Agrostis meyenii Trin. (Poaceae, Agrostidinae): first records from Peru, including taxonomic notes and an identification key

The grass Agrostis meyenii Trin. (Poaceae, Agrostidinae) is newly recorded from Peru and is found in high-Andean puna grasslands of the departments of Ancash, Ayacucho, and Huánuco, marking the northernmost known limit of this species. A revised species description, images, taxonomic notes, and a key are also presented to differentiate A. meyenii from similar species in Peru with congested, spike-like panicles and absent or reduced (measuring less than ½ the length of the lemma) paleas (i.e., A. breviculmis Hitchc., A. foliata Hook.f., and A. tolucensis Kunth).