Annual bluegrass, also known as poa annua, is a short, cool-season grass that is characterized by its leaf tip, which is shaped like the bow of a boat. Grass leaves branch off from a single stem, creating a cluster and bushy appearance. Annual bluegrass is not actually blue. Instead it varies between a yellowish green to dark green color. Bluegrass produces flowers which are usually visible December through July. This type of grass is identifiable by the look of its flowers. The flowers are 1 to 3 inches long, open and have pyramidal shaped leafs.
Annual bluegrass is the most common and widely distributed grassy weed in the world. It grows in dense, low clumps and grows fast in damp, shady areas. When the weather gets hot, this type of grass dies off leaving big, brown empty patches in your lawn.
Annual bluegrass can be very difficult to control because it can adapt to a variety of environments. Hand pulling or hoeing to remove this grass can be effective as long as it is done frequently, which can be a tedious process.