Flora of North America species comparison

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Ageratina havanensis

Ageratina shastensis

Havana snakeroot, shrubby boneset, white mistflower, white shrub mistflower

Mt. Shasta snakeroot, Shasta ageratina, Shasta snakeroot
Habit Shrubs [trees], (30–)69–150(–200) cm. Perennials, 15–45 cm (bases woody, enlarged, occasionally rhizomatous).
Stems

erect (brittle), puberulent to glabrous.

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

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.

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

2–14 mm, minutely puberulent.

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

4–6 mm.

10–11 mm.
Corollas

white to slightly pinkish, glabrous.

white, glabrous.
Phyllaries

apices acute, abaxial faces glabrous or nearly so.

apices acute, abaxial faces sparsely puberulent.
Heads

clustered.

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

hispid.

hispidulous.
2n

= 34.

= 34.

Ageratina havanensis

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

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.)

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. herbacea, A. jucunda, A. lemmonii, A. luciae-brauniae, A. occidentalis, A. paupercula, 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 havanense Eupatorium shastense
Name authority (Kunth) R. M. King & H. Robinson: Phytologia 19: 222. (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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