Fimbristylis dichotoma
Fimbristylis miliacea
fork fimbry
nearly distichous, spreading to ascending, 1/2 length of culms;
sheaths distally ciliate, backs mostly glabrous;
ligule line of short hairs;
blades narrowly linear, 2–3 mm wide, flat to broadly involute, scabridciliate, adaxially smooth or hirtellous.
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 triangularlinear, to 2 mm wide, margins scabrid at least distally.
anthelae compound, dense or open, ascending-branched, longer than broad;
scapes slender, 1 mm wide, slightly compressed distally;
proximalmost involucral bract exceeding anthela.
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.
pale drab brown to chestnut brown, ovoid-lanceoloid, 4–8 mm;
fertile scales broadly oblong or ovate, 2 mm, acute to obtuse angled, glabrous, midrib reaching scale tip or excurrent, finely mucronate.
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.
stamens 1–2;
styles 2-fid, flat, fimbriate.
stamens 1–2;
styles 3-fid, slender, base dilated, apex pubescent.
white to brownish, lenticular, obovoid, 1–1.2 mm, cancellate, each face longitudinally with (5–)10–12 ribs, connected by vertical rows of horizontally rectangular pits.
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.
= 20, 30.
= 10.
Fimbristylis dichotoma
Fimbristylis miliacea
Fimbristylis dichotoma is found in temperate to tropical regions worldwide. It is one of the most widespread and weedy species of Fimbristylis, unquestionably with many races and forms. The two commonest forms in the United States often occur in mixed populations, one sort with inflorescence branches more ascending, inflorescence dense, habit lower, and leaves broader; the other sort usually taller, inflorescence more sparse, branches more widely spreading, and leaves more ascending and narrower. The abundance of such plants both in regions where rice originated and in regions where rice is, or was, introduced, indicates an Asian origin for such weeds.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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