The taxonomic significance of the term Psilopsida and the evolutionary trends of this plant phylum

Abstract

The taxonomical significance of the term Psilopsida is discussed in this article. As a special plant phylum the Silurian-Devonian Psilopsida sensu stricto are regarded as an independent intermediary cryptogamic vascular type standing between the Bryophyta and all true pteridophytic plant phyla and exhibiting its own peculiar evolutionary trends. The opinion is suggested that we have to investigate these special evolutionary trends quite independently and irrespectively of the evolution of the single pteridophytic phyla. Several of these trends are indicated.