Revision and cladistic analysis of Steinchisma (Poaceae: Panicoideae: Paniceae)

The genus Steinchisma Raf. (Poaceae: Panicoideae: Paniceae) is revised. Six species are treated in this work, in which exomorphological and anatomical characters are analyzed cladistically. Steinchisma comprises perennial species that grow in open areas or near borders of rivers and streams. The plants possess membranous ligules, leaves lanceolate to filiform, inflorescences law and diffuse to contracted, with spikelets solitary on short or long pedicels; ellipsoid spikelets, glabrous, with the lower glume 1/3 to 1/2 the length of the spikelet, upper glume and lower lemma subequal, lower palea as long as the upper anthecium, expanded at maturity, lower flower present, with three stamens, or absent; indurate upper anthecium; and a basic chromosome number of x = 10. A similar anatomical pattern, intermediate between Kranz and non-Kranz species, was found in all species. A cladistic analysis of Steinchisma was conducted in order to test its monophyly, and relationships with the subgenera of Panicum. A key to the species is provided, as well as an anatomical description of the genus and photomicrographs of two species; morphological descriptions, illustrations, and distribution maps are presented for all six species of Steinchisma. A new combination is made, Steinchisma stenophylla (Hack.) Zuloaga & Morrone.