Herbs, annual, cespitose. Culms to 30 cm, bases soft. Leaves spreading to ascending, ΒΌ-1/3 length of scapes; sheath borders tan, backs prominently ribbed, glabrous; blades filiform, 0.5 mm wide, involute, margins ciliate-scabrid, surface glabrous. Inflorescences solitary or more commonly in simple, open, rarely compact, involucrate anthelae; scapes filiform (rarely with several spikelets sessile or subsessile at plant base), prominently ribbed, glabrous; proximalmost involucral bract cuspidate or setaceous bladed, exceeding or exceeded by inflorescence. Spikelets red-brown, ovoid to lanceoloid, 3-5 mm; fertile scales ovate, 1.5-2 mm, apex acute, glabrous or distally puberulent, keel prominent, short-excurrent. Flowers: stamens (1-)2; anthers oblong-elliptic, 0.5-0.7 mm. Achenes yellowish to pale brown, trigonous-obovoid, 1 mm, faces rugose. 2n = 84. Fruiting summer-fall. Sandy savanna, prairie, arenaceous outcrops, sandy or gravelly waste areas; 0-3000 m; N.B., N.S., Ont., Que.; Ala., Ariz., Ark., Calif., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis.; Mexico; West Indies; Central America; South America; Asia; Pacific Islands. A specimen of Bulbostylis capillaris collected by E. Hall (#585) gives Oregon without a specific locality. Bulbostylis capillaris is distributed over a broad range of physiographic types and occurs in many forms, the most distinctive of ours being var. crebra, which has, in addition to numerous long scaped anthelae, large numbers of spikelets at the plant base.
Tufted annual to 3 dm; scapes capillary; lvs short, slender, to 0.5 mm wide, involute, smooth or with scabrous margins; spikelets lance-ovoid or ovate, acute, 3-5 mm, few-fld, 2-7 in open, umbelliform cymes; scales ovate, curved-keeled, with a prominent, often shortly excurrent midrib; anthers 2, 0.5 mm; achene obovoid-trigonous, 1 mm, stramineous, finely cross-rugulose; tubercle minute, depressed-globose. Dry, open, often rocky or sandy places; Me. to Minn., s. to Fla., Tex., Ariz., C. Amer., and W.I.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.