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Asian flatsedge

Habit Plants annual, cespitose.
Culms

1–15, trigonous, 7–30 cm × 1.2–2.5 mm; soft (flattened in pressing).

Leaves

(2)7–22 cm × 2.2–4 mm.

Inflorescences

clusters head-like; dense, 7–17(35) mm wide;

rays (0)1–5, 2–32 mm; longest inflorescence bract erect or nearly so, appearing as continuation of culm; other bracts horizontal to ascending.

Spikes

30–120, oblong-ellipsoid, compressed; (2)3–5(6) × 0.8–1.2 mm; greenish brown to purplish brown; floral scales (6)12–20(30), obovate to orbiculate, 0.6–0.8 × 0.6–0.8 mm, stramineous to deep purple with clear margins; mid-stripe greenish, stramineous, or purplish;

lateral ribs 0; medial ribs 3;

apex mucronulate.

Flowers

anthers 0.1 mm;

styles 0.1 mm;

stigmas 0.1–0.3 mm.

Achenes

obovoid-ellipsoid, 0.6–0.8 × 0.3–0.4 mm (as long as subtending scale);

base cuneate.

Cyperus difformis

Distribution
[WildflowerSearch map]
[BONAP county map]
Discussion

Disturbed, sandy or muddy soils, sand bars, roadsides, sometimes on serpentine. 100–400 m. Sisk. CA, ID; east to NJ, south to Mexico; South America; Africa, Australia, Eurasia, islands of the Pacific and Indian Oceans; Exotic.

Cyperus difformis is recognized by its tight heads of small spikes with unusually small scales. The first Oregon collection was made in 2004.

Source Flora of Oregon, volume 1, page 235
Barbara Wilson, Richard Brainerd, Nick Otting
Sibling taxa
C. acuminatus, C. aggregatus, C. bipartitus, C. eragrostis, C. erythrorhizos, C. esculentus, C. fuscus, C. niger, C. odoratus, C. schweinitzii, C. squarrosus, C. strigosus
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