Cyperaceae: Cyperus odoratus
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Family Name
Cyperaceae
Common Name
Fragrant flatsedge
Description
Cyperus odoratus is an annual or short-lived perennial sedge with a fibrous root system and sometimes tuberous rhizomes, allowing moderate vegetative spread. The erect stems (culms) are slender, triangular in cross-section, and range from 10 to 80 cm tall. Leaves are grass-like, alternate, linear, and smooth to rough, typically 5–30 cm long and 2–5 mm wide, with rough margins and sheathing bases that wrap closely around the stem base. The ligule is short and inconspicuous, often appearing as a small fringe of hairs or a thin membrane. Flowering occurs from summer through fall (June–October). Inflorescences are compound umbels with multiple rays, each bearing clusters of small spikelets. Spikelets are lanceolate to ovate, 2–5 mm long and consist of many brown to purplish-brown flowers covered by overlapping scales. Flowers have three stamens and a pistil with three stigmas. The fruit is a small, lens-shaped achene, about 1–2 mm long, brown at maturity, ripening from late summer into fall. Fragrant flatsedge is native to South Dakota, occurring in wetlands, marshes, ditches, riverbanks, and moist disturbed soils statewide, with higher concentrations in eastern and central regions.
Horticulture Notes
Seed Collection: Seeds mature when spikelets turn brown and dry; mature achenes can be collected in late summer to early fall.
Germination: Seeds germinate readily without dormancy; sow in moist soil in spring or summer.
Vegetative Propagation: Not typically propagated vegetatively; spreads mostly by seed.
Soils: Prefers wet, poorly drained to saturated soils; tolerates standing water and fluctuating water levels.
Light: Grows best in full sun to partial shade.
Water: Requires wet to saturated soils; tolerates periodic flooding.
Additional Notes
Fragrant flatsedge is important to wetland ecosystems, stabilizing soil, offering erosion control along waterways and wetlands, and providing habitat and food for waterfowl, amphibians, and aquatic invertebrates. Traditionally it has been used in some cultures for basketry and weaving.