Flora of North America species comparison

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Ageratina paupercula

Ageratina adenophora

Santa Rita snakeroot

Crofton weed, eupatory, Mexican devil, sticky snakeroot, thoroughwort
Habit Perennials or subshrubs, to 100 cm. Subshrubs, 50–220 cm.
Stems

erect, puberulent to glabrate.

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

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.

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

2–6 mm, puberulent.

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

2.5–3 mm.

3.5–4 mm.
Corollas

white, lobes sparsely hispid-villous.

white, pink-tinged, lobes sparsely hispidulous.
Phyllaries

apices acute, abaxial faces puberulent-hispidulous.

apices acute, abaxial faces stipitate-glandular.
Heads

clustered.

clustered.
Cypselae

glabrous.

glabrous.
2n

= 51.

Ageratina paupercula

Ageratina adenophora
Phenology Flowering Mar–May. Flowering Mar–Aug(–Sep).
Habitat Rocky slopes, crevices, gravelly, sandy streambeds, pine-oak woodlands Stream margins, ditches, road embankments, hillsides
Elevation 1000–1800 m (3300–5900 ft) 400–900 m (1300–3000 ft)
Distribution
from FNA
AZ; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; Mexico; Intoduced [Also introduced in Europe, Pacific Islands (New Zealand)]
[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. 551. 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. rothrockii, A. shastensis, A. thyrsiflora, A. wrightii
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 pauperculum Eupatorium adenophorum
Name authority (A. Gray) R. M. King & H. Robinson: Phytologia 19: 215. (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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