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, xEriosella, 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 Barkworthia gen. nov., Eriocoma, Neotrinia, Oloptum, Pseudoeriocoma gen. nov., Ptilagrostiella gen. nov., Thorneochloa gen. nov., and xEriosella nothogen. nov. The following 40 new combinations are made: Barkworthia stillmanii, Eriocoma alta, E. arida, E. arnowiae, E. bloomeri, E. bracteata, E. contracta, E. coronata, E. curvifolia, E. hendersonii, E. latiglumis, E. lemmonii, E. lemmonii ssp. pubescens, E. lettermanii, E. lobata, E. nelsonii, E. nelsonii ssp. dorei, E. nevadensis, E. occidentalis, E. occidentalis ssp. californica, E. occidentalis ssp. pubescens, E. parishii, E. parishii ssp. depaupertata, E. perplexa, E. pinetorum, E. richardsonii, E. robusta, E. scribneri, E. swallenii, E. thurberiana, E. wallowaensis, xEriosella caduca, Pseudoeriocoma acuta, P. constricta, P. editorum, P. eminens, P. hirticulmis, P. multinodis, Ptilagrostiella kingii, and Thorneochloa diegoensis. 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 Eriocoma cuspidata Nutt., Fendleria rhynchelytroides Steud., Stipa bloomeri Bol., Stipa coronata Thurb., Stipa membranacea Pursh, Stipa mormonum Mez, Stipa richardsonii Link, and Stipa williamsii Scribn. Achnatherum s.s. and Piptatherum s.s. are now restricted to Eurasia and the Mediterranean/Asia, respectively.