Culms 1-30 cm, often profusely branching above the base, with 10-25 panicles per culm. Sheaths pilose on the margins; collars pilose; blades 1-5 cm long, 1-3 mm wide, soon disarticulating, thus many leaves on mature plants are bladeless. Panicles 0.3-1.5(3.5) cm long, 3-6(10) mm wide, 1-5 times longer than wide, sessile or almost so, mostly included in the sheaths of the upper 2 leaves. Spikelets 2.5-3.2 mm, readily disarticulating when disturbed, otherwise retained within the upper sheaths. Glumes about 3 mm, subequal; lower glumes pilose on the margins; lemmas subequal to the glumes; paleas minutely 2-veined; anthers 3, 0.5-0.9 mm. Caryopses 1.3-1.7 mm. 2n = 48.

Crypsis vaginiflora is common to abundant in clay or sandy clay soil in California, where it was first introduced in the late 1800s. It has since been found at a few locations in Washington, Idaho, and Nevada, and will probably spread to additional sites with suitable habitat in the future. It is native to Egypt and southwestern Asia.