Aristida dichotoma is an annual C4 grass (Iverson et al. undated), 20-40 cm tall; stems tufted, branched from base, zigzaged, wispy, pale gray-green to sometimes reddish; leaf sheaths becoming distended; ligule a minute fringe of hairs.
Leaves alternate, 8–15 cm long; 0.1–0.2 cm wide (Clayton et al. 2002+), thread-like, usually in-rolled, basal leaves much shorter than those of flowering stems, old basal leaves becoming flat, curling.
Flower spikelets 1-flowered, 0.4-1 cm long, linear; glumes membranous, almost equal, 0.5-1 cm long, lemma leathery, 0.5-0.9 cm long, base hairy (callus bearded), tip 3-awned, central awn 0.3-1 cm long, coiled at base, divergent, tip horizontal to flower stem, lateral awns straight, 0.1-0.3 cm long; terminal inflorescence very thin, spike-like, 3-8 cm long, usually branched but closely contracted, lateral inflorescences hidden in leaf sheaths; blooms and fruits Aug.-Oct.
Fruit dry, 1-seeded, lemma remains closely wrapped around the palea and grain, breaking off the inflorescence above the glumes, which remain on the dry plant.
Wetland status: NL.
Frequency in NYC: Infrequent.
Habitat: Dry, sterile soil, fill, inconspicuous.
Notes: Other species of Aristida are likely C4 based on information on Aristida spp. not included in this work (see: Ludwig et al.2010; Iverson et al. undated; Pascal-Antoine 2008; Waller an Lewis 1979).