Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.
Habitat: Dry or slightly moist, disturbed soil, often where hard-packed.
Flowers: May-October
Origin: Both native and introduced
Growth Duration: Annual
Conservation Status: Not of concern
Pollination: Bees, flies
Highly variable species, prostrate and spreading (but not rooting at the nodes) to occasionally erect, freely-branched annual, the stems terete, striate, up to 1 m. long.
Numerous, bluish-green, only slightly reduced upward, narrowly oblong, 1-3 cm. long and 2-6 mm. broad, narrowed to a very short, jointed petiole; stipules lacerate, 3-6 mm. long.
1-3 in the axils of the leaves or leaf-like bracts, the pedicles 1-3 mm. long, erect; perianth 2.5 mm. long, divided 2/3 the length, the segments 5, oblong, sub-equal, greenish with white to pink or red margins.
Achene with 3 sharp angles, brownish, smooth.
Publication: Sp. Pl. 1: 362. 1753.
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ssp. aviculare – common knotweed, yard knotweed
Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast. -
ssp. buxiforme – American knotweed, prairie knotweed Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.
- ssp. depressum – common knotweed, oval-leaf knotweed Occurring chiefly west of the Cascades crest in Washington; Alaska to California, east to the Atlantic Coast.
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ssp. neglectum – narrow-leaf knotweed Occurring chiefly west of the Cascades crest in Washington; Alaska to California, east to the Atlantic Coast.
PNW Herbaria: Specimen records of Polygonum aviculare in the Consortium of Pacific Northwest Herbaria database.
WA Flora Checklist: Polygonum aviculare checklist entry.
OregonFlora: Polygonum aviculare information.
E-Flora BC: Polygonum aviculare atlas page.
CalPhotos: Polygonum aviculare photos.
USDA Plants: Polygonum aviculare information.
