A Taxonomic Study of Species of the Genus Vaucheria Collected in California

Abstract

The genus Vaucheria is one of the best known and most widely distributed members of the Chlorophyceae. Its frequent occurrence, both on damp ground and in shallow ponds and streams, its conspicuous size and unusual reproductive structures account, no doubt, for the extensive taxonomic study that has been given it for over a century. The genus is so familiar to botanists that it is unnecessary to present a discussion of its generic characteristics and modes of reproduction. As is also well-known, the differentiation of species is based almost entirely upon the structure of the reproductive organs, a system initiated by Vaucher (I803). European botanists have devoted considerable attention to systematic studies of the genus, the best recent treatment appearing in the volume by Heering (I92I) on the Siphonales and Siphonocladiales in Pascher's wellknown series. While species of Vaucheria have been frequently collected and identified by American botanists, and are included in lists of algae reported from many parts of the country by Transeau, Tiffany, Setchell and Gardner, and Taylor, the only taxonomic treatments of all American species are those of Wolle (I887) and of Collins (I909). The recent monographic treatment of the Vaucheriaceae by Miss Brown (I929) is largely a compilation from the works of Heering (I92I) and of Collins (I909), but completely ignores the logical division of the genus into sections as presented by these and other authorities. Since the various American workers on the group are in marked disagreement as to the exact nature of the specific limits of representatives of the genus found in this country, it was suggested to the writer by Dr. G. M. Smith that a careful study of a large number of collections might give a more clear-cut conception of the various species, and in addition might reveal members of the genus not previously reported from America.