Ambrosia chamissonis |
Ambrosia trifida |
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beach bur-sage |
giant ragweed |
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Habit | Plants perennial, 5–40 dm, mat-forming; taprooted or from root crowns. | |
Stems | prostrate or decumbent; simple to much branched; ± densely pilose to villous or strigose. |
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Leaves | alternate; blades lanceolate, broadly elliptic, obovate, or triangular; surfaces strigose-canescent, petiolate. |
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Involucres | cup-shaped. |
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Pistillate florets | 1. |
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Staminate florets | 8–30+. |
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Phyllaries | of staminate heads connate, sometimes with black midribs; tips shallowly lobed; surfaces glabrous or strigose; of pistillate heads erect, separate, marginally glabrous or pilose. |
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Burs | ovoid, 5–10 mm, variously pubescent; spines flattened, spreading or arched outward, 0.5–2 mm. |
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2n | =36. |
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Ambrosia chamissonis |
Ambrosia trifida |
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Distribution | ||
Discussion | Western North America. 2 varieties. |
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Source | Flora of Oregon, volume 2, page 172 Kenton Chambers |
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Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Franseria chamissonis | Ambrosia trifida var. trifida |
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