Flora of North America species comparison

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Ageratina wrightii

Ageratina adenophora

Wright's snakeroot

Crofton weed, eupatory, Mexican devil, sticky snakeroot, thoroughwort
Habit Shrubs, 50–150 cm. Subshrubs, 50–220 cm.
Stems

erect, puberulous.

(usually purplish when young) erect, stipitate-glandular.
Leaves

opposite proximally, alternate on distal 1/3–1/2 of stem;

petioles narrowly winged, 3–5(–8) mm;

blades ovate to deltate-ovate, mostly 1–2 × 0.5–1.5(–2) cm, bases truncate to cuneate or attenuate, margins entire or shallowly crenate, apices acute to blunt or obtuse, abaxial faces gland-dotted.

opposite;

petioles 10–25 mm;

blades (abaxially purple) ovate-lanceolate or ovate-deltate to lanceolate-ovate, (1.5–)2.5–5.5(–8) × 1.5–4(–6) cm, bases cuneate to obtuse or nearly truncate, margins serrate, apices acute to acuminate, abaxial faces stipitate- to sessile-glandular.
Peduncles

1–3 mm, puberulent.

5–12 mm, densely stipitate-glandular and sometimes also sparsely viscid-puberulent.
Involucres

3.5–4.5 mm.

3.5–4 mm.
Corollas

pinkish white to pink, glabrous.

white, pink-tinged, lobes sparsely hispidulous.
Phyllaries

apices acute, abaxial faces puberulent.

apices acute, abaxial faces stipitate-glandular.
Heads

clustered.

clustered.
Cypselae

sparsely hispidulous.

glabrous.
2n

= 51.

Ageratina wrightii

Ageratina adenophora
Phenology Flowering (Jul–)Aug–Oct(–Nov). Flowering Mar–Aug(–Sep).
Habitat Limestone slopes, ledges, alluvium, in brushy vegetation Stream margins, ditches, road embankments, hillsides
Elevation 1300–2200 m (4300–7200 ft) 400–900 m (1300–3000 ft)
Distribution
from FNA
AZ; NM; TX; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; Mexico; Intoduced [Also introduced in Europe, Pacific Islands (New Zealand)]
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 21, p. 552. FNA vol. 21, p. 553.
Parent taxa Asteraceae > tribe Eupatorieae > Ageratina Asteraceae > tribe Eupatorieae > Ageratina
Sibling taxa
A. adenophora, A. altissima, A. aromatica, A. havanensis, A. herbacea, A. jucunda, A. lemmonii, A. luciae-brauniae, A. occidentalis, A. paupercula, A. rothrockii, A. shastensis, A. thyrsiflora
A. altissima, A. aromatica, A. havanensis, A. herbacea, A. jucunda, A. lemmonii, A. luciae-brauniae, A. occidentalis, A. paupercula, A. rothrockii, A. shastensis, A. thyrsiflora, A. wrightii
Synonyms Eupatorium wrightii Eupatorium adenophorum
Name authority (A. Gray) R. M. King & H. Robinson: Phytologia 19: 228. (1970) (Sprengel) R. M. King & H. Robinson: Phytologia 19: 211. (1970)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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