Weeds Identification Gallery

Smutgrass

  • Sporobolus indicus
  • Grass Family: Poaceae
Updated: 01/2026

Smutgrass is a tufted warm-season perennial grass that often invades irrigated pastures and turf areas particularly those with heavy grazing, foot traffic, or poor drainage. Sometime a black fungus called “smut” infects the flower clusters and upper leaves, hence the name smutgrass. This grass is found in the Sacramento Valley, northern San Joaquin Valley, San Francisco Bay region, Central Coast, South Coast, southern Peninsular Ranges, and elsewhere to about 3900 feet (1200 m). It is most problematic in southern part of the state.

Habitat

Smutgrass inhabits pastures (especially irrigated), ditches, turf, roadsides, crop fields, and other disturbed open places.

Smutgrass or wiregrass, several scattered plants growing in kikuyugrass golf course fairway. San Diego Co. by JKC.   Credit: Jack Kelly Clark, UC IPM
Infestation in turf. Credit: Jack Kelly Clark, UC IPM

Collar Region

Ligules are a fringe of minute hairs. There are no auricles.

Two grass stems with short -fringed ligules. Copyright information is at the bottom (Copyright 2007 The Regents of the University of California. All rights reserved.). Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources
Collar and sheath. Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources

Mature Plant

The mature plant grows in tufts up to 3-1/3 feet (1 m) long. Stems are round in cross-section, very tough and wiry, branched, fibrous at the base, and grow in a spreading to erect manner. Leaves are flat, rolled in the bud, have conspicuous veins, are hairless except for a few tiny hairs around the collar, and grow from 3-1/5 to 12 inches (8–30 cm) long and 1/8 to 1/5 inch (3–5 mm) wide. Sheaths are open and have intact or frayed, brown bases.

Densley tufted grass plant growing alone with longer flowering stems sticking uniformly up and out. Copyright information is at the bottom (Copyright 2007 The Regents of the University of California. All rights reserved.). Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources
Plant. Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources

Flowers

Flowers bloom mostly from July through October, but will bloom as early as April where mild winters occur. Single flowers form clusters called inflorescences in dense spikelike or racemelike branches (panicles) that range from 4 to 20 inches (10–50 cm), but can grow to 31 inches (80 cm). They are often gray-green or purplish.

Many flowering stems with tightly packed flowers from a plant. Copyright information is at the bottom (Copyright 2007 The Regents of the University of California. All rights reserved.). Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources
Flowering stems. Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources
Two flowering stems showing clusters of flowers. Copyright information is at the bottom (Copyright 2007 The Regents of the University of California. All rights reserved.). Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources
Flowering stems. Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources

Seeds

The brown seeds are approximately 1/25 inch (1 mm) long. They become sticky when moistened. Seeds disperse from the parent plant with water, mud, or clinging to animals, shoes, tires, tools, and agricultural equipment.

Ten florets, most with seeds inside or still attached. Seeds are oval and brown. A 1 mm bar shows the seeds are slightly more than 1 mm long and 0.5 to 0.75 mm wide. Copyright information is at the bottom (Copyright 2007 The Regents of the University of California. All rights reserved.). Credit: Jack Kelly Clark, UC IPM
Seeds and florets. Credit: Jack Kelly Clark, UC IPM

Reproduction

Smutgrass reproduces by seed and usually produces many seeds.

  • Poverty dropseed, Sporobolus vaginiflorus

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