Flora of North America species comparison

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Ageratina wrightii

Ageratina herbacea

Wright's snakeroot

desert ageratina, fragrant snakeroot, white thoroughwort
Habit Shrubs, 50–150 cm. Perennials or subshrubs, (20–)30–60(–80) cm (woody crowns and woody rhizomes).
Stems

erect, puberulous.

erect (brittle), minutely puberulent.
Leaves

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.

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

1–3 mm, puberulent.

4–15 mm, puberulent.
Involucres

3.5–4.5 mm.

4–5 mm.
Corollas

pinkish white to pink, glabrous.

white, glabrous.
Phyllaries

apices acute, abaxial faces puberulent.

apices acute, abaxial faces granular-puberulent.
Heads

clustered.

clustered.
Cypselae

sparsely hispidulous.

finely strigose-hispidulous.
2n

= 34.

Ageratina wrightii

Ageratina herbacea
Phenology Flowering (Jul–)Aug–Oct(–Nov). Flowering (Jul–)Aug–Oct.
Habitat Limestone slopes, ledges, alluvium, in brushy vegetation Pine, pine-oak, juniper, and pinyon-juniper woodlands, rocks along streams, slopes, ridges, washes
Elevation 1300–2200 m (4300–7200 ft) 1400–2700(–2900) m (4600–8900(–9500) ft)
Distribution
from FNA
AZ; NM; TX; Mexico
[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. 552. FNA vol. 21, p. 551.
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. paupercula, A. rothrockii, A. shastensis, A. thyrsiflora
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 wrightii Eupatorium ageratifolium var. herbaceum, Eupatorium herbaceum
Name authority (A. Gray) R. M. King & H. Robinson: Phytologia 19: 228. (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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