XVI International Botanical Congess

The problem of land plant origins involves a search for fossils links of the early higher plants to their putative algal ancestors. Thallic algae-like plants were studied from the Upper Silurian to Lower Devonian of Podolia and the Lower to mid Devonian of Siberia and Kazakhstan. They include forms previously assigned to Baragwanathia and Cooksonia, the earliest higher land plants. Revision of the Podolian material have show n that these fossils are actually non vasicular alga-like plants with certain morphological features of higher land plants. Flabellate + leaves + from the Devonian of Kazakhstan are reinterpreted on the basis of SEM studies as fossil lichens. Previous data on Orestovia and other alga-like fossils are reconsidered in the light of the latter discoveries and the role of symbiogenesis in the higher plant origins is discussed.