Polygonum paronychia Cham. & Schltdl.
black knotweed (beach knotweed)
Polygonaceae (Buckwheat family)

Introduction to Vascular Plants

Photograph

© Jim Riley     (Photo ID #884)


Map

E-Flora BC Static Map

Distribution of Polygonum paronychia
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Species Information

General:
Perennial semi-shrub from a strong, fibrous root; stems prostrate to ascending, several, freely branched, smooth, rooting at the branch nodes, 30-100 cm tall/long.
Leaves:
Basal leaves lacking; stem leaves alternate, narrowly oblong but rolled under and so appearing linear in outline, the blades 1-2 cm long, unstalked; stipules translucent, ragged.
Flowers:
Inflorescence of several flowers in clusters in the upper leaf axils; perianths white to pink, 5-6 mm long, unequally 5-lobed 1/2 to 3/4 the distance to the base.
Fruits:
Achenes, 3-angled, 4-5 mm long, black, smooth, shiny.

SourceThe Illustrated Flora of British Columbia

Illustration

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Habitat and Range

Moist to mesic sand dunes and beaches in the lowland zone; infrequent on S Vancouver Island and the Gulf Islands; S to CA.

SourceThe Illustrated Flora of British Columbia