Forest & Kim Starr, Wikimedia.org
Crowfootgrass gets its name from the seed heads, which resemble the foot of a crow. Each weed is capable of producing as many as 60,000 seeds, so it's important to get rid of the weeds quickly to prevent a nasty infestation in the yard. This summer annual grows in bunches and is found in sandy soil, preferring thin, unhealthy turf. It has long leaf blades with stiff hairs at the base.
Creating a dense, healthy turf is one way to prevent crowfootgrass from taking hold and spreading in the yard. It's a very invasive plant and can spawn thousands of other weeds due to its massive seed production. A pre-emergent herbicide application throughout the lawn can also help to curb and prevent weed growth.