Identifying Grass Seedlings
Annual bluegrass (Poa annua)
Winter annual grasses
Annual bluegrass is a clump-forming grass that sometimes roots at its lower nodes and forms mats. Although it can tolerate close mowing, annual bluegrass can reach 2 feet in height if left unmowed. Sheaths are flat and smooth. Leaf blades are flat, smooth and 2–3 mm wide with a prowlike tip. Auricles are absent, and the ligule is a prominent, rounded to acute membrane.
Mature annual bluegrass.
Collar region: prominent, membranous ligule.
Right, prowlike tip of blade.
Annual bluegrass poses a problem in high-maintenance turfgrass settings. Its seed is a common contaminant of Kentucky bluegrass lawn seed. The white seedheads form quickly at close-mowing heights and disrupt the uniformity of golf course greens. It grows best in rich, moist soils but will tolerate compacted sites.
Annual bluegrass is scattered nearly throughout the United States. In Missouri, it is less common north of the Missouri River.
There are approximately 10 Poa species present in Missouri; all share some common physical features but vary in their life cycles.