Ageratina altissima

(Linnaeus) R. M. King & H. Robinson
Phytologia 19: 212. 1970.
Common names: White snakeroot
IllustratedEndemic
Basionym: Ageratum altissimum Linnaeus Sp. Pl. 2: 839. 1753,
Treatment appears in FNA Volume 21. Treatment on page 549. Mentioned on page 548, 550, 551.
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Perennials, (30–)50–80(–120) cm (bases usually fibrous-rooted crowns, sometimes rhizomatous). Stems ascending to erect, sometimes semiscandent, puberulent (hairs minute, crisped). 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. Heads clustered. Peduncles 1–5 mm, puberulent. Involucres 4–5 mm. Phyllaries: apices acute, abaxial faces glabrous or sparsely and finely villous. Corollas white, lobes sparsely short-villous. Cypselae glabrous.

Distribution

V21-1390-distribution-map.gif

N.B., N.S., Ont., Que., Sask., Ala., Ark., Conn., Del., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Mass., Md., Mich., Minn., Miss., Mo., N.C., N.Dak., N.H., N.J., N.Y., Nebr., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Va., Vt., W.Va., Wis.

Discussion

Varieties 2 (2 in the flora).

Selected References

None.

Key

1 Phyllaries 3–5 mm, apices not cuspidate Ageratina altissima var. altissima
1 Phyllaries 4–7 mm, apices cuspidate to acuminate Ageratina altissima var. roanensis
... more about "Ageratina altissima"
Guy L. Nesom +
(Linnaeus) R. M. King & H. Robinson +
Ageratum altissimum +
White snakeroot +
N.B. +, N.S. +, Ont. +, Que. +, Sask. +, Ala. +, Ark. +, Conn. +, Del. +, Fla. +, Ga. +, Ill. +, Ind. +, Iowa +, Kans. +, Ky. +, La. +, Maine +, Mass. +, Md. +, Mich. +, Minn. +, Miss. +, Mo. +, N.C. +, N.Dak. +, N.H. +, N.J. +, N.Y. +, Nebr. +, Ohio +, Okla. +, Pa. +, R.I. +, S.C. +, S.Dak. +, Tenn. +, Tex. +, Va. +, Vt. +, W.Va. +  and Wis. +
Illustrated +  and Endemic +
Compositae +
Ageratina altissima +
Ageratina +
species +