Fimbristylis dichotoma
Fimbristylis cymosa
fork fimbry
hurricanegrass
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.
polystichous, mostly spreading-excurved, to 1/2 as long as culms;
sheaths usually entire;
ligule absent;
blades linear, 2–3 mm wide, flat or shallowly involute, margin scabrid, apex blunt.
anthelae compound, dense or open, ascending-branched, longer than broad;
scapes slender, 1 mm wide, slightly compressed distally;
proximalmost involucral bract exceeding anthela.
simple or compound anthelae with numerous small pedunculate clusters of sessile spikelets;
scapes linear, distally terete, 1–2 mm thick;
involucral bracts short, usually shorter than inflorescence.
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.
greenish brown or yellow-brown, ovoid, 2–3 mm;
fertile scales broadly ovate, 1–1.5 mm, obtuse or apically notched, midrib not excurrent.
stamens 1–2;
styles 2-fid, flat, fimbriate.
stamens usually 1;
styles 2-fid, slender, glabrous.
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.
dark brown to nearly black, tumidly obovoid, rarely obscurely 3-ribbed, 1 mm, faintly striate to variously warty, faintly reticulate.
= 20, 30.
= 56.
Fimbristylis dichotoma
Fimbristylis cymosa
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.)
New World examples of Fimbristylis cymosa are almost exclusively bicarpellate, with bifid styles; Old World Oceania examples are tricarpellate, with trifid styles, a form not covered in this treatment.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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