Achnatherum

The genus Achnatherum (syn. Lasiagrostis) is closely related to Stipa but can be distinguished by several morphological traits. Unlike Stipa, the young leaves of Achnatherum are convolute (rolled inward) rather than folded. Its spikelets are laterally compressed, and the lemma bears spreading hairs up to 4 mm long near the base. The awn is either straight or gently curved, but never abruptly bent (geniculate) or twisted below, which sets it apart from the characteristic awns of Stipa.{{cite book| editor-last = Tutin| editor-first = T. G. ==Taxonomy==

Original Description The genus Achnatherum was first described by Palisot de Beauvois in 1812 in his ''Essai d'une Nouvelle Agrostographie''. The protologue reads (translated): Botanical history The genus Achnatherum was first described by Palisot de Beauvois in Essai d'une Nouvelle Agrostographie (1812), where it was distinguished from allied genera such as Agrostis and Calamagrostis by its awned lemmas and distinctive palea morphology. In 1834, Bertoloni introduced the segregate genus Aristella in Flora Italica, describing species such as Aristella bromoides. Other authors also used names like Lasiagrostis Link (1827) for similar taxa. Modern taxonomic treatments, including Plants of the World Online and World Flora Online, regard Aristella and Lasiagrostis as heterotypic synonyms of Achnatherum. During the 19th and 20th centuries, species now placed in Achnatherum were variously assigned to Stipa, Agrostis, and Arundo, reflecting uncertainty in the delimitation of tribe Stipeae. Recent molecular phylogenetic studies have clarified relationships within the tribe, supporting the recognition of Achnatherum as a distinct lineage and consolidating former segregate genera under this name. ==Species==

19 species are accepted by Plants of the World Online as of December 2025: Unplaced species • Achnatherum roshevitzii (unplaced) - Roshevich's achnatherum Formerly placed here Species previously included in Achnatherum: • Amelichloa brachychaeta (as Achnatherum brachychaetum ) - punagrass • Amelichloa caudata (as Achnatherum caudatum ) - Chilean ricegrass • Amelichloa clandestina (as Achnatherum clandestinum ) - Mexican ricegrass • Barkworthia stillmanii (as Achnatherum stillmanii ) - Stillman's needlegrass • Eriocoma arida (as Achnatherum aridum ) - Mormon needlegrass • Eriocoma × bloomeri (as Achnatherum × bloomeri ) - Bloomer's ricegrass • Eriocoma contracta (as Achnatherum contractum ) - contracted ricegrass • Eriocoma coronata (as Achnatherum coronatum ) - crested needlegrass • Eriocoma curvifolia (as Achnatherum curvifolium ) - Guadalupe ricegrass • Eriocoma hymenoides (as Achnatherum hymenoides ) - Indian ricegrass • Eriocoma hendersonii (as Achnatherum hendersonii ) - Henderson's needlegrass • Eriocoma latiglumis (as Achnatherum latiglume ) - wide-glumed needlegrass • Eriocoma lemmonii (Achnatherum lemmonii ) - Lemmon's needlegrass • Eriocoma lettermanii (as Achnatherum lettermanii ) - Letterman's needlegrass • Eriocoma lobata (as Achnatherum lobatum ) - lobed needlegrass • Eriocoma nelsonii (as Achnatherum nelsonii ) - Nelson's needlegrass, Dore's needlegrass • Eriocoma nevadensis (as Achnatherum nevadense ) - Nevada needlegrass • Eriocoma occidentalis (as Achnatherum occidentale ) - western needlegrass • Eriocoma parishii (as Achnatherum parishii ) - Parish's needlegrass • Eriocoma perplexa (as Achnatherum perplexum ) - perplexing needlegrass • Eriocoma pinetorum (as Achnatherum pinetorum ) - pinewoods needlegrass • Eriocoma richardsonii (as Achnatherum richardsonii ) - Richardson's needlegrass • Eriocoma robusta (as Achnatherum robustum ) - sleepygrass • Eriocoma scribneri (as Achnatherum scribneri ) - Scribner needlegrass • Eriocoma thurberiana (as Achnatherum thurberianum ) - Thurber's needlegrass • Eriocoma swallenii (as Achnatherum swallenii ) - Swallen's needlegrass • Eriocoma webberi (as Achnatherum webberi ) - Webber needlegrass • Neotrinia splendens (Trin.) M.Nobis, P.D.Gudkova & A.Nowak (as Achnatherum splendens (Trin.) Nevsky) • Pappostipa speciosa (as Achnatherum speciosum ) - desert needlegrass • Pentameris pallida (as Achnatherum capense ) • Ptilagrostis duthiei (as Achnatherum duthiei ) • Pseudoeriocoma acuta (as Achnatherum acutum ) • Pseudoeriocoma editorum (as Achnatherum editorum ) • Pseudoeriocoma eminens (as Achnatherum eminens ) - southwestern needlegrass • Stipellula parviflora (as Achnatherum parviflorum - Small-flowered needlegrass • Thorneochloa diegoensis (as Achnatherum diegoense ) - San Diego needlegrass • Timouria conferta (as Achnatherum caragana ) ==References==