Ageratina altissima var. altissima |
Ageratina altissima |
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common white snakeroot, eupatoire rugueuse, white snakeroot |
white snakeroot |
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Habit | Perennials, (30–)50–80(–120) cm (bases usually fibrous-rooted crowns, sometimes rhizomatous). | |||||
Stems | ascending to erect, sometimes semiscandent, puberulent (hairs minute, crisped). |
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Leaves | opposite; petioles (5–)10–30(–50) mm; blades usually deltate-ovate to ovate or broadly lanceolate, sometimes ovate-lanceolate, 4–11(–13) × 2.5–8(–9) cm, bases usually rounded to truncate or obtuse, sometimes cordate, margins coarsely and doubly incised-serrate, apices usually acuminate. |
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Peduncles | 1–5 mm, puberulent. |
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Involucres | 4–5 mm. |
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Corollas | white, lobes sparsely short-villous. |
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Phyllaries | 3–5 mm, apices not cuspidate. |
apices acute, abaxial faces glabrous or sparsely and finely villous. |
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Heads | clustered. |
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Cypselae | glabrous. |
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Ageratina altissima var. altissima |
Ageratina altissima |
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Phenology | Flowering Jul–Oct(–Nov). | |||||
Habitat | Moist forests, cove forests | |||||
Elevation | 10–800 m (0–2600 ft) | |||||
Distribution |
AL; AR; CT; DE; FL; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; ND; NE; NH; NJ; NY; OH; OK; PA; RI; SC; SD; TN; TX; VT; WI; WV; NB; NS; ON; QC; SK |
AL; AR; CT; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; ND; NE; NH; NJ; NY; OH; OK; PA; RI; SC; SD; TN; TX; VA; VT; WI; WV; NB; NS; ON; QC; SK
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Discussion | Plants with narrow leaves, generally in the southwest part of the range of Ageratina altissima, have been recognized as var. angustata and were so mapped by A. F. Clewell and J. W. Wooten (1971), who indicated that all var. angustata occurs west of the Mississippi River and that this taxon was completely congruent in distribution with var. altissima. The present treatment confirms the westward tendency toward size reduction and observes that narrow-leaved plants occur widely through the southeast United States (including Arkansas, Kentucky, Louisiana, North Carolina, Oklahoma, Tennessee, and Texas). The transition is gradual and the region of intergradation is wide. In Texas, where the leaves mostly are narrow, plants with broad, cordate leaves are scattered through the range. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 21, p. 549. | FNA vol. 21, p. 549. | ||||
Parent taxa | ||||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | A. altissima var. angustata, Eupatorium rugosum, Eupatorium rugosum var. chlorolepis, Eupatorium rugosum var. tomentellum, Eupatorium urticifolium | Ageratum altissimum | ||||
Name authority | unknown | (Linnaeus) R. M. King & H. Robinson: Phytologia 19: 212. (1970) | ||||
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