The rapid appearance, expansion, and relatively quick extinction of this group, as well as the large number of species, has made the group very important for understanding paleobiogeography , specifically in the recognition of areas that were once connected together, but are now separated through the action of continental drift. As a result, there is a wealth of descriptive literature available on glossopterids. However, most of the available fossils are sterile leaves lying unattached to stems, and so a number of species which have been described are not well differentiated, and few are known from distinctive reproductive structures. This makes it difficult to be certain of the actual number of species. The large number of leaves found preserved, and the character of the deposits in which these are found, suggest that glossopterids were deciduous , losing their leaves in the autumn, and growing new leaves in each spring.
Some specimens show an abscission zone , such as that along which a leaf detaches in living plants.
Mature leaves were often 10 cm long, and some leaves have been found over a meter in length. These mature leaves are very easy to recognize, since they have a strong central vein and a network of smaller veins. This is quite different from the other seed plants of the Late Paleozoic and early Mesozoic , which usually had no midvein and secondary veins which ran parallel to each other. You can see the striking preservation of these vein networks in the picture below. The pictures above show features of Glossopteris leaves.