Common name for *Digitaria*, a creeping grass that can become a problem weed
Crabgrass (also written as 'crab grass') is the common name for Digitaria, a genus of about 300 species of grass.
The two main problem species are Digitaria sanguinalis and Digitaria ischaemum. Both of which have high growing branching stems but can adapt to grow close to the earth in mats.
Where allowed to flourish, crab grass will choke out the surrounding grass and leave depressions in the lawn.
Photo of Digitaria sanguinalis by Matt Lavin.