University of Missouri Extension

IPM1024, Revised October 2010

Identifying Grass Seedlings

Annual bluegrass (Poa annua)

Winter annual grasses

Description

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. Mature annual bluegrass.
 

Collar region Prowlike tip of bladeCollar region: prominent, membranous ligule.
Right, prowlike tip of blade.
 

Habitat

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.

Distribution

Annual bluegrass is scattered nearly throughout the United States. In Missouri, it is less common north of the Missouri River.

Similar species

There are approximately 10 Poa species present in Missouri; all share some common physical features but vary in their life cycles.

 

IPM1024 Identifying Grass Seedlings | University of Missouri Extension

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