Ageratina occidentalis

(Hooker) R. M. King & H. Robinson

Phytologia 19: 224. 1970.

Common names: Western snakeroot
IllustratedEndemic
Basionym: Eupatorium occidentale Hooker Fl. Bor.-Amer. 1: 305. 1833
Treatment appears in FNA Volume 21. Treatment on page 552. Mentioned on page 547, 548.
Revision as of 21:59, 29 July 2020 by imported>Volume Importer
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Perennials or subshrubs, 15–70 cm (caudices woody, rhizomatous). Stems (green or purple) erect or ascending, puberulent. Leaves opposite proximally, alternate on distal 1/4–1/2 of stems; petioles 5–12 mm; blades triangular to ovate, 2.5–5 × 1.7–4 cm, bases truncate to cuneate, margins serrate, apices acute, abaxial faces glanddotted. Heads clustered. Peduncles 2–5 mm, minutely puberulent. Involucres 3–3.5 (–4) mm. Phyllaries: apices acute, abaxial faces viscid-puberulent and/or sessile-glandular. Corollas pink, bluish, or white tinged with purple, lobes glabrous or glabrate. Cypselae sessile-glandular. 2n = 34.


Phenology: Flowering (Jun–)Jul–Sep.
Habitat: Crevices, outcrops, rocky slopes, ridges, talus, gravelly and sandy stream bars, mixed hardwood-conifer woodlands, aspen, open and brushy vegetation
Elevation: (40–50)900–2800(–3200) m

Distribution

V21-1402-distribution-map.gif

Calif., Idaho, Mont., Nev., Oreg., Utah, Wash.

Discussion

Ageratina occidentalis is the only species of the genus in the flora area with sessile-glandular cypselae; peduncles also may be sessile-glandular. Its identity also can be confirmed among flora area species by its relatively long (5–6 mm) corollas.

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

... more about "Ageratina occidentalis"
sessile-glandular +  and viscid-puberulent +
not tailed +, truncate +, rounded +  and obtuse +
acute;acute +
scarious +
usually ovate +  and lanceolate +
usually terete +  and clavate +
indeterminate +  and determinate +
Guy L. Nesom +
(Hooker) R. M. King & H. Robinson +
truncate +  and cuneate +
enlarged +
Eupatorium occidentale +
3(-5)-nerved +
2.5 cm25 mm <br />0.025 m <br /> (5 cm50 mm <br />0.05 m <br />) +
dissected +, lobed +, toothed +  and entire +
triangular;ovate +
1.7 cm17 mm <br />0.017 m <br /> (4 cm40 mm <br />0.04 m <br />) +
papillate +  and rugose +
(4-)5-angled;10-ribbed +
Western snakeroot +
white tinged with purple +, bluish +  and pink +
scabrellous +
fusiform +  and prismatic +
fertile +  and bisexual +
Calif. +, Idaho +, Mont. +, Nev. +, Oreg. +, Utah +  and Wash. +
(40–50)900–2800(–3200) m +
puberulent +, pilose +, hispidulous +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Crevices, outcrops, rocky slopes, ridges, talus, gravelly and sandy stream bars, mixed hardwood-conifer woodlands, aspen, open and brushy vegetation +
indeterminate +
each +  and sessile +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
campanulate +
0.3 cm3 mm <br />0.003 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
alternate +  and opposite +
glabrate +  and glabrous +
lanceolate +  and lance-linear +
2-carpellate +
persistent +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
Flowering (Jun–)Jul–Sep. +
2-nerved +  and 0-nerved +
8 +  and 30 +
subequal +  and unequal +
bearing subulate enations +, hairy +  and bristly +
exalbuminous +
Illustrated +  and Endemic +
ascending +  and erect +
puberulent +
appendaged +  and truncate +
hirsutulous +
papillate +
Compositae +
Ageratina occidentalis +
Ageratina +
species +
obconic +  and campanulate +
15 cm150 mm <br />0.15 m <br /> (70 cm700 mm <br />0.7 m <br />) +