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Rothrock's snakeroot

Habit Perennials, (20–)40–70(–150) cm (slender, fibrous-rooted crowns, with slender rhizomes).
Stems

ascending to erect, puberulent to glabrate.

Leaves

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(–20) mm, puberulent.

Involucres

5–7 mm.

Corollas

white, lobes short-villous.

Phyllaries

apices acute, abaxial faces glabrous or glabrescent, eglandular.

Heads

clustered.

Cypselae

sparsely and finely strigose-hirsute.

Powell

on label].

2n

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

Ageratina rothrockii

Phenology Flowering (Jul–)Aug–Oct.
Habitat Rocky slopes and ledges, in oak-juniper, pine-oak, pine, aspen, and spruce-fir woodland
Elevation 1700–2400 m (5600–7900 ft)
Distribution
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. 550.
Parent taxa 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. shastensis, A. thyrsiflora, A. wrightii
Synonyms Eupatorium rothrockii
Name authority (A. Gray) R. M. King & H. Robinson: Phytologia 19: 216. (1970)
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