Crabgrass, a weed grass commonly found in lawns. Few weeds are more difficult to kill. Crabgrass sends out jointed stems along the ground; these take root and produce new plants. The long flowering stalk has fingerlike spikes. Crabgrass is killed by hand weeding or by treatment with a spray containing sulfate of iron. Certain herbicides will prevent the seeds from germinating if applied to the lawn in the early spring.
Crabgrass is Digitaria sanguinalis of the grass family, Gramineae.