Revision of Poa L. (Poaceae, Pooideae, Poeae, Poinae) in Mexico: new records, re-evaluation of P. ruprechtii, and two new species, P. palmeri and P. wendtii

A revision and key to the 23 species and eight subspecies of Poa (including Dissanthelium) known to occur in Mexico is provided. All voucher specimens seen are cited for accepted taxa, except Poa annua for which one voucher per state is provided. Taxa not previously known from, or poorly understood in, Mexico are discussed.Poa palmerisp. nov. is endemic to forested slopes of the Sierra Madre Oriental, and we distinguished it from Poa ruprechtii s.s., a species of central Mexico that is here emended to include Poa sharpii (syn. nov.). Poa wendtiisp. nov. is described from the Sierra Santa Rosa in northern Coahuila. Poa tacanae is placed in synonymy in Poa seleri. Poa gymnantha and Poa occidentalis are newly reported for Mexico, and material historically identified as Poa villaroelii areplaced in Poa chamaeclinos.The genus Dissanthelium is considered to belong within Poa, and the Mexican taxa, Dissanthelium calycina subsp. mathewsii and Dissanthelium californicum, are treated as Poa calycina var. mathewsii and Poa thomasii, respectively. Poa subsect. Papillopoasubsect. nov. is erected for Poa mulleri. Lectotypes are designated for Poa conglomerata and Poa seleri.