Smallflower Umbrella Sedge

Nile region, oases and Mediterranean region.

Portugal, Mediterranean Europe, Cyprus, Egypt, tropical Africa, Palestine, Syria, Turkey, Caucasus, Iraq, Arabia, Iran,Afghanistan, India, central Asia, Korea, China, Japan, Philippines, Sumatra, Java, Hawaii, Australia, introduced to north and central America.

Rice fields, canal banks, ditches, marshes.

Annual.

Cyperus difformis is naturalized in the New World and native to the Old World, where it ranges from southern Europe to southern Africa and eastward to Southeast Asia and Australia.

Herbs, annual, cespitose. Culms 1–15, trigonous, 7–30 cm × 1.2–2.5 mm, soft (flattened in pressing), glabrous. Leaves 2–7, flat, (2–)7–22 cm × 2.2–4 mm. Inflorescences: heads dense, 7–17 mm diam.; when rays short, heads sessile or nearly so, then densely irregularly lobate, 12–35 mm diam.; rays 1–5, 2–32 mm; bracts 2–4, longest bract erect or nearly so, appearing as continuation of culm, other bracts horizontal to ascending, 1–22 cm × 0.5–3.5 mm, margins and keel minutely scabridulous. Spikelets 30–120, greenish brown to purplish brown, oblong-ellipsoid, compressed, (2–)3–5(–6) × 0.8–1.2 mm; floral scales (6–)12–20(–30), laterally clear margins, stramineous to deep purple, medially greenish, stramineous, or purplish, laterally ribless, medially 3-ribbed, obovate to orbiculate, 0.6–0.8 × 0.6–0.8 mm, apex mucronulate. Flowers: stamens 1 or 2; anthers ovoid-ellipsoid, 0.1 mm, connective not prolonged; styles 0.1 mm; stigmas 0.1–0.3 mm. Achenes light brown, obovoid-ellipsoid, 0.6–0.8 × 0.3–0.4 mm (as long as subtending scale), base cuneate, apex obtuse, apiculate, surfaces finely reticulate, papillose.

Annual, 25-60 cm. Roots reddish-brown. Stem c. 3 mm diam., sharply trigonous, smooth. Leaves shorter than stem; sheaths to c. 10 cm, green or yellow-brown, sometimes with reddish tint, mouth oblique; ligule c. 1 mm, papery, arch of attachment higher than wide; blades up to 50 cm, 3-5 mm wide, keeled, margins smooth, apex trigonous, scabrous. Inflorescence of 1-7 globose partial inflorescences, nearly sessile or peduncles to 30 mm; partial inflorescences 7-15 mm diam., axis tightly digitately branching and rebranching, with c. 100 or more sessile spikes. Bracts 2-3, lowest two foliose, to 20 cm or more, sheath-less. Spikes 2-5 x c. 1 mm, with 5-20 flowers; glumes c. 0.7 mm, deeply cymbiform, blunt, wider than long, midnerve strong, sides brown or dark brown, margins narrowly scarious; rachis compressed, slightly zigzagging, internodes c. 0.8 mm. Stamens 2. Nut c. 0.5 mm, obovoid, sharply trigonous, papillose, yellowish.

Tropical, subtropical and temperate regions of both hemispheres. Common in rice fields.

Distribution: Common weed from 35o S to 45o N in tropical and subtropical areas of all continents; from S. Europe to Turkey, Iraq, Caucasus, Uzbekistan, Tadjikistan, Pakistan and India.

introduced; Ala., Ariz., Calif., Fla., Ga., Idaho, Ky., La., Miss., N.J., N.Mex., N.C., Oreg., Pa., S.C., Tenn., Tex., Va.; Mexico; West Indies (Puerto Rico); Central America (Nicaragua, Panama); South America; Eurasia; Indian Ocean Islands; Pacific Islands; Australia.

100-2700 m

Fl. Per.: July – October.

Fruiting summer.

Disturbed, muddy soils, shallow waters; 0–1000m.

Rice fields, ditches, irrigation channels, grassy swamps.

Cyperus lateriflorus Torrey

Cyperus difformis is a species of sedge known by several common names, including variable flatsedge, smallflower umbrella-sedge and rice sedge. This plant is native to southern Europe, most of Africa and Asia, and Australia, and it is naturalized in other areas of the world, including large parts of the Americas.

Cyperus difformis is a plant of aquatic and moist habitats. It is a weed of rice fields, but not generally a troublesome one. This is an annual herb with one to many thin, soft erect stems reaching over 30 centimeters in maximum height. There are usually a few long, wispy leaves around the base of the plant. The inflorescence is a rounded bundle one to three centimeters wide, containing up to 120 spikelets, each long and partially or entirely covered in up to 30 bracted flowers. The flowers are light brown with areas darker brown and sometimes a yellowish or purplish tint.