Smallflower umbrella sedge (Cyperus difformis)
Click on images to enlarge
Smallflower umbrella sedge, sometimes called smallflower umbrellaplant, a summer annual sedge, is an erect, grasslike plant. In California, it is found in the Central Valley and southwestern regions, to about 1600 feet (550 m). This sedge inhabits pond margins, ditches, and is particularly common in rice-growing areas. It typically grows in wet soil or shallow water, does not tolerate deep water, and grows best on fertile soil. This plant produces thousands of small seeds that become uniformly distributed over the ground. Some biotypes have developed tolerance to certain herbicides.
Cotyledons (seed leaves) are more or less football shaped, hairless, translucent, and very tiny, less than 1/25 of an inch (1 mm) long. The first leaf blade is bright green, with three veins, and roughly 1/6 to 1/3 of an inch (4–8 mm) long. At the three-leaf stage, narrow, grasslike leaves grow out in three directions at approximately 120° angles from one another. Seedling roots are sometimes pinkish.
Mature plants grow in clumps, reach about 12 to 16 inches (30–40 cm) tall, and produce round clusters of greenish brown to purplish spikelets at maturity. Several pithy stems, sharply triangular in cross-section and often with concave sides, rise from the base of the plant. Sheaths are closed. There are typically two to four basal leaves per stem that are slightly rough to the touch on the margins near the tips. Each stem has secondary leaves below the flower clusters. Roots are fibrous and sometimes reddish.
Flowering takes place from May through November. Flowers are greenish brown to purplish and cluster densely to form round, stalked or stalkless flower heads, each having two to three modified leaves below it.
The fruits are egg shaped, pale greenish brown, glossy, and very tiny—less than 1/25 of an inch (1 mm).
Reproduces by seed.
Related or similar plants
- Ricefield bulrush, Scirpus mucronatus
- Tall flatsedge, Cyperus eragrostis
- Tall umbrella sedge, Cyperus difformis