Green kyllinga (Kyllinga brevifolia)
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Green kyllinga is a perennial sedge with narrow, grasslike leaves. In the warm season, green kyllinga grows more rapidly than most turfgrasses; its dense mats can even crowd out bermudagrass. Although it is most problematic in turf and ornamental plantings it also inhabits ditches and landscaped areas. In California it is found to about 1000 feet (300 m) in the Central Valley from Sacramento to Southern California, in the South and Central Coast regions from San Diego County probably to southeastern San Francisco Bay, but is not usually associated with agricultural land in the state. The plant grows best in moist or wet areas that receive full sun, but it can survive some shade and drying once established.
The mature plant can reach about 1-3/5 feet (50 cm) tall, but is usually much shorter and can tolerate even close mowing. It has one to three dark green, glossy, flat, hairless leaves that on average range from 2-2/5 to 6 inches (6–15 cm) long. Leaf edges and the lower midvein are sparsely covered with tiny barbs that are rough to the touch. Green kyllinga is dormant during the cool season, remaining green in mild-winter areas, and turning brown or purplish brown in colder regions. Although similar looking to yellow or purple nutsedge, green kyllinga does not have underground tubers and has green rather than yellow or purple flowers.
Flowers bloom from May through October and sometimes earlier in warm locations. Flowering stalks are triangular in cross-section and terminate in a globular, dense flower head consisting of green flowers. A group of three long leaflike structures (bracts) radiates out from the stalk beneath the flower head. There are thirty to seventy-five spikelets within each flower head, each one capable of producing one seed.
Seeds are flat, oval, roughly 1/8 of an inch (3 mm) long, half as wide, and germinate from spring through summer.
Reproduces by seed and from horizontal, creeping, underground stems (rhizomes) that can produce new shoots. Under appropriate conditions, new plants can form from rhizome fragments that have at least one stem joint (node).