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How to Manage Pests

Identification: Weed Photo Gallery

Smooth crabgrass

Scientific name: Digitaria ischaemum (Grass Family: Poaceae)

Click on image to enlarge

Life stages of Smooth crabgrass mature plant seedling flower clusters flowers and flower parts clusters collar and sheath

A common weed in turf, smooth crabgrass is a low-growing, summer annual grass that spreads by seed and from occasional rooting of the lowest joints of the stems. In California it is found in the Central Valley, San Francisco Bay region, northern Sierra Nevada, Central Coast, and South Coast, up to an elevation of 2600 feet (about 800 m). In California, smooth crabgrass is more often found in turf whereas large crabgrass is more often found in gardens or landscape areas. It can provide good forage for livestock.


Crop fields, orchards, vineyards, gardens, landscaped areas, turf, nurseries, pastures, roadsides, ditches, and other disturbed places.

Mature plant

Stems grow mostly upright, sometimes prostrate, and are usually branched at the base. Stems are flattened in cross-section. Leaves are flat, rolled in the bud, have a prominent midvein, and are 1/4 to 1/3 of an inch (6–8 mm) wide, up to 5 inches (12.5 cm) long, and pointed. The leaves are hairless except for some long hairs at the position of auricle, and sometimes, sparse hairs on the lower leaf surface. Some leaf bases have a reddish tint. Smooth crabgrass is distinguished from large crabgrass, D. sanguinalis, by its shorter, wider leaf and lack of hairs. It is most often found in turfgrass.

Collar region

Ligules are short and membranous. There are no auricles.


Flowering takes place from September through November. Flowers cluster along spikelike branches in one, or more often, two whorls at the stem tip.


Spikelets are under 1/10 of an inch (about 2.5 mm), football shaped, and have a stalk with a disklike tip.


Reproduces by seed.

Related species/Similar looking plants

Large crabgrass

More information

Statewide IPM Program, Agriculture and Natural Resources, University of California
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