Plants annual; tufted or culms solitary. Culms 7-70 cm, erect to decumbent. Leaves cauline; sheaths open; auricles vestigal or absent; ligules membranous; blades flat. Inflorescences panicles, contracted or spiciform; branches appressed to ascending. Spikelets laterally compressed, solitary, with 1 bisexual floret; rachillas prolonged as bristles or absent; disarticulation above the glumes. Glumes unequal, exceeding the florets, 1-veined, basally subcoriaceous and gibbously swollen, distally membranous, narrow, acuminate to attenuate, unawned; calluses short, blunt, glabrous; lemmas membranous, pubescent or glabrous, 5-veined, lateral veins usually faint, apices more or less truncate and denticulate, unawned or awned in the upper 1/3, awns shorter or longer than the lemmas, geniculate, unawned and awned lemmas present in the same panicle; paleas subequal to the lemmas, hyaline, 2-veined, bifid; lodicules2, membranous, glabrous, entire, unlobed; anthers 3; ovaries glabrous. Caryopses slightly adhering to the lemmas and/or paleas, hila short. x = 7. Name from the Greek gastridion, small pouch, alluding to the gibbously swollen glumes.

Gastridium is a genus of two species, native to Europe and North Africa eastwards to Iran. They grow in grassy or disturbed sites.

1.   Gastridium phleoides (Nees & Meyen) C.E. Hubb.
Nit Grass

Plants tufted or solitary. Culms 7-70 cm; nodes 3-5, glabrous, darkened. Sheaths 0.6-10.5 cm, smooth or scabridulous and minutely papillose; ligules 1-7 mm, veined, erose to lacerate, scabridulous and minutely papillose; blades (0.8)1.5-20 cm long, (0.4)1.5-6 mm wide, antrorsely scabridulous, glabrous. Panicles (1.1)2-16.5 cm long, (1.5)3-37 mm wide; rachises glabrous; branches to 3.4 cm, appressed to ascending, antrorsely scabridulous, pedicels with enlarged apices. Rachilla extensions 0.3-0.6 mm, densely pubescent. Glumes antrorsely scabridulous and minutely papillose below, almost scabrous above, margins hyaline; lower glumes 3-7 mm; upper glumes 2.7-5.5 mm; lemmas 1-1.5 mm, appressed pubescent, unawned or awned, awns to 6 mm, column twisted; paleas 1-1.3 mm, glabrous; anthers 0.5-0.9 mm, yellow-orange or purple. Caryopses 0.8-1 mm long, 0.4-0.5 mm wide, glabrous. 2n = 14.

Native to southwest Asia and northeast Africa, Gastridium phleoides now grows in Australia, South Africa, North America, and South America on dry, often disturbed areas. In the Flora region it is established in Oregon and California; it has also been collected in Arizona, western Texas (US 843557, Texas, 1884, Nealley s.n.), Massachusetts, and South Carolina.

Gastridium phleoides has been mistakenly placed in G. ventricosum (Gouan) Schinz & Thell. in North America, but it differs in having densely pubescent lemmas and well-developed, densely pubescent rachilla extensions.