Flora of North America species comparison

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Ageratina occidentalis

Ageratina wrightii

western boneset, western eupatorium, western snakeroot

Wright's snakeroot
Habit Perennials or subshrubs, 15–70 cm (caudices woody, rhizomatous). Shrubs, 50–150 cm.
Stems

(green or purple) erect or ascending, puberulent.

erect, puberulous.
Leaves

opposite proximally, alternate on distal 1/4–1/2 of stems;

petioles 5–12 mm;

blades triangular to ovate, 2.5–5 × 1.7–4 cm, bases truncate to cuneate, margins serrate, apices acute, abaxial faces gland-dotted.

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.
Peduncles

2–5 mm, minutely puberulent.

1–3 mm, puberulent.
Involucres

3–3.5(–4) mm.

3.5–4.5 mm.
Corollas

pink, bluish, or white tinged with purple, lobes glabrous or glabrate.

pinkish white to pink, glabrous.
Phyllaries

apices acute, abaxial faces viscid-puberulent and/or sessile-glandular.

apices acute, abaxial faces puberulent.
Heads

clustered.

clustered.
Cypselae

sessile-glandular.

sparsely hispidulous.
2n

= 34.

Ageratina occidentalis

Ageratina wrightii
Phenology Flowering (Jun–)Jul–Sep. Flowering (Jul–)Aug–Oct(–Nov).
Habitat Crevices, outcrops, rocky slopes, ridges, talus, gravelly and sandy stream bars, mixed hardwood-conifer woodlands, aspen, open and brushy vegetation Limestone slopes, ledges, alluvium, in brushy vegetation
Elevation (40–50)900–2800(–3200) m ((100–200)3000–9200(–10500) ft) 1300–2200 m (4300–7200 ft)
Distribution
from FNA
CA; ID; MT; NV; OR; UT; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; TX; Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Ageratina occidentalis is the only species of the genus in the flora area with sessile-glandular cypselae; peduncles also may be sessile-glandular. Its identity also can be confirmed among flora area species by its relatively long (5–6 mm) corollas.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 21, p. 552. FNA vol. 21, p. 552.
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. 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. rothrockii, A. shastensis, A. thyrsiflora
Synonyms Eupatorium occidentale Eupatorium wrightii
Name authority (Hooker) R. M. King & H. Robinson: Phytologia 19: 224. (1970) (A. Gray) R. M. King & H. Robinson: Phytologia 19: 228. (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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