Sporobolus vaginiflorus is an annual C4 grass (Hilty 2006), wispy, tufted, shallow-rooted, 20-50 cm, stems thin, wiry; sheaths 1.5-5 cm long, often long-hairy at top, ligule tiny or none.
Leaves alternate, 0.1-0.2 cm wide, becoming short near top of stems.
Flower spikelets 1-flowered, 0.4-0.6 cm long, papery, whitish, glumes sub-equal ca 3-4.5 mm, lemmas 3-5 mm, finely hairy, 1-veined, tip long-pointed, palea often longer than lemma, finely hairy, tip pointed; inflorescence a series of small enclosed condensed panicles along the stem, 1-5 cm, narrow, most enclosed within leaf sheaths, 2 inflorescence types: 1) inside sheath, flowers stay closed, self-pollinating, 2) terminal inflorescence with open flowers, out-crossing. Seeds of self-fertilized flowers stay on dead plant through winter germinate in a mass in spring (Cheplick 1993); blooms and fruits late Aug.-Oct.
Wetland status: UPL.
Frequency in NYC: Very infrequent.
Habitat: Weedy on dry, open habitats, roadsides, lots, fill, landfills usually on dry, infertile soil.