Ditch Fimbry

Fimbristylis schoenoides is an unusual Fimbristylis for us, with a smooth, “eleocharis-like” appearance. The plants are mostly low and spreading-culmed, glabrous annuals of Asian origin.

Plants annual, cespitose, 10–35(–40) cm, glabrous; rhizomes absent. Leaves polystichous, mostly spreading to ascending; sheath margins entire; ligule present, complete; blades narrowly linear, to 1 mm wide, flat to shallowly involute, margins distantly scabrid, surface glabrous. Inflorescences: spikelets 1, terminal or 2–3 in simple anthela longer than broad, laterals subsessile; scapes narrowly linear, coarsely ribbed, distally compressed; involucral bracts usually 1 per spikelet, exceeding or exceeded by it. Spikelets yellowish, mostly turgidly ovoid, 5–8 mm; fertile scales broadly ovate, 2–3 mm, apex obtuse, entire, midrib excurrent or not. Flowers: stamens 3, styles 2-fid, flattened, fimbriate. Achenes near white to pale brown, lenticular-obovoid to obpyriform, 2 mm, appearing smooth under 10–20X magnification, under higher power finely longitudinally ribbed, with fine, isodiametric pits in vertical lines. 2n = 10.

Annual or perennial, 25-50 cm. Stem slender, terete or compressed, deeply grooved, grey-green. Leaves c. 1/2 of stem length; sheaths to 12 cm, brown, two uppermost longer than other, tight, mouth straight or oblique; ligule c. 0.2 mm, a fringe of hairs, not or slightly arched; blades c. 0.7 mm wide, resembling stem, canaliculate, margins involute, apex long, flat, scabrous. Inflorescence of 1-3 spikes; peduncles to 12 mm, with tubular prophyll; bracts glume-like, 3.4-6.5 mm, incl. arista of 1-4 mm. Spikes 5.4-6.2 x 3.8-4.2 mm, with 30-35 glumes, ovoid or ellipsoid, smoothly rounded, yellow-brown; spike rachis c. 0.8 mm diam., deeply notched, winged with pieces (remnants) from glume bases, reddish brown; glumes 2.5-3 mm, cymbiform, rounded, obtuse to acute, yellowish brown, with 4-6 paler nerves on both sides, glossy. Stamens 3, anthers 0.6-0.8 mm; style caducous, flat, ciliate above, stylopodium 0.3 x 0.2 mm; stigmas 2. Nut 1.6-1.9 x 1.1-1.2 mm, incl. stipe c. 0.2 mm, obovoid, bi- finely reticulate, pale yellow brown, glossy.

Nepal, India, Indo-China, southern China, Malaysia, N. Australia.

introduced; Ala., Fla., Ga., La., Miss.; tropical Asia; Africa.

Distribution: From Pakistan and India to S. China, Taiwan, Malaysia and N. Australia; introduced to S. USA.

200-900 m

Fruiting summer–fall, all year in south.

Moist sands or sandy peats of roadsides, ditches, flatwoods clearings, savanna, and particularly, disturbed low, open areas; 1–100m.

Scirpus schoenoides Retzius, Observ. Bot. 5: 14. 1789; Fimbristylis inconstans Steudel

Scirpus schoenoides Retz., Obs. Bot. 5: 14. 1789; Haines & Lye, Sedges and Rushes E. Afr.: figs. 150-151. 1983.