XVI International Botanical Congess

Many phylogenetic characters of Gondwana seed ferns have been ambiguous, as they were often based only on compression/impression material. We report new discoveries of compressions of the common foliage Dicroidium (corystosperms) with attached reproductive organs from the Late Triassic of Antarctica. Stems bear typical Dicroidium fronds and lateral short shoots to which are attached unusual Umkomasia cupulate organs. Each consists of an apical whorl of 4-5 uniovulate cupules. Permineralized glossopterids from the Late Permian of Antarctica include an ovule-bearing megasporophyll that compares morphologically to that known from the Bowen Basin, but establishes that the ovules were borne on the adaxial surface. Other permineralized material includes uniovulate cupules, each attached to a long stalk, similar to the impression genus Denkania. The Gondwana specimens offer an opportunity to test the relationship of these lineages in light of current hypotheses on seed plant evolution.