Yellow nutsedge is a perennial weed in the sedge family and superficially resembles grass. Nutsedges are among the most noxious weeds of agriculture in temperate to tropical zones worldwide. They are difficult to control, often form dense colonies, and can greatly reduce crop yields. In California, nutsedges are particularly problematic in summer-irrigated annual and perennial crops, but yellow nutsedge is much more widespread than a related species, purple nutsedge, Cyperus rotundus. Yellow nutsedge grows throughout California to an altitude of roughly 3300 feet (1000 m). It resembles another sedge, green kyllinga, Kyllinga brevifolia. Yellow nutsedge is cultivated in some countries for its almond-flavored tubers, which are used to make a drink.
Seedling
Seedlings are infrequently found. When observed, seedling leaves are similar to that of the mature plant, but smaller with finer leaves. The stem base is slightly triangular and the midvein area is usually pale. The first two to three leaves emerge together, folded lengthwise.
Young Plant
Yellow nutsedge primarily propagates by tubers formed on underground, horizontal creeping stems called rhizomes, mostly in the upper foot of soil. Sprouts from tubers are similar in appearance to the mature plant.
Mature Plant
The yellow nutsedge stem is erect and hairless. Although its leaves superficially resemble grass leaves, they lack collars, ligules, and auricles. The leaves of yellow nutsedge are thicker and stiffer than most grasses, are V-shaped in cross-section, and arranged in sets of three from the base rather than sets of two as in grasses. Yellow nutsedge flowering stems are triangular in cross-section; grass stems are hollow and round. Yellow nutsedge can be distinguished from a related species, purple nutsedge by its longer stems, which grow up to 3 feet (0.9 m) tall; purple nutsedge grows only to 1-1/3 feet (0.4 m) tall. Yellow nutsedge has light green leaves, a pointed tip, and a leaf width of 1/6 to 2/5 of an inch (4–9 mm); in contrast purple nutsedge has dark green leaves that are 1/8 to 4/17 of an inch (3–6 mm) wide, with rounded tips. Yellow and purple nutsedge can also be distinguished by their tubers. Tubers of yellow nutsedge are produced singly, while purple nutsedge tubers are produced in chains, with several on a single, horizontal, underground stem (rhizome). Another sedge, green kyllinga, Kyllinga brevifolia, has no underground tubers.
Flowers
Yellow nutsedge spikelets are straw-colored to gold-brown with many flowers. Purple nutsedge spikelets are dark reddish to purplish brown with few flowers per cluster. Green kyllinga has green flowers on compressed flower heads.
Fruits
The tiny single-seeded fruits (achenes) are football shaped, triangular in cross-section, and brown in yellow nutsedge. Purple nutsedge does not typically produce seed in the United States.
Reproduction
Reproduces by tubers or "nutlets" that grow from horizontal, underground, creeping stems called rhizomes.
Related or Similar Plants
- Purple nutsedge, Cyperus rotundus
- Green kyllinga, Kyllinga brevifolia
- Smallflower umbrella sedge, Cyperus difformis
