Polygonum aviculare |
Polygonum austiniae |
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Austin's knotweed |
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Habit | 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. | |
Leaves | 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. |
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Flowers | 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. |
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Fruits | Achene with 3 sharp angles, brownish, smooth. |
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Polygonum aviculare |
Polygonum austiniae |
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Identification notes | Achene 3-angled, black, smooth, shining, 2.5 mm. long, ovate in outline but tapered at both ends. | |
Flowering time | May-October | June-August |
Habitat | Dry or slightly moist, disturbed soil, often where hard-packed. | Dry to moist banks and flats, from sagebrush plains to lower mountains, often with ponderosa pine. |
Distribution | Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.
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Occurring east of the Cascades crest in Washington; British Columbia to California, east to Alberta and Wyoming.
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Origin | Both native and introduced | Native |
Conservation status | Not of concern | Threatened in Washington (WANHP) |
Sibling taxa | ||
Subordinate taxa | ||
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