The genus Triodia R. Br. (Gramineae)

Abstract

The material of Triodia R.Br. available in Australia was used as a basis for a revisory study of the genus. Relationships between the species and the affinities of the genus with Plectrachne Henr. and Danthonia DC. are discussed. The opinion is expressed that the genus is better placed in the tribe Danthonieae than in the Eragrosteae. Consideration is given to the possible history of the genus in the light of recent papers on past climatic conditions in Australia. A key is provided for the identification of 28 species and a number of varieties. All species and varieties are fully described and most of them illustrated. The following new species are described for the first time: Triodia margineta, T. plectrachnuides, T. burkensis, T. inutilis, T. molesta, T, scariosa, T. roscida; and T. spicata. The following varieties are also new: T. pungens var. linearis, T. mitchelli var. breuibba, T. mitchelli var. pubivagina, T. irritans var. compacta, T. irritans var. laxispicata. In most cases, though not all, the varietal epithet has been used where the specimens do not seem to represent truly discontinuous populations so that specific ranking was not warranted. Maps showing the distribution of the species and varieties have been included.