A revision of Trisetum (Poaceae: Pooideae Aveninae) in South America

Abstract

A taxonomic treatment of Trisetum Pers. for South America, is given. Eighteen species and six varieties of Trisetum are recognized in South America. Chile (14 species, 3 varieties) and Argentina (12 species, 5 varieties) have the greatest number of taxa in the genus. Two varieties, T. barbinode var. sclerophyllum and T. longiglume var. glabratum, are endemic to Argentina, whereas T. mattheii and T. nancaguense are known only from Chile. Trisetum andinum is endemic to Ecuador, T. macbridei is endemic to Peru, and T. foliosum is endemic to Venezuela. A total of four species are found in Ecuador and Peru, and there are two species in Venezuela and Colombia. The following new species are described and illustrated: Trisetum mattheii Finot and T. nancaguense Finot, from Chile, and T. pyramidatum Louis-Marie ex Finot, from Chile and Argentina. The following two new combinations are made: T. barbinode var. sclerophyllum (Hack. ex Stuck.) Finot and T. spicatum var. cumingii (Nees ex Steud.) Finot. A key for distinguishing the species and varieties of Trisetum in South America is given. The names Koeleria cumingii Nees ex Steud., Trisetum sect. Anaulacoa Louis-Marie, Trisetum sect. Aulacoa Louis-Marie, Trisetum subg. Heterolytrum Louis-Marie, Trisetum subg. Isolytrum Louis-Marie, Trisetum suhsect. Koeleriformia Louis-Marie, Trisetum subsect. Sphenopholidea Louis-Marie, Trisetum malacophyllum Steud., Trisetum variabile E. Desv., and Trisetum variabile var. virescens E. Desv. are lectotypified.