Fimbristylis squarrosa Vahl

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.

Plants annual, cespitose, delicate, to 30(–40) cm, bases soft; rhizomes absent. Leaves 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, scabrid ciliate, often abaxially hirtellous. Inflorescences: 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 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; styles 2-fid, slender, base flat, long-fimbriate, hairs recurved over achene summit. Achenes pale brown, lenticular, obovoid, 0.9 mm, smooth or very finely reticulate.

Annual, forming small tufts, up to 15 cm. Stem 0.1-0.2 mm diam., triangular or compressed, glabrous. Leaves c. equalling stem; sheaths to 2.5 cm, wide, green, one side prominently nerved, other side scarious, villous, mouth oblique; blades 0.2-0.4 mm wide, slightly involute, abaxial side pubescent, adaxial side glabrous. Inflorescence to 3 cm diam., of 4-20 spikes; the lowest bracts frequently twice as long as inflorescence, 0.1-0.3 mm wide, sparingly pubescent; branches triangular or compressed, smooth. Spikes mostly solitary, pedunculate, 3-6 mm, with 8 to 30 glumes, more or less angular, greenish to greenish brown; rachis castaneous, with narrow hyaline wings; glumes 2-3 mm, lanceolate to ovate, sparingly villous, with prominent, green mid-rib, arista to 1.5 mm, margins widely scarious. Stamens 1; filaments 1-1.5 mm; anthers narrowly oblong, connective tip prominent; style c. 0.5 mm, upper part slightly ciliate, stylopodium fringed with long, retrorse hairs; stigmas 2, c. 0.5 mm long, ciliate. Nut 0.6-0.7 x 0.5 mm, lenticular, smooth, yellowish brown.

Tropical, subtropical and temperate regions of both hemispheres.

Distribution: Tropical and temperate regions; S. Europe, Asia, Africa and S. America.

500-1500 m

Fl. Per.: October.

Rice fields and similar moist places; 4000-7000 ft.

Moist sands or silts, low clearings, fields; low to high elevations; introduced; N.J.; West Indies (Cuba); Central America (Honduras); South America; Asia; Africa; Indian Ocean Islands; Pacific Islands.

Fimbristylis comata Nees; F. hirta (Kunth) Roemer & Schultes; Isolepis hirta Kunth; Pocronostylis squarrosus (Vahl) Bertoloni

F. aestivalis (Retz.) Vahl var. squarrosa (Vahl) T. Koyama in J. Fac. Sc. Univ. Tokyo. Sect. 3, 8: 116. 1961; F. squarrosa Vahl subsp. squarrosa, Koyama in Fl. Taiwan 5: 246. 1979; Scirpus squarrosus Poir. in Lam., Encycl. Meth. Bot. Suppl. 5: 100. 1806 non L.; F. comata Nees, in Wight, Contrib. Bot. Ind.: 102. 1834; Clarke, Ill. Cyper.: Tab. 41. 1909. Haines & Lye, Sedges and rushes E. Afr.: figs. 152-153. 1983.