Fimbristylis perpusilla

Plants annual, delicate, cespitose, slender, 2-15 cm; rhizomes absent. Leaves polystichous, spreading to ascending, mostly excurved, exceeding or exceeded by culms; sheaths entire, backs glabrous; ligule absent; blades setaceous-filiform, to 0.5 mm wide, flat to involute, sparsely scabrid-ciliate. Inflorescences: anthelae mostly simple, open, nearly as broad as long, ascending-branching, umbelliform, of 3-10 cormose spikelets; scapes filiform, 0.5-0.6 mm thick; proximalmost involucral bracts setaceous-bladed, exceeding anthela. Spikelets pale green to light brown, ovoid to globose or short-cylindric, 2-5 mm; fertile scales lance-linear to oblong-linear, 1.5 mm, glabrous, midrib strongly excurrent, erect to excurved cusp. Flowers: stamens 1; styles 2-fid, slender, glabrous. Achenes pale brown with iridescent tints, curved-cylindric, 0.4-0.6 mm, finely reticulate, in 12 vertical rows of narrowly rectangular, horizontal cells. 2n = 10.

Fruiting summer-fall. Fluctuating sandy-silty shores of shallow ponds, pine savanna pools, reservoirs, ditches, and canals; of conservation concern; 0-100(-200) m; Del., Ga., Md., N.C., S.C., Tenn., Va.

The nearest relative of this ephemeral is Fimbristylis dipsacea, a similarly diminutive Eurasian and South American annual with broader, more spreading cusped spikelets and oddly compound-papillate fruit.

Much like no. 8 [Fimbristylis vahlii (Lam.) Link], glabrous, even smaller, to 8 cm, with solitary or clustered stems; spikelets 2-4 mm, ovoid or subglobose, in a more open, umbelliform infl; style equaling or only slightly longer than the pale, terete, slightly curved, banana-shaped, finely reticulate achene; 2n=10. Alluvium of borders of pineland ponds; rare and irregular from Ga. to Md

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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