Contribution to the study of the genus Rhynchospora (Cyperaceae) V. Section Longirostres in Austral America

Abstract

The section Longirostres, belonging of Rhynchospora subgen. Haplostylis (Cyperaceae), comprises 19 species, mostly extended in warm temperate and tropical regions of America, 2 species are cosmopolitan and R. hookeri grows in Malasia, India and Africa. Rhynchospora careyana, R. corniculata,
R. inundata and R. macrostachya are present in North America and the Antilles. Ten species, 2 subspecies and 5 varieties from Austral America, from a total of 13 species, were considered in the present treatment: R. corymbosa, with its varieties: corymbosa, bonariensis, and chacoensis; two new combinations, and stat. nov. are proposed in R. corymbosa: var. angustirostris (Barros) Guagl. and var. legrandii (Kük. ex Barros) Guagl.; other species treated are: R. amazonica and its subsp. guianensis, R. asperula (previously included in R. corymbosa), R. gigantea, R. scutellata, R. trispicata, R. stenocarpa and the cosmopolitan R. triflora. Rhynchospora latibracteata Guagl., is a new species from Brazil and Uruguay; a new name is proposed, R. pedersenii Guagl. The taxa are described and illustrated. Maps of geographic distribution, references to the habitat and keys for identification of American taxa are also given. Rhynchospora sampaioana is excluded from section Longirostres.