Common Name: bluegrass, annual
Species: Poa annua L.
Bayer Code: POAAN

Annual bluegrass is a light green bunch-type to slightly spreading winter annual weedy grass. Some subspecies exist which are classified as short-lived perennials (Poa annua ssp. reptans). These perennial types are particularly evident in bentgrass golf greens. One reason annual bluegrass is so unsightly is its ability to produce a light colored seedhead even at very low mowing heights.
annual bluegrass
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annual bluegrass
annual bluegrass
annual bluegrass
annual bluegrass seedhead
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CharacteristicTypeDescription
Seedhead / Flower paniclelight-colored panicle seedhead
Vernation Type foldedleaves folded in the bud
Ligule Type membranoussharp pointed entire, 0.04 - 0.12 inches (1 - 3 mm) long
Growth Season / Life Cycle winter annual weed 
Auricle Type absent 
Leaf Blade Tip Shape boat shapedsmooth above and below, not glossy, light green; two distinct, clear lines, one on each side of the midrib
Leaf Blade Width narrow, less than 0.1 in0.08 - 0.1 inches (2 - 3 mm) wide
Stolon Presence absent 
Rhizome Presence absent 
Collar Type divideddistinct, not hairy, V-shaped
Sheath Margin openopen part way only
Sheath Type flattenedslightly sharply creased