Gynomonoecious. Annuals (rarely surviving for a second season); tufted, infrequently short stooling, tufts generally small, bases usually narrow, green to light green; tillers intravaginal (each subtended by a single 2-keeled, longitudinally split prophyll over 0.5 cm long), without cataphyllous shoots, most shoots eventually flowering. Culms 2--20(--45) cm tall, spreading to erect, sometimes geniculate, leafy, slender, terete, smooth; usually 1 nodes. Leaves; leaf sheaths terete or weakly compressed, bulb absent, smooth, glabrous; butt-sheaths papery, smooth glabrous; flag-leaf sheath 1--6 cm long, margins fused ca. 33% the length; throats and collars smooth, glabrous; ligules 0.5--3(--5) mm long, decurrent, abaxially smooth, glabrous, apices obtuse to truncate; blades 1--10 cm long, 1--3(--6) mm wide, flat or weakly folded, thin, soft. smooth, margins usually slightly scabrous, broadly prow-tipped; blades all about equal in length, flag-leaf blades well developed. Panicles 1--7(--10) cm long, 1.2--1.6 x long as wide, erect, open, pyramidal to rhomboid, moderately congested to sparse; rachis with 1--2(--3) branches per node; primary branches ascending to spreading or reflexed, straight, terete or sulcate, smooth; lateral pedicels less than 1/3 the spikelet in length, smooth; longest branches 2--4(--5) cm, spikelets crowded or loosely arranged. Spikelets 3--5 mm long, ovate, laterally compressed, not bulbiferous; florets 2--6, proximal hermaphroditic, distal often pistillate; rachilla internodes terete, smooth, glabrous, more or less concealed or exposed, distal internode less than 1/2(--3/4) length of distal lemma; glumes unequal, smooth, distinctly keeled, keels smooth, apex acuminate to acute or obtuse, sharp pointed or slightly blunt; lower glumes 1--2.2 mm long, 1-veined, narrowly lanceolate, often slightly sickle shaped, or subulate, apex acute; upper glumes 1.5--2.5 mm long, shorter than or subequaling lowest lemma,3-veined, lanceolate to oblanceolate, apex obtuse to acute; calluses glabrous; lemmas 2.2--3.3(--4) mm long, broadly lanceolate, green to light green, sometimes slightly violaceous, distinctly keeled, smooth throughout, keels, marginal, and usually intermediate veins moderately to densely crisply puberulent to long villous, rarely glabrous throughout, between veins glabrous, intermediate veins prominent, margins and edges smooth, apices obtuse to acute; paleas keels smooth, short to long villous, rarely glabrous over the keels. Flowers cleistogamous to chasmogamous; lodicules 0.45--0.5 mm long, broadly lanceolate to ovate, with 1 (rarely 2) short lateral lobe(s); anthers 0.6--1.1 mm long, oblong prior to dehiscence, often vestigial in distal flowers of a spikelet; caryopses 1.6--2.3 mm long, elliptical in side-view, subcylindrical in cross-section, light reddish-brown, sulcus almost flat, hilum 0.15 mm long, oval, grain free or adherent to the palea. 2n = 28. Genotype: Mm (RJS 2016)