Polygonum achoreum |
Polygonum douglasii |
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Blake's knotweed |
Douglas' knotweed, Douglas's knotweed |
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Habit | A highly variable, simple or freely-branched, erect annual 1-4 dm. tall. | |
Leaves | Alternate and numerous along the stem, linear to oblong, lanceolate or even ovate, 1-5 cm. long, sessile, jointed at the base, reduced to bracts above; stipules sheathing, 5-15 mm. long, lacerate. |
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Flowers | In loose, elongate racemes and in the leaf axils, 1-4 flowers per node, on pedicles 1-4 mm. long, soon reflexed; perianth 2.5-5 mm. long, the segments greenish with white, pink or reddish margins; stamens 8, occasionally fewer. |
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Fruits | Achene with three sharp angles, black, smooth and shining, about 3 mm. long. |
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Polygonum achoreum |
Polygonum douglasii |
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Flowering time | June-September | |
Habitat | Common in dry to moist areas, lowlands to middle elevations in the mountains. | |
Distribution | Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east to the Rocky Mountains and across the northern U.S. and Canada to the Atlantic Coast.
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Origin | Native | Native |
Conservation status | Not of concern | Not of concern |
Sibling taxa | ||
Web links |
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