Fimbristylis interior Britton in N. L. Britton and A. Brown, Ill. Fl. N. U.S. ed. 2, 1: 320, fig. 785. 1913

Plants with culm bases tufted; rhizomes orangish, scaly, slender, often contorted, not covered with old leaf bases. Leaves: backs of leaf sheaths and of involucral bracts glabrous; ligule present, usually complete; blades with margins glabrous or very distantly scabridulous, surfaces glabrous. Fertile scales glabrous.

Fruiting summer–fall. Moist sands, sandy clays or sandy silts of prairie swales, grassy alluvial terraces along streams; 0–1000 m; Ariz., Kans., Nebr., N.Mex., Okla., Tex., Utah.

Fimbristylis puberula var. interior is like the more slender forms of F. caroliniana in general habit, differing only in the less flattened, more slender scape, the involute leaf blades, and in its less hairy or glabrous spikelet. The Arizona distribution is based on a specimen collected in 1847 by A. Fendler (A. Fendler, 876, GH), who did not provide a precise locality.