Tall flat sedge, tall nutgrass, umbrella sedge
Most low-elevation regions of California; small areas of Oregon and Washington
Roadsides, moist grassland, ditches; sea level to 600 feet
Up to 20 inches long and around a third of an inch wide
Cyperus eragrostis, is one of 129 US species in this genus, part of the pycnostachys subgroup which is characterized by florets with three (rather than two) stigmas, three-angled seeds, and spikelets (the inflorescence) arranged in hand-shaped clusters rather than elongated clusters. The green stems are triangular in cross-section, hairless, several feet tall, and produce a whorl of long, strap-like leaves at the tip, bending back downwards. Leaves have prominent lengthwise veins.
The inflorescence forms in spring at the base of the upper leaves; it consists of 3 to 10 rays, bearing between 30 and 50 spikelets, each of which carries between 20 and 30 florets. The inflorescence is colored greenish yellow, often brown towards the center of the spikelets.