MARSILEALES AND SALVINIALES — “LIVING FOSSILS”?

On the other hand I agree with Zimmermann that the differences mentioned by Thomas and by Harris are not so important as to preclude any relationship. However, the interpretation of a possible relationship must be based on an entirely different assumption, viz., that instead of Marsilea being a form descended from the Caytonialian ancestors, the Caytoniales descended from a group of more primitive plants of which the Marsileaceae are the survivors. I am personally convinced of the fact that the basic ancestral stock of the Caytoniales, the Cycadophyta and ultimately of the Angiosperms is to be sought among the Glossopteridales. Consequently, the above-mentioned suggested derivation of the Caytoniales from Marsileaceous ancestors According to current opinion (see, e.g., Christensen 1938, Reed 1954, Zimmermann 1959, Pichi-Sermollx 1959) there is no close relationship between the Marsileales and the Salvineales, so that they should not be united into one class as “Hydropteridales”. Their taxonomic position with regard to the Filices Leptosporangiatae, to which class they have up to now usually been referred, has always