Family: Polygonaceae
common knotweed, doorweed, prostrate knotweed
Robert R. Kowal
Emmet J. Judziewicz
University of Wisconsin - Madison (WIS-VP)
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
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
Flora of North America: Flora of North America Floristic Rating: Wetland Indicator = FAC- USDA Plants Database: Federal Distribution and detailed information including photos
Emmet J. Judziewicz
Janice Stiefel
Janice Stiefel
Emmet J. Judziewicz
from USDA Plants website
Botanical Illustration
Botanical Illustration
