Annual bluegrass Poa annua L.
Family: Poaceae
Life cycle: Annual and perennial biotypes
Habitat: Golf courses; poorly maintained turf
Native status: Introduced
General description: Short, clump-forming plant; plants flower from April to October.
Key ID traits: Leaves are folded in the bud; membranous ligule; tips of leaves have a ‘boat-prow’ appearance. Light green color. Plants flower nearly all season-long, even at very short mowing heights.
Similar species: Both Kentucky and rough bluegrass have boat tipped leaves, but generally are darker in color than annual bluegrass and these species spread by rhizomes (KY) and stolons (rough).
Miscellaneous: Annual bluegrass, often simply called Poa, is the most serious weeds of golf greens in the northern U.S. It has developed resistance to most herbicides available for use in turf, including glyphosate. Rather than trying to control it, many golf courses try to provide an environment favorable for its survival. However, annual bluegrass is poorly adapted to the heat of summer, so greens often decline in quality during mid-summer.
- Retired Weed Scientist and Professor of Agronomy
- Field Agronomist in Central Iowa