Flora of North America species comparison

The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Ageratina adenophora

Ageratina rothrockii

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

Rothrock's snakeroot
Habit Subshrubs, 50–220 cm. Perennials, (20–)40–70(–150) cm (slender, fibrous-rooted crowns, with slender rhizomes).
Stems

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

ascending to erect, puberulent to glabrate.
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 2–20 mm;

blades (3–5-nerved) lanceolate to lanceolate-ovate, mostly 3–6 × (1.5–)2–3 cm, bases obtuse to truncate, margins serrate to crenate, apices acute to acuminate, sparsely puberulent abaxially, mostly along nerves.
Peduncles

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

5–12(–20) mm, puberulent.
Involucres

3.5–4 mm.

5–7 mm.
Corollas

white, pink-tinged, lobes sparsely hispidulous.

white, lobes short-villous.
Phyllaries

apices acute, abaxial faces stipitate-glandular.

apices acute, abaxial faces glabrous or glabrescent, eglandular.
Heads

clustered.

clustered.
Cypselae

glabrous.

sparsely and finely strigose-hirsute.
Powell

on label].
2n

= 51.

= 85 [ca. 100, fide A. M.

Ageratina adenophora

Ageratina rothrockii
Phenology Flowering Mar–Aug(–Sep). Flowering (Jul–)Aug–Oct.
Habitat Stream margins, ditches, road embankments, hillsides Rocky slopes and ledges, in oak-juniper, pine-oak, pine, aspen, and spruce-fir woodland
Elevation 400–900 m (1300–3000 ft) 1700–2400 m (5600–7900 ft)
Distribution
from FNA
CA; Mexico; Intoduced [Also introduced in Europe, Pacific Islands (New Zealand)]
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, Sonora)
[WildflowerSearch map]
[BONAP county map]
Discussion

Ageratina rothrockii is similar to A. altissima, probably its western vicariant, and the two perhaps would be justifiably treated as conspecific.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 21, p. 553. FNA vol. 21, p. 550.
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. herbacea, A. jucunda, A. lemmonii, A. luciae-brauniae, A. occidentalis, A. paupercula, A. shastensis, A. thyrsiflora, A. wrightii
Synonyms Eupatorium adenophorum Eupatorium rothrockii
Name authority (Sprengel) R. M. King & H. Robinson: Phytologia 19: 211. (1970) (A. Gray) R. M. King & H. Robinson: Phytologia 19: 216. (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).



Type/paste one or more Latin names into the boxes above; matching taxa will show up below the box as you type. You can use the up/down arrow keys to move through the list.

(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Fabaceae, Apiaceae, Boraginaceae, and Polemoniaceae.)

Choose a data source: Flora of North America

The species comparison tool is brought to you by:
Northwest Wildflowers