A key to the North American genera of Stipeae (Poaceae, Pooideae) with descriptions and taxonomic names for species of Eriocoma, Neotrinia, Oloptum, and five new genera: Barkworthia, ×Eriosella, Pseudoeriocoma, Ptilagrostiella, and Thorneochloa

Based on earlier molecular DNA studies we recognize 14 native Stipeae genera and one intergeneric hybrid in North America. We provide descriptions, new combinations, and 10 illustrations for species of Barkworthiagen. nov., Eriocoma, Neotrinia, Oloptum, Pseudoeriocomagen. nov., Ptilagrostiellagen. nov., Thorneochloagen. nov., and ×Eriosellanothogen. nov. The following 40 new combinations are made: Barkworthiastillmanii, Eriocomaalta, E.arida, E.arnowiae, E.bloomeri, E.bracteata, E.contracta, E.coronata, E.curvifolia, E.hendersonii, E.latiglumis, E.lemmonii, E.lemmoniissp.pubescens, E.lettermanii, E.lobata, E.nelsonii, E.nelsoniissp.dorei, E.nevadensis, E.occidentalis, E.occidentalisssp.californica, E.occidentalisssp.pubescens, E.parishii, E.parishiissp.depaupertata, E.perplexa, E.pinetorum, E.richardsonii, E.robusta, E.scribneri, E.swallenii, E.thurberiana, E.wallowaensis, ×Eriosellacaduca, Pseudoeriocomaacuta, P.constricta, P.editorum, P.eminens, P.hirticulmis, P.multinodis, Ptilagrostiellakingii, and Thorneochloadiegoensis. A key to the native and introduced genera of North American Stipeae, and an overview of the tribe in North America and worldwide are given. Lectotypes are designated for Eriocomacuspidata Nutt., Fendleriarhynchelytroides Steud., Stipabloomeri Bol., Stipacoronata Thurb., Stipamembranacea Pursh, Stipamormonum Mez, Stiparichardsonii Link, and Stipawilliamsii Scribn. Achnatherum s.s. and Piptatherum s.s. are now restricted to Eurasia and the Mediterranean/Asia, respectively.