Flora of North America species comparison

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Ageratina adenophora

Ageratina herbacea

Crofton weed, eupatory, Mexican devil, sticky snakeroot, thoroughwort

desert ageratina, fragrant snakeroot, white thoroughwort
Habit Subshrubs, 50–220 cm. Perennials or subshrubs, (20–)30–60(–80) cm (woody crowns and woody rhizomes).
Stems

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

erect (brittle), minutely puberulent.
Leaves

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.

opposite;

petioles 10–25 mm;

blades triangular to lanceolate-ovate or ovate, 2–5(–7) × 1.5–3.5(–4.5) cm, bases truncate to shallowly cordate, margins dentate to serrate-dentate, abaxial faces sparsely hispidulous to glabrate, eglandular.
Peduncles

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

4–15 mm, puberulent.
Involucres

3.5–4 mm.

4–5 mm.
Corollas

white, pink-tinged, lobes sparsely hispidulous.

white, glabrous.
Phyllaries

apices acute, abaxial faces stipitate-glandular.

apices acute, abaxial faces granular-puberulent.
Heads

clustered.

clustered.
Cypselae

glabrous.

finely strigose-hispidulous.
2n

= 51.

= 34.

Ageratina adenophora

Ageratina herbacea
Phenology Flowering Mar–Aug(–Sep). Flowering (Jul–)Aug–Oct.
Habitat Stream margins, ditches, road embankments, hillsides Pine, pine-oak, juniper, and pinyon-juniper woodlands, rocks along streams, slopes, ridges, washes
Elevation 400–900 m (1300–3000 ft) 1400–2700(–2900) m (4600–8900(–9500) ft)
Distribution
from FNA
CA; Mexico; Intoduced [Also introduced in Europe, Pacific Islands (New Zealand)]
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Chihuahua, Coahuila, Sonora)
[WildflowerSearch map]
[BONAP county map]
Discussion

Ageratina herbacea is recognized by the distinctive color of its usually yellow-green, sometimes grayish, leaves, granular-puberulent involucres (with minute, thickened, eglandular hairs), and woody rhizomes.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 21, p. 553. FNA vol. 21, p. 551.
Parent taxa Asteraceae > tribe Eupatorieae > Ageratina Asteraceae > tribe Eupatorieae > Ageratina
Sibling taxa
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
A. adenophora, A. altissima, A. aromatica, A. havanensis, A. jucunda, A. lemmonii, A. luciae-brauniae, A. occidentalis, A. paupercula, A. rothrockii, A. shastensis, A. thyrsiflora, A. wrightii
Synonyms Eupatorium adenophorum Eupatorium ageratifolium var. herbaceum, Eupatorium herbaceum
Name authority (Sprengel) R. M. King & H. Robinson: Phytologia 19: 211. (1970) (A. Gray) R. M. King & H. Robinson: Phytologia 19: 222. (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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