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Weed Identification

smooth crabgrass



Scientific Name

Digitaria ischaemum

Other Common Names:

small crabgrass

Synonyms (former Scientific Names):

Digitaria ischaemum var. mississippiensis
Syntherisma ischaemum
Panicum ischaemum


Although smooth crabgrass typically acts as an annual, it may persist as a perennial. Typically, smooth crabgrass germinates in spring, grows during the summer, sets seed in the fall, and dies in the winter. Smooth crabgrass can withstand close mowing heights and is highly competitive with desirable turfgrass


Leaves have smooth edges and typically lack hairs. Veins are inconspicuous and the leaf surface is smooth and light green.

Identifying Characteristics

Smooth crabgrass usually lacks hairs unlike large crabgrass or southern crabgrass which are completely hairy and marginally hairy, respectively. Smooth crabgrass has a large membranous ligule like other crabgrass plants. Older smooth crabgrass plants are red at the base of the plant. The collar area is usually smooth but may have a few short hairs.

Flower Seed Head

Seedheads have three to five spikelets with multiple seeds in an open arrangement. Spikelets are borne on a slender smooth stalk and are usually about 8 inches tall but may be much shorter if the area is mowed regularly.

Seed Fruit

Seed are light brown and about 1/16 to 1/8 inch long and about 1/16 inch wide. Seed are pointed at both ends and flat to oval in thickness. Seed may have short hairs.

Where Found

Most types of turfgrass. May tolerate close mowing typical of putting greens or close-cut fairways. Smooth crabgrass and large crabgrass make up most of the crabgrass populations in Virginia lawns and turfgrass areas.

Leaf Hair on Upper Surface

no hairs
hairs on basal half only

Leaf Arrangement

rolled in bud

Mature Leaf Width

less than 5 mm
6 to 15 mm


flat or oval


multiple spikes

Root Structure


Life Cycle

summer annual


not present



Ligule Length

less than 1 mm
1-2 mm
2-3 mm

Plant Type