A revision of Cassinia (Asteraceae: Gnaphalieae) in Australia. 1. Introduction and generic and infrageneric considerations

Abstract

The nomenclatural and taxonomic history of Cassinia R.Br. is reviewed, particularly in relation to its close relative Ozothamnus R.Br. Current concepts of Ozothamnus are shown to be unsatisfactory, with that genus consisting of a 'core' of approximately 25 species (including the type species O. rosmarinifolius R.Br.) which are defined by their possession of inner phyllaries with radiating tips and no paleae (or only very few) between the florets, and other characters. The other 25 species (approximate) of 'Ozothamnus' need re-examination and probable placement elsewhere (but not in Cassinia). Cassinia can be satisfactorily defined as a genus distinct from 'core' Ozothamnus. As a precursor to a series of papers describing the species of Cassinia (including a large number of new taxa), Cassinia is divided into two subgenera, seven sections and two series. New taxa described are Cassinia copensis Orchard, Cassinia subg. Achromolaena (Cass.) Orchard, Cassinia sect. Complanatae Orchard, Cassinia sect. Venustae Orchard, Cassinia sect. Leptocephalae Orchard, Cassinia sect. Costatae Orchard, Cassinia sect. Arcuatae Orchard, Cassinia (sect. Cassinia) ser. Cassinia and Cassinia (sect. Cassinia) ser. Longifoliae Orchard.