16. Fimbristylis miliacea (Linnaeus) Vahl, Enum. Pl. 2: 287. 1805 (as miliaceum).
Scirpus miliaceus Linnaeus, Syst. Nat. ed. 10, 868. 1759; Fimbristylis littoralis Gaudichaud; Isolepis miliacea (Linnaeus) J. Presl & C. Presl; Scirpus bengalensis Persoon; Trichelostylis miliacea (Linnaeus) Nees
Plants annual, cespitose, 15–50(–70) cm, glabrous, base soft; rhizomes absent. Leaves distichous, in fans, to ca. 2/3 plant height; sheaths keeled, equitant, margins entire; ligule absent; blades bifacial (flattened in same plane as sheath), narrowly triangular linear, to 2 mm wide, margins scabrid at least distally. Inflorescences: anthela compound, usually diffuse, branched, broadening upward, often as broad as long; scapes slender, angularly ribbed and/or somewhat compressed distally, 1–1.5 mm wide or thick; involucral bracts exceeded by anthela. Spikelets dark red-brown, broadly ovoid to near round, 2–4 min; fertile scales broadly ovate to orbiculate, 1 mm, glabrous, apex broadly rounded, midrib not excurrent. Flowers: stamens 1–2; styles 3-fid, slender, base dilated, apex pubescent. Achenes pale brown, tumid, obovoid, 1 mm, apiculate, reticulate, with pits narrowly rectangular in 4–6 vertical rows per side, the longitudinal ribs most prominent and mostly warty. 2n = 10.
Fruiting summer–fall, all year southward. Moist to wet sands and alluvia of open river and stream bottoms, low fields, drawdowns, shores, flatwoods, savanna, seeps, and open disturbed waste places; 0–200 m; introduced; Ala., Ark., Fla., Ga., Ky., La., Miss., Mo., N.C., S.C., Tenn., Tex.; Mexico; Central America; South America; Asia; Africa; Indian Ocean Islands; Pacific Ocean Islands; Australia.
Fimbristylis miliacea is another widespread annual weed whose origin is probably in the Asian rice belt. Two Linnaean types bear the epithet “miliacea.” A good argument exists that Vahl, first to adopt the plant as a Fimbristylis, took the round-spikeleted element as F. miliacea; the other, ovoid, acute-spikeleted element thus became F. quinquangularis (Vahl) Kunth.
Because Gaudichaud’s epithet “littoralis” was not applied to the complex until 1826, it is invalidated in any case.