bore leaves with dichotomously branched secondary veins.