Flora of North America species comparison

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Ageratina shastensis

Ageratina havanensis

Mt. Shasta snakeroot, Shasta ageratina, Shasta snakeroot

Havana snakeroot, shrubby boneset, white mistflower, white shrub mistflower
Habit Perennials, 15–45 cm (bases woody, enlarged, occasionally rhizomatous). Shrubs [trees], (30–)69–150(–200) cm.
Stems

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

erect (brittle), puberulent to glabrous.
Leaves

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.

persistent, opposite;

petioles 3–10(–15) mm;

blades deltate to broadly ovate or somewhat hastate, (2–)3–5(–8) × 2–5 cm, bases truncate to cuneate, margins dentate, apices acute, faces glabrous or nearly so, eglandular.
Peduncles

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

2–14 mm, minutely puberulent.
Involucres

10–11 mm.

4–6 mm.
Corollas

white, glabrous.

white to slightly pinkish, glabrous.
Phyllaries

apices acute, abaxial faces sparsely puberulent.

apices acute, abaxial faces glabrous or nearly so.
Heads

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

clustered.
Cypselae

hispidulous.

hispid.
2n

= 34.

= 34.

Ageratina shastensis

Ageratina havanensis
Phenology Flowering Jun–Oct. Flowering mainly (Sep–)Oct–Nov(–Dec), also Apr–Jul.
Habitat Cracks and crevices of nearly vertical limestone cliffs Bluffs, limestone outcrops and slopes, ledges along streams, often in oak-juniper woodlands
Elevation 400–1800 m (1300–5900 ft) 100–900 m (300–3000 ft)
Distribution
from FNA
CA
[BONAP county map]
from FNA
TX; Mexico; West Indies (Cuba)
[WildflowerSearch map]
[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.)

Ageratina havanensis apparently is the only species of the genus in the flora area with evergreen-persistent leaves.

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