Ageratina altissima

(Linnaeus) R. M. King & H. Robinson

Phytologia 19: 212. 1970.

Common names: White snakeroot
IllustratedEndemic
Basionyms: Ageratum altissimum Linnaeus Sp. Pl. 2: 839. 1753,
Treatment appears in FNA Volume 21. Treatment on page 549. Mentioned on page 548, 550, 551.

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 ovatelanceolate, 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

"fine" is not a number.

... more about "Ageratina altissima"
villous +, sparsely +  and glabrous +
not tailed +, truncate +, rounded +  and obtuse +
scarious +
usually ovate +  and lanceolate +
usually terete +  and clavate +
indeterminate +  and determinate +
Guy L. Nesom +
(Linnaeus) R. M. King & H. Robinson +
cordate +, usually rounded +  and truncate or obtuse +
enlarged +
Ageratum altissimum +
3(-5)-nerved +
11 cm110 mm <br />0.11 m <br /> (13 cm130 mm <br />0.13 m <br />) +
8 cm80 mm <br />0.08 m <br /> (9 cm90 mm <br />0.09 m <br />) +
4 cm40 mm <br />0.04 m <br /> (11 cm110 mm <br />0.11 m <br />) +
dissected +, lobed +, toothed +  and entire +
ovatelanceolate;usually deltate-ovate;ovate or broadly lanceolate +
2.5cm;8cm +
papillate +  and rugose +
(4-)5-angled;10-ribbed +
White snakeroot +
scabrellous +
fusiform +  and prismatic +
fertile +  and bisexual +
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. +
puberulent +, pilose +, hispidulous +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
indeterminate +
each +  and sessile +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
campanulate +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
short-villous +
lanceolate +  and lance-linear +
2-carpellate +
persistent +
0.1 cm1 mm <br />0.001 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
3 cm30 mm <br />0.03 m <br /> (5 cm50 mm <br />0.05 m <br />) +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
2-nerved +  and 0-nerved +
8 +  and 30 +
subequal +  and unequal +
bearing subulate enations +, hairy +  and bristly +
exalbuminous +
Illustrated +  and Endemic +
semiscandent +, ascending +  and erect +
appendaged +  and truncate +
hirsutulous +
papillate +
Compositae +
Ageratina altissima +
Ageratina +
species +
obconic +  and campanulate +
80 cm800 mm <br />0.8 m <br /> (120 cm1,200 mm <br />1.2 m <br />) +
50 cm500 mm <br />0.5 m <br /> (80 cm800 mm <br />0.8 m <br />) +
shrub +  and subshrub +