Types of grasses that might be found in the yard on purpose include St. Augustine grass and Kentucky blue grass. Grasses that are considered weeds include broomsedge and barnyard grass.
St. Augustine grass is a type of sorghum. It grows in the warmer areas of the country and is noted for its tolerance for shade. Kentucky bluegrass is a cool-season grass that was brought over from Europe. It can grow well in all but the hottest areas of the country.
Broomsedge is a weed found at the margins of forests. It grows mostly in states east of the Mississippi River. Barnyard grass is a coarse, annual weed with a purplish tinge.