Cyperus rotundus , or Purple Nutsedge, is a perennial, glossy-green, grass-like Eurasian sedge or weed with an erect triangular stem branching into three stems of purple, antenna-like seedpods. Plants die back to the ground in fall, with new shoots emerging in spring from underground tubers. This species, as well as other sedges, grows best in wet sites, prefers warm weather and full sun conditions, but will grow in a diversity of sites and environments. Like its native cousin, Yellow Nutsedge ( Cyperus esculentus) , Purple Nutsedge spreads through slender elongated rhizomes and tubers found at the base of the stem and is destructive to crops in sunny, open fields and dry, disturbed soil. The rhizomes remove nutrients from the soil robbing their fellow plants and can be very difficult to remove. If you pull it up you can see the nut-like nodules that store the nutrients (and are edible) as well as a network of long roots. Unfortunately, once pulled up, the Nutsedge may leave broken roots to form more numerous roots and therefore, new plants in its place and seeds lay dormant for several years. It is best to remove young plants and leave exposed roots in the sun to dry out. It is considered one of the world’s worst weeds and is reported in more than 90 countries as a weed infesting at least 52 different crops. Diseases, Insects, and Other Plant Problems: No known insect or disease problems. This plant is allelopathic and removes nutrients from soil and its existence in a field significantly reduces crop yield. It is resistant to most herbicides and is one of the few weeds that cannot be stopped with plastic mulch.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day)
Soil texture
Clay; Loam (Silt); Sand
Soil pH
Acid (<6.0); Alkaline (>8.0); Neutral (6.0-8.0)
Soil drainage
Moist | Occasional Flooding | Occasionally Dry
Available space
Less than 12 inches
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 2 ft. 0 in. - 4 ft. 7 in. | Width: 0 ft. 2 in. - 0 ft. 5 in.
Growth rate
Rapid
Maintenance
High
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Ascending; Erect; Mounding; Spreading
Texture
Coarse
Foliage
Deciduous
Leaf color
Brown/Copper; Gold/Yellow; Green
Leaf type
Simple
Leaf arrangement
Alternate
Leaf feel
Glossy; Smooth
Leaf size
> 6 inches long, < 1 inch wide
Hairs present
No
Leaf detail
Three subtending leaves broad at base tapering to a point. Leaves up to 15 inches long and 1/3 of an inch wide. Scabrid on margin and major veins. Leaf sheath green to reddish-brown. Foliage dies back at first frost
Flower color
Brown/Copper
Flower form
Spike; Umbel
Flower size
< 1 inch
Flower detail
Large spikelets in short spikes occur at the ends of the solitary stems in a dense cluster where the flower stalks rise from a common point (umbel-like). Individual spikelets are reddish-purple to reddish-brown in color. Linear-lanceolate and slightly flattened, 1/4 to 3/4 of an inch long, 1/10 of an inch wide. Unequal rays support spikelets.
Bloom time
Spring; Summer
Fruit color
Brown/Copper; Gray/Silver
Fruit type
Achene
Fruit detail
Tiny, triangled smooth achenes.
Stem color
Green
Stem detail
Erect triangular stem on a mat-forming mound. Stems rise from tuber or basal bulb. Rounded, fiber-covered tubers at the stem bases.
Wildlife & Ecology
Native status
Non-native
Origin
Tropical and Subtropical Old World
Distribution
Southern and South Central United States
Food & Medicine
Edible parts
Tubers
Harvest time
Fall; Summer
Fruit type
Achene
Edibility
Tuber can be eaten but is described as more bitter and less useful than its near cousin, Cyperus esculentus.
Uses (ethnobotany)
Roots are staple carbohydrate in topical regions. Also used homeopathically.