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 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.
"decumbent" is not a number.