Glossopteris, a genus of fossilized woody plants known from rocks that have been dated to the Permian and Triassic periods (roughly 300 to 200 million years ago), deposited on the southern supercontinent of Gondwana. Glossopteris occurred in a variety of growth forms. Its most common fossil is that of a tongue-shaped leaf with a prominent midrib and reticulate venation. Glossopteris leaves are commonly found in thick mats, and thus some authorities speculate that the plants were deciduous. It reproduced by seeds, and a tremendous variety of both ovule-bearing and pollen-bearing reproductive structures are borne on characteristic Glossopteris leaves. Before the last of this group finally succumbed to extinction at the end of the Triassic Period, Glossopteris became one of the major features of the flora of Gondwana. The distribution of this plant was among the first evidence for continental drift.