Achnatherum

Achnatherum
Achnatherum parishii
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Poales
Family: Poaceae
Subfamily: Pooideae
Supertribe: Stipodae
Tribe: Stipeae
Genus: Achnatherum
P. Beauv.
Species

about 20 species, see text

Synonyms
  • Aristella Bertol.
  • Lasiagrostis Link, nom. superfl.

Achnatherum is a genus of flowering plants in the grass family, Poaceae. It includes 20 species of needlegrass native to temperate Eurasia and North Africa. Several needlegrass species have been switched between Achnatherum and genus Stipa; taxonomy between the two closely related genera is still uncertain. In 2019 Peterson et al. reorganized the genera in tribe Stipeae based on molecular DNA studies, and placed the species from the Americas into other genera.

Description

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.

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):

Genus … Achnatherum, nov.; Plate VI, figure VII

Species formerly referred to Calamagrostis (Adanson, Roth, Decandolle); to Agrostis (Linnaeus, Jussieu, etc.); and to Arundo (Koeler). Panicle compound, loose; glumes longer than the membranous paleas; lower palea nearly notched at the apex, bearing a twisted, non-jointed awn; upper palea entire, acute; lodicules lanceolate, entire, glabrous; style short, divided into two parts; stigmas villous; seed furrowed. Species included: Agrostis calamagrostis L.; A. miliacea; A. tenuifolia; A. sobolifera; A. conspicua; A. bromoides? (Persoon, Willdenow); Arundo lanceolata Koeler.

Observation: This genus appears closely allied to Calamagrostis; but differs in bearing an awn; having the lower palea simply notched without bristle; and the upper palea entire.

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

Formerly placed here

Species previously included in Achnatherum:

  • Amelichloa brachychaeta (Godr.) Arriaga & Barkworth (as Achnatherum brachychaetum (Godr.) Barkworth) - punagrass
  • Amelichloa caudata (Trin.) Arriaga & Barkworth (as Achnatherum caudatum (Trin.) S.L.W.Jacobs & J.Everett) - Chilean ricegrass
  • Amelichloa clandestina (Hack.) Arriaga & Barkworth (as Achnatherum clandestinum (Hack.) Barkworth) - Mexican ricegrass
  • Barkworthia stillmanii (Bol.) Romasch., P.M.Peterson & Soreng (as Achnatherum stillmanii (Bol.) Barkworth) - Stillman's needlegrass
  • Eriocoma arida (M.E.Jones) Romasch. (as Achnatherum aridum (M.E.Jones) Barkworth) - Mormon needlegrass
  • Eriocoma × bloomeri (Bol.) Romasch. (as Achnatherum × bloomeri (Boland.) Barkworth) - Bloomer's ricegrass
  • Eriocoma contracta (B.L.Johnson) Romasch. (as Achnatherum contractum (B.L. Johnson) Barkworth) - contracted ricegrass
  • Eriocoma coronata (Thurb.) Romasch. (as Achnatherum coronatum (Thurb.) Barkworth) - crested needlegrass
  • Eriocoma curvifolia (Swallen) Romasch. (as Achnatherum curvifolium (Swallen) Barkworth) - Guadalupe ricegrass
  • Eriocoma hymenoides (Roem. & Schult.) Rydb. (as Achnatherum hymenoides (Roem. & Schult.) Barkworth) - Indian ricegrass
  • Eriocoma hendersonii (Vasey) Romasch. (as Achnatherum hendersonii (Vasey) Barkworth) - Henderson's needlegrass
  • Eriocoma latiglumis (Swallen) Romasch. (as Achnatherum latiglume (Swallen) Barkworth) - wide-glumed needlegrass
  • Eriocoma lemmonii (Vasey) Romasch. (Achnatherum lemmonii (Vasey) Barkworth) - Lemmon's needlegrass
  • Eriocoma lettermanii (Vasey) Romasch. (as Achnatherum lettermanii (Vasey) Barkworth) - Letterman's needlegrass
  • Eriocoma lobata (Swallen) Romasch. (as Achnatherum lobatum (Swallen) Barkworth) - lobed needlegrass
  • Eriocoma nelsonii (Scribn.) Romasch. (as Achnatherum nelsonii (Scribn.) Barkworth) - Nelson's needlegrass, Dore's needlegrass
  • Eriocoma nevadensis (B.L.Johnson) Romasch. (as Achnatherum nevadense (B.L. Johnson) Barkworth) - Nevada needlegrass
  • Eriocoma occidentalis (Thurb. ex S.Watson) Romasch. (as Achnatherum occidentale (Thurb.) Barkworth) - western needlegrass
  • Eriocoma parishii (Vasey) Romasch. (as Achnatherum parishii (Vasey) Barkworth) - Parish's needlegrass
  • Eriocoma perplexa (Hoge & Barkworth) Romasch. (as Achnatherum perplexum Hoge & Barkworth) - perplexing needlegrass
  • Eriocoma pinetorum (M.E.Jones) Romasch. (as Achnatherum pinetorum (M.E. Jones) Barkworth) - pinewoods needlegrass
  • Eriocoma richardsonii (Link) Romasch. (as Achnatherum richardsonii (Link) Barkworth) - Richardson's needlegrass
  • Eriocoma robusta (Vasey) Romasch. (as Achnatherum robustum (Vasey) Barkworth) - sleepygrass
  • Eriocoma scribneri (Vasey) Romasch. (as Achnatherum scribneri (Vasey) Barkworth) - Scribner needlegrass
  • Eriocoma thurberiana (Piper) Romasch. (as Achnatherum thurberianum (Piper) Barkworth) - Thurber's needlegrass
  • Eriocoma swallenii (C.L.Hitchc. & Spellenb.) Romasch. (as Achnatherum swallenii (C.L. Hitchc. & Spellenb.) Barkworth) - Swallen's needlegrass
  • Eriocoma webberi Thurb. (as Achnatherum webberi (Thurb.) Barkworth) - Webber needlegrass
  • Neotrinia splendens (Trin.) M.Nobis, P.D.Gudkova & A.Nowak (as Achnatherum splendens (Trin.) Nevsky)
  • Pappostipa speciosa (Trin. & Rupr.) Romasch. (as Achnatherum speciosum Trin. & Rupr.) - desert needlegrass
  • Pentameris pallida (Thunb.) Galley & H.P.Linder (as Achnatherum capense (L.) P.Beauv.)
  • Ptilagrostis duthiei (Hook.f.) M.Nobis & P.D.Gudkova (as Achnatherum duthiei (Hook.f.) P.C.Kuo & S.L.Lu)
  • Pseudoeriocoma acuta (Swallen) Romasch. (as Achnatherum acutum (Swallen) Valdés-Reyna & Barkworth)
  • Pseudoeriocoma editorum (E.Fourn.) Romasch. (as Achnatherum editorum (E.Fourn.) Valdés-Reyna & Barkworth)
  • Pseudoeriocoma eminens (Cav.) Romasch. (as Achnatherum eminens (Cav.) Barkworth) - southwestern needlegrass
  • Stipellula parviflora (Desf.) Röser & Hamasha (as Achnatherum parviflorum Desf.) M.Nobis - Small-flowered needlegrass
  • Thorneochloa diegoensis (Swallen) Romasch. (as Achnatherum diegoense (Swallen) Barkworth) - San Diego needlegrass
  • Timouria conferta (Poir.) Sennikov (as Achnatherum caragana (Trin.) Nevski)

References

  1. 1 2 3 4 "Achnatherum P.Beauv". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 16 December 2024.
  2. 1 2 Peterson PM, Romaschenko K, Soreng RJ, Valdés Reyna J (2019) 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. PhytoKeys 126: 89-125. https://doi.org/10.3897/phytokeys.126.34096
  3. ↑ Tutin, T. G.; Heywood, V. H.; Burges, N. A.; Moore, D. M.; Valentine, D. H.; Walters, S. M.; Webb, D. A., eds. (1980). "Achnatherum". Flora Europaea. Volume 5: Alismataceae to Orchidaceae. Cambridge University Press. p. 252.
  4. 1 2 Palisot de Beauvois, Ambroise-Marie-François-Joseph (1812). Essai d'une nouvelle agrostographie, ou, Nouveaux genres des graminées : avec figures représentant les caractères de tous les genres. Chez l'auteur. pp. 19–20.
  5. ↑ Bertoloni, A. (1834). Flora Italica. Vol. 1. Bologna: Tipografia Sassi. p. 690.
  6. ↑ Link, H.F. (1827). Hortus Regius Botanicus Berolinensis. Berlin: Haude et Spener.
  7. ↑ "Achnatherum". World Flora Online. Retrieved 16 December 2025.
  8. ↑ Clayton, W.D.; Renvoize, S.A. (1986). Genera Graminum: Grasses of the World. Kew Bulletin Additional Series. Vol. 13. Royal Botanic Gardens, Kew.