Blunt spikerush (Eleocharis obtusa)
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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.
Seedlings are grasslike with triangular stems.
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.
Stems do not have leaf blades. They terminate in a small, brown, densely egg-shaped or oblong flowering head with a rounded tip.
Fruits are somewhat egg shaped, roughly 1/25 to 1/17 of an inch (1–1.5 mm) long, pale brown and shiny.
Primarily by seed.