Ptilagrostiella 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 : 102-103

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

Type.

Ptilagrostiella kingii (Bol.) Romasch. (≡ Stipa kingii Bol.).

Diagnosis.

Ptilagrostiella differs from Piptatheropsis Romasch., P.M. Peterson & Soreng in having glumes without veins with obtuse apices, a sharp callus, and laterally compressed florets with lemma margins overlapping most of the palea at maturity; and differs from Ptilagrostis Griseb. in having a sharp-pointed callus and lemmatal awns with very short hairs.

Description.

Plants perennial, cespitose, not rhizomatous with intravaginal branching. Culms 15-40 cm tall, 0.4-0.8 mm in diameter, erect, glabrous, not branching above. Leaf sheaths open, glabrous to scaberulous; ligules 1-2.5 mm long, membranous, apex obtuse to acute; blades 3-15 cm long, 0.3-0.5 mm wide, convolute, filiform, flexuous. Panicles 4-10 cm long, loosely contracted; branches ascending and usually appressed. Spikelets 3-4.5 mm long, lanceolate with one fertile floret without rachilla extension; disarticulation above the glumes; glumes 3-4.5 mm long, usually longer than the florets, hyaline, without veins, apex obtuse; florets 2.8-4.2 mm long, laterally compressed; calluses 0.3-0.7 mm long, sharp, hairy; lemmas 2.8-4.2 mm long, membranous to chartaceous, evenly pubescent throughout, the hairs 0.3-0.5 mm long, margins overlapping most of the palea at maturity, apex 2-lobed, the lobes 0.1-0.4 mm long, awned; lemma epidermal pattern saw-like; fundamental cells of variable length with sinuous sidewalls 2-8 times longer than silica cells irregularly alternating; silica bodies elongated-rectangular, sometimes paired with square-shaped cork cells; lemmatal awns 10-14 mm long, strigillose in lower part; 1- or 2-geniculate, persistent; paleas 2.6-3.2 mm long, shorter to about as long as the lemma, chartaceous, 2-veined; stamens 3, anthers 0.5-1.5 mm long, penicillate; lodicules 3, membranous; stigmas 2; ovary glabrous. Caryopses 1.5-2.3 mm long, fusiform, pericarp adherent. Chromosome number 2 n = 22 ( Johnson 1945).