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fork fimbry

Habit Plants perennial, cespitose, (10–) 20–80 cm, base thickened, not bulbous; rhizomes absent. Plants annual, cespitose, delicate, to 30(–40) cm, bases soft; rhizomes absent.
Leaves

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, spreading to ascending, to 1/2 length of culms or longer;

sheaths entire or ciliate distally, backs hirtellous;

ligule absent;

blades linear-filiform, 0.5 mm wide, flat or involute, scabridciliate, often abaxially hirtellous.

Inflorescences

anthelae compound, dense or open, ascending-branched, longer than broad;

scapes slender, 1 mm wide, slightly compressed distally;

proximalmost involucral bract exceeding anthela.

anthelae simple or compound, mostly open, ascending-branched, mostly longer than broad;

scapes filiform, 0.5 mm wide, distally compressed, mostly glabrous;

longer involucral bracts leafy, equaling or exceeded by anthela.

Spikelets

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 brownish, lanceoloid or narrowly ellipsoid-cylindric, 4–5 mm;

fertile scales ovate, acute, glabrous, midrib excurrent as slender, excurved cusp.

Flowers

stamens 1–2;

styles 2-fid, flat, fimbriate.

stamens 1;

styles 2-fid, slender, base flat, long-fimbriate, hairs recurved over achene summit.

Achenes

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, lenticular, obovoid, 0.9 mm, smooth or very finely reticulate.

2n

= 20, 30.

Fimbristylis dichotoma

Fimbristylis squarrosa

Phenology Fruiting summer–fall, into winter southward.
Habitat Moist, usually sandy waste areas, roadsides, low fields, and savannas Moist sands or silts, low clearings, fields
Elevation 0–200 m (to 2000 m, tropics) (0–700 ft (to 6600 ft, tropics)) low to high elevations
Distribution
from FNA
AL; FL; GA; LA; MS; NC; SC; TX; Mexico; Central America; South America; Atlantic Islands; Pacific Islands; Indian Ocean Islands; West Indies; Africa; Eurasia; Bermuda; Australia [Introduced in North America]
[WildflowerSearch map]
[BONAP county map]
from FNA
NJ; South America; West Indies (Cuba); Central America (Honduras); Asia; Africa; Indian Ocean Islands; Pacific Islands [Introduced in North America]
[BONAP county map]
Discussion

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 squarrosa is an Old World temperate to tropical weed, mostly of Asia and Africa.

While Fimbristylis squarrosa has been collected only once in North America from ballast at Camden, New Jersey (C. F. Parker, in 1865), the weedy and often ruderal nature of the species makes it a likely future adventive.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 23, p. 125. FNA vol. 23, p. 127.
Parent taxa Cyperaceae > Fimbristylis Cyperaceae > Fimbristylis
Sibling taxa
F. annua, F. autumnalis, F. brevivaginata, F. caroliniana, F. castanea, F. cymosa, F. decipiens, F. miliacea, F. perpusilla, F. puberula, F. schoenoides, F. squarrosa, F. thermalis, F. tomentosa, F. vahlii
F. annua, F. autumnalis, F. brevivaginata, F. caroliniana, F. castanea, F. cymosa, F. decipiens, F. dichotoma, F. miliacea, F. perpusilla, F. puberula, F. schoenoides, F. thermalis, F. tomentosa, F. vahlii
Synonyms Scirpus dichotomus, F. annua var. diphylla, F. brizoides, F. diphylla subsp. diffusa, F. glauca, F. polymorpha, Scirpus diphyllus F. comata, F. hirta, Isolepis hirta, Pocronostylis squarrosus
Name authority (Linnaeus) Vahl: Enum. Pl. 2: 287. (1805) Vahl: Enum. Pl. 2: 289. (1805)
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