Polygonum aviculare
Family: Polygonaceae
common knotweed, doorweed, prostrate knotweed
Polygonum aviculare image
Robert R. Kowal  
Etymology: Polygonum: derived from the Greek words polys, "many," and gonu, "knee or joint," hence "many joints" because of the thickened joints on the stem
Plants: sprawling, annual, 1'-6' long forb; stems with many branches, nodes thin and translucent, becoming jagged
Leaves: alternate, flat, jointed at the base; early leaves lance-like and 3 times as large as the later ones
Flowers: white to pink-edged, 5-parted, 1/16"-1/8" long, petals and petal-like sepals with flat tips, joined at the base, the outer 3 not longer than the other 2 ; inflorescence small clusters from the leaf axils; blooms Aug.-Oct.
Fruits: dark brown, dull, dry seed
Habitat: disturbed sites
Conservation Status: Introduced - naturalized