Eriocoma Nutt., Gen. N. Amer. Pl. 1: 40. 1818

Peterson, Paul M., Romaschenko, Konstantin, Soreng, Robert J. & Reyna, Jesus Valdes, 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, x Eriosella, Pseudoeriocoma, Ptilagrostiella, and Thorneochloa, PhytoKeys 126, pp. 89-125 : 93

Eriocoma Nutt., Gen. N. Amer. Pl. 1: 40. 1818

Eriocoma = Fendleria Steud., Syn. Pl. Glumac. 1: 419. 1854. Type: Fendleria rhynchelytroides Steud. (= Eriocoma hymenoides ).

Type.

Eriocoma hymenoides (Roem. & Schult.) Rydb. (≡ Stipa hymenoides Roem. & Schult.).

Description.

Plants perennial, sometimes short rhizomatous, tightly to loosely cespitose. Culms 10-230 cm tall, erect, unbranched above, nodes glabrous or pubescent, nodes 2-4 (5). Leaf sheaths glabrous, pubescent or pilose, glabrous or distally ciliate; collars glabrous or with a tufts of hairs; ligules 0.1-10 mm long, hyaline to membranous, apex truncate, obtuse, acute or narrowly acute; blades 0.1-7 mm wide, flat, convolute or involute, smooth, scabrous, glabrous or hairy. Panicles 2.5-60 cm long, up to 15 cm wide, usually contracted, sometimes open with divergent branches; branches straight, sometimes flexuous. Spikelets 5-21 mm long, usually lanceolate, sometimes obovoid, subterete, rarely laterally compressed, with one fertile floret without rachilla extension, disarticulation above the glumes; glumes 5-21 mm long, longer than the florets, unawned, 1(3)-veined, apex usually acuminate, sometimes acute; florets 2.5-10 mm long, usually fusiform, sometimes obovoid; calluses 0.3-2 mm long, blunt, sharp, or acute, hairy; lemmas usually coriaceous, sometimes indurate, usually evenly hairy, sometimes glabrous, or distally or with longer or shorter hairs than the body, apex usually entire or 2-lobed with lobes less than 2.1 mm long; lemma epidermal pattern maize-like; fundamental cells square with roundish corners and straight sidewalls subequal to silica cells or shorter, often regularly alternating; silica bodies square-cornered or sometimes rounded without contractions; cork cells scarce to absent; lemmatal awns 3-80 mm long, 1 or 2-geniculate; paleas ¼ to as long or longer than the lemma, 2-veined, usually hairy, sometimes glabrous, veins usually not prolonged, but if prolonged then not more than 0.3 mm long; anthers 1-5 mm long, usually penicillate, 3 in number; lodicules 2 or 3; stigmas 2. Caryopses fusiform, pericarp adherent, hilum linear.

Distribution.

There are 27 species of Eriocoma , all occurring in western North America (Canada, Mexico, and the USA) and only E. hymenoides extends its range into northeastern USA ( Gleason and Cronquist 1991).

Comments.

Within our earlier and unpublished molecular analyses of Eriocoma there are three separate clades of E. lobata and one undescribed species ( Romaschenko et al. 2012, 2014; Valdés Reyna et al. 2013; Romaschenko et al. in prep.). Species now included in Eriocoma were placed in Oryzopsis or Stipa ( Hitchcock 1951), in Stipa ( Espejo Serna et al. 2000), in Achnatherum ( Barkworth 2007; Dávila et al. 2018), or in Achnatherum or Eriocoma ( Sánchez-Ken 2018).