Oloptum Roeser & H.R. Hamasha, Pl. Syst. Evol. 298: 365. 2012

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 : 98

Oloptum Roeser & H.R. Hamasha, Pl. Syst. Evol. 298: 365. 2012

Type.

Oloptum miliaceum (L.) Röser & H.R. Hamasha (≡ Agrostis miliacea L.).

Description.

Plants perennial, loosely cespitose, not rhizomatous with extravaginal branching. Culms 50-150 cm tall, erect or geniculate ascending, glabrous, often branching at lower cauline nodes. Leaf sheaths glabrous, persistent, margins hyaline above, smooth; ligules membranous; basal ligules 0.5-1.5 mm long, apex truncate; upper ligules 1.5-4 mm long, apex obtuse to acute; blades (5-) 10-30 cm long, 2-10 mm wide, flat, glabrous, smooth or scaberulous, margins scaberulous, apex attenuate. Panicles 10-40 cm long, 3-15 (-18) cm wide, ovate, open; lower branches 3-8 cm long, ascending and spreading, whorled, 3-8 at a node or with 15-30 or more at the lowest node, these often with sterile spikelets. Spikelets 2.5-3.5 mm long, elliptic, dorsally compressed with one fertile floret without rachilla extension; disarticulation above the glumes; glumes subequal, longer than the florets, 3-veined without transverse veinlets, membranous, apices acuminate; florets 2-2.5 mm long, chartaceous; calluses about 0.3 mm long, with non-grooved circular disarticulation scar, glabrous; lemmas with narrow open borders, central vein not grooved, apex awned, the awns 3-5 mm long, flexuous, cauducous; lemma epidermal pattern maize-like; fundamental cells elongated with straight thin sidewalls 3-7 times longer than silica cells, irregularly alternating; silica bodies round; cork cells crescent-shaped scarce to absent; paleas about as long as the lemma, coriaceous, 2-veined; stamens 3, anthers 2-2.5 mm long, penicillate; lodicules 3; stigmas 2; ovary glabrous. Caryopses 1.5-1.7 mm long, fusiform, pericarp adherent, hilum linear about ½ as long as the caryopsis. Chromosome number 2 n = 24 ( Faruqi et al. 1987; Devesa et al. 1991; Luque and Lifante 1991; Verlaque et al. 1997).