E-Flora BC: Electronic Atlas of the Flora of British Columbia

Polygonum arenastrum Jord. ex Boreau
oval-leaved knotweed (oval-leaf knotweed)
Polygonaceae (Buckwheat family)

Introduction to Vascular Plants
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Distribution of Polygonum arenastrum
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Species Information

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Annual or occasionally perennial herb from a taproot; stems prostrate, ascending or sometimes erect, several, usually 3-angled, at least when young, usually branched, the main branches 10-80 cm tall/long.
Basal leaves narrowly lanceolate to oblong-lanceolate, pale or bluish-green, the blades 5-15 mm long, unstalked, jointed at the base; stem leaves alternate, stem and branch leaves usually similar, reduced upwards; sheathing stipules silvery, 4-6 mm long, ragged.
Inflorescence of 1-5 flowers in axillary clusters; perianths 2-3 mm long, green with pink or white margins, 5-lobed more than 1/2 the distance to the base.
Achenes, with one side concave and two sides convex, brown, dull, pimply in lines,1.6-2.2 mm long.
Often mistaken for P. aviculare, a species having stem and branch leaves dissimilar.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Mesic to dry disturbed sites, roadsides and waste places in the lowland, steppe and montane zones; infrequent in S BC, rare northward to 53degreeN; introduced from Eurasia.

Source: The Illustrated Flora of British Columbia


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Polygonum aequale Lindm.
Polygonum aviculare var. arenastrum (Jord. ex Boreau) Rouy
Polygonum montereyense Brenckle

Taxonomic and Nomenclatural Links

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