is a species of grass
known by the common name hairy crabgrass
. It is one of the more well-known species of crabgrass
, and one that is known nearly worldwide as a common weed. It is an annual grass with an inflorescence
of up to nine very long, very thin, radiating branches atop its stems. Each branch is lined with pairs of very tiny spikelets
. The inflorescences may be reddish or purplish.