Flora of North America species comparison

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Ageratina wrightii

Ageratina shastensis

Wright's snakeroot

Mt. Shasta snakeroot, Shasta ageratina, Shasta snakeroot
Habit Shrubs, 50–150 cm. Perennials, 15–45 cm (bases woody, enlarged, occasionally rhizomatous).
Stems

erect, puberulous.

erect (clustered from bases), puberulent to pubescent (often with some glandular hairs distally).
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 proximally, alternate on at least distal 1/2 of stems;

petioles 4–6 mm;

blades (venation raised-reticulate) orbiculate (juvenile) or deltate-ovate, 1.5–3 × 1–2 cm, (subcoriaceous) bases obtuse to truncate, margins entire or coarsely serrate to dentate, apices acute to acuminate, abaxial faces ± gland-dotted and/or stipitate-glandular.
Peduncles

1–3 mm, puberulent.

(0–)2–15 mm, puberulent and stipitate-glandular.
Involucres

3.5–4.5 mm.

10–11 mm.
Corollas

pinkish white to pink, glabrous.

white, glabrous.
Phyllaries

apices acute, abaxial faces puberulent.

apices acute, abaxial faces sparsely puberulent.
Heads

clustered.

mostly borne singly (each often subtended by a leaflike bract).
Cypselae

sparsely hispidulous.

hispidulous.
2n

= 34.

Ageratina wrightii

Ageratina shastensis
Phenology Flowering (Jul–)Aug–Oct(–Nov). Flowering Jun–Oct.
Habitat Limestone slopes, ledges, alluvium, in brushy vegetation Cracks and crevices of nearly vertical limestone cliffs
Elevation 1300–2200 m (4300–7200 ft) 400–1800 m (1300–5900 ft)
Distribution
from FNA
AZ; NM; TX; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

Ageratina shastensis is recognized by relatively large solitary heads and coarsely serrate, subcoriaceous leaves alternate on distal parts of stems.

(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. occidentalis, A. paupercula, A. rothrockii, A. shastensis, A. thyrsiflora
A. adenophora, A. altissima, A. aromatica, A. havanensis, A. herbacea, A. jucunda, A. lemmonii, A. luciae-brauniae, A. occidentalis, A. paupercula, A. rothrockii, A. thyrsiflora, A. wrightii
Synonyms Eupatorium wrightii Eupatorium shastense
Name authority (A. Gray) R. M. King & H. Robinson: Phytologia 19: 228. (1970) (D. W. Taylor & Stebbins) R. M. King & H. Robinson: Phytologia 45: 464. (1980)
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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