Flora of North America species comparison

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Ageratina adenophora

Ageratina paupercula

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

Santa Rita snakeroot
Habit Subshrubs, 50–220 cm. Perennials or subshrubs, to 100 cm.
Stems

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

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 3–15 mm;

blades narrowly to broadly lanceolate, (2–)3–7 × 0.5–1.5 cm, margins coarsely and remotely serrate, apices long-acuminate, abaxial faces sparsely pubescent.
Peduncles

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

2–6 mm, puberulent.
Involucres

3.5–4 mm.

2.5–3 mm.
Corollas

white, pink-tinged, lobes sparsely hispidulous.

white, lobes sparsely hispid-villous.
Phyllaries

apices acute, abaxial faces stipitate-glandular.

apices acute, abaxial faces puberulent-hispidulous.
Heads

clustered.

clustered.
Cypselae

glabrous.

glabrous.
2n

= 51.

Ageratina adenophora

Ageratina paupercula
Phenology Flowering Mar–Aug(–Sep). Flowering Mar–May.
Habitat Stream margins, ditches, road embankments, hillsides Rocky slopes, crevices, gravelly, sandy streambeds, pine-oak woodlands
Elevation 400–900 m (1300–3000 ft) 1000–1800 m (3300–5900 ft)
Distribution
from FNA
CA; Mexico; Intoduced [Also introduced in Europe, Pacific Islands (New Zealand)]
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Ageratina paupercula is recognized by its early spring flowering, relatively small and usually narrowly lanceolate and acuminate leaves, relatively small heads in clusters, and relatively small (1.2–1.4 mm versus mostly 2–3 mm in other species), glabrous cypselae.

(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. herbacea, A. jucunda, A. lemmonii, A. luciae-brauniae, A. occidentalis, A. rothrockii, A. shastensis, A. thyrsiflora, A. wrightii
Synonyms Eupatorium adenophorum Eupatorium pauperculum
Name authority (Sprengel) R. M. King & H. Robinson: Phytologia 19: 211. (1970) (A. Gray) R. M. King & H. Robinson: Phytologia 19: 215. (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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