Flora of North America species comparison

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Ageratina paupercula

Ageratina shastensis

Santa Rita snakeroot

Mt. Shasta snakeroot, Shasta ageratina, Shasta snakeroot
Habit Perennials or subshrubs, to 100 cm. Perennials, 15–45 cm (bases woody, enlarged, occasionally rhizomatous).
Stems

erect, puberulent to glabrate.

erect (clustered from bases), puberulent to pubescent (often with some glandular hairs distally).
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 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

2–6 mm, puberulent.

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

2.5–3 mm.

10–11 mm.
Corollas

white, lobes sparsely hispid-villous.

white, glabrous.
Phyllaries

apices acute, abaxial faces puberulent-hispidulous.

apices acute, abaxial faces sparsely puberulent.
Heads

clustered.

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

glabrous.

hispidulous.
2n

= 34.

Ageratina paupercula

Ageratina shastensis
Phenology Flowering Mar–May. Flowering Jun–Oct.
Habitat Rocky slopes, crevices, gravelly, sandy streambeds, pine-oak woodlands Cracks and crevices of nearly vertical limestone cliffs
Elevation 1000–1800 m (3300–5900 ft) 400–1800 m (1300–5900 ft)
Distribution
from FNA
AZ; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[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.)

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. 551. 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. 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. thyrsiflora, A. wrightii
Synonyms Eupatorium pauperculum Eupatorium shastense
Name authority (A. Gray) R. M. King & H. Robinson: Phytologia 19: 215. (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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