Pseudoeriocoma Romasch., P.M.Peterson & Soreng, gen. nov.

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 : 100-101

Pseudoeriocoma Romasch., P.M.Peterson & Soreng, gen. nov.

Type.

Pseudoeriocoma eminens (Cav.) Romasch. (≡ Stipa eminens Cav.)

Diagnosis.

Pseudoeriocoma differs from Eriocoma Nutt. in having bamboo-like culms commonly with up to 13 nodes, 3-6 mm thick below, with ramified branching at the middle and upper nodes.

Description.

Plants perennial, cespitose, usually short rhizomatous from a knotty base. Culms 30-230 (often over 100) cm tall, erect or ascending, often geniculate, 3-6 mm thick and often woody and bamboo-like below with ramified and branching at the middle and upper nodes, with (2) 3-13 nodes, internodes glabrous or hairy. Leaf sheaths shorter than the internodes above to shorter or longer below, glabrous, pubescent or hirsute, sometimes ciliate on the margins and summit; collars glabrous or with a tuft of hairs; ligules 0.5-8 mm long, hyaline to membranous, apex truncate to acute or obtuse, often lacerate; blades (1.5-) 5-40 cm long, 1-4 mm wide, flat to tightly involute or convolute, glabrous or pubescent, usually scabrous. Panicles 8-45 (-55) cm long, usually rather narrow and less than 8.5 cm wide, loosely or densely flowered, branches ascending to spreading and naked near base; pedicles longer than the spikelets. Spikelets 8-15 mm long, lanceolate with one fertile floret without rachilla extension; disarticulation above the glumes; glumes (4-) 6-15 mm long, longer than the florets, subequal or unequal, hyaline to membranous, 1-7-veined, glabrous, acuminate; florets 4-7 mm long, usually fusiform; calluses 0.2-2 long, sharp, hairy; lemmas 4-7 mm long, fusiform, coriaceous, evenly hairy, the hairs 0.4-2 mm long, margins enveloping most of the palea, apex entire and awned; lemma epidermal pattern maize-like; fundamental cells squared, longitudinally compressed with straight thin sidewalls subequal to silica cells (silica bodies) or shorter, regularly alternating; cork cells absent; lemmatal awns 20-80 mm long, 2-geniculate, flexuous, the segments scabrous or pubescent; paleas 1-4.6 mm long, 1/3 to ¾ as long as the lemmas, 2-veined, veins not prolonged, hairy; anthers 2.5-4 mm long, penicillate or not, 3 in number, lodicules 2 or 3; stigmas 2. Caryopses 3-4 mm long, fusiform, pericarp adherent, hilum linear.

Distribution and habitat.

There are six species of Pseudoeriocoma occurring in southwestern North America (Mexico and USA). These species generally occur on steep rock outcrops in xerophytic vegetation; pinyon, pine, pine-oak woodlands, and spruce-fir forests; 600-3000 m ( Barkworth 2007; Valdés Reyna 2015).

Comments.

Within our preliminary molecular analyses of Pseudoeriocoma there are two clades each of P. constricta , P. eminens , and P. multinodis that require further study, and at least three species currently placed in Jarava from South America that align within Pseudoeriocoma ( Romaschenko et al. 2012, 2014; Valdés Reyna et al. 2013; Romaschenko et al. in prep.).