Cyperus odoratus


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Common name: Fragrant Flat Sedge, Rusty Flatsedge   
 

Water herb - shillong - ID plz Attachments (3). 4 posts by 3 authors.
A herb found growing in water, with grass-like leaves, in Shillong, in June.
Please help with identification.
Check for Cyperus odoratus. 
As said By ... this plant is indeed Cyperus odoratus L. commonly known as Fragnant Flatsedge. In U.S.A this amphibious plant is ubiquitous in distribution and hence has been tagged as an noxious weed though this plant is said to be native to Florida swamps.
Flat sedge is an emersed plant. Its overall appearance is typical of this large genus. Flat sedge grows abundantly along every kind of marshy shore and wet clearing. Parts of rusty flat sedge are eaten by ducks and other birds. There are over 50 species and varieties of Cyperus in Florida (Wunderlin, 2003). Flat sedge occurs in the eastern half of the U.S. and the along the Pacific coast; in PR and the Virgin Islands; and in eastern Canada (Kartesz, 1999).
Cyperus odoratus grows from 4 to 30 inches tall. It may have only a few leavesrising from the base, and a few loose sheaths. Leaves are about 1/2 inch wide and may be as long as the plant. The base of the inflorescence has 3 to 10 conspicuous leaf-like bracts. The bracts are about 1/2 inch wide and can be much longer than the inflorescence. The inflorescence may be from 1 to 18 inches long. It has several small bottlebrush-like clusters of spikelets.
Cyperus odoratus Linnaeus, Sp. Pl. 1: 46. 1753.
Rusty flatsedge
Cyperus acicularis (Nees) Steudel; C. californicus S. Watson; C. eggersii Boeckeler; C. engelmannii Steudel; C. ferax Richard; C. ferax subsp. engelmannii (Steudel) Kükenthal; C. ferax subsp. speciosus (Vahl) Kükenthal; C. ferruginescens Boeckeler; C. haenkei J. Presl & C. Presl; C. huarmensis (Kunth) M. C. Johnston; C. macrocephalus Liebmann; C. michauxianus Schultes; C. odoratus var. engelmannii (Steudel) J. Rich. Carter, S. D. Jones & Wipff; C. oxycarioides Britton; C. speciosus Vahl; C. squarrosus Linnaeus var. parvus Britton; Diclidium aciculare Schrader ex Nees; D. odoratum (Linnaeus) Schrader ex Nees; Mariscus ferax (Richard) C. B. Clarke; M. huarmensis Kunth; Torulinium eggersii (Boeckeler) C. B. Clarke; T. ferax (Richard) Urban; T. macrocephalum (Liebmann) T. Koyama; T. michauxianum (Schultes) C. B. Clarke; T. odoratum (Linnaeus) S. S. Hooper
Herbs, annual (or short-lived perennial). Culms trigonous, (4–)10–50(–130) cm × (0.5–)1–4 mm. Leaves flanged V- or inversely W-shaped, 5–30(–60) cm × 4–12 mm. Inflorescences: spikes 1–5(–12), loosely to densely cylindric, ovoid, or ±pyramidal, 10–20(–40) × (8–)10–30(–35) mm; rays (0–2)6–9(–12), 2–8(–13) cm; if rays absent, infloresence a single dense, capitate cluster of closely imbricate spikes; bracts (4–)5–8(–10), horizontal to ascending at 30–60°, (3–)10–25(–55) cm × 1–14 mm; rachilla hyaline or thickened bronze, carmine, or yellowish, wings clasping achene. Spikelets (10–)20–60(–100), linear-oblong to narrowly linear, cylindric to slightly flattened (when scale tips spreading), (5–)8–15(–38) × 0.8–1.3(–1.9) mm; floral scales (4–)8–12–(30), medially green, laterally reddish to stramineous to shiny brown or beige, medially 2–5-ribbed, laterally 1–3-ribbed, ovate to elliptic, (2–)2.2–2.8(–3.2) × (1.2–)1.4–1.6(–1.8) mm, apex entire or emarginate with mucro to 0.3 mm. Flowers: anthers (0.2–)0.3–0.4(–0.7) mm; styles 0.4–0.7(–1) mm; stigmas (1–)1.5–3 mm. Achenes brown, reddish brown, or black, stipitate, narrowly ellipsoid to oblong (rarely obovoid-oblong), (1–)1.2–1.5(–1.9) × 0.5–0.6(–0.75) mm, stipe 0.1–0.2 mm, apex acute to barely obtuse, surfaces finely papillose.
Fruiting summer–early fall. Emergent shorelines, disturbed, muddy places, fresh or slightly brackish marshes; 0–1500 m; Ont., Que.; Ala., Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., Wash., W.Va., Wis.; Central America; South America; Asia; Africa; Pacific Islands (Hawaii); Australia.
As circumscribed here, Cyperus odoratus is easily identified by its cylindric to subcylindric spikelets in which the corky rachilla of the mature spikelet disarticulates at the base of each scale. The mature spikelet breaks into segments each consisting of a scale and an internode of the rachilla clasping the achene with its corky wings. Cyperus odoratus is an exceedingly variable pantropical and warm-temperate species. Numerous segregates have been named, some of which may deserve recognition when the species is studied in detail worldwide.
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