Annual bluegrass: Short, slender grass which will form mats. Leaves are 1-4 mm wide, no auricles, and short ligules 1-3 mm long and hairless. The leaf tips are boat shaped. The seeds are borne on long branches forming an open pyramid shaped panicle. The seed head is 3-10 cm tall. Blooms all summer. Annual bluegrass spreads vigorously by seed.