Weeds Identification Gallery

Blunt Spikerush

  • Eleocharis obtusa
  • Sedge Family: Cyperaceae
Updated: 01/2026

Blunt spikerush, a common annual sedge, may be found on poorly drained soil, levees, in shallow ditches and marshy areas. In California, it is mostly inhabits marshes and the edges of ponds and lakes in the northwestern region, Sierra Nevada, and Modoc Plateau to about 8500 feet (2600 m). Although seldom weedy in rice fields, it sometimes grows in irrigation canals associated with the crop. In natural areas it is a desirable component of the vegetation.

Seedling

Seedlings are grasslike with triangular stems.

Mature Plant

Mature blunt spikerush grows from 4 to 20 inches (10–50 cm) tall and has round, bladeless stems. It is characterized by a lack of underground, horizontal creeping stems (rhizomes) and its unique flower head and fruit.

Mature plant showing long, narrow, cylindrical stems with small egg-shaped flower heads; . Credit: Jack Kelly Clark, UC IPM
Mature plant. Credit: Jack Kelly Clark, UC IPM

Flowers

Stems do not have leaf blades. They terminate in a small, brown, densely egg-shaped or oblong flowering head with a rounded tip.

Flower head showing styles, 1/2X; . Credit: Jack Kelly Clark, UC IPM
Flowering plants. Credit: Jack Kelly Clark, UC IPM
Blunt spikerush (Eleocharis obtusa var. engelmanii) inflorescence. Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources
Flower head. Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources

Fruits

Fruits are somewhat egg shaped, roughly 1/25 to 1/17 of an inch (1–1.5 mm) long, pale brown and shiny.

Blunt spikerush (Eleocharis obtusa var. engelmanii) achenes. Credit: Jack Kelly Clark, UC IPM
Fruit. Credit: Jack Kelly Clark, UC IPM

Reproduction

Primarily by seed.

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