Ageratina rothrockii

(A. Gray) R. M. King & H. Robinson

Phytologia 19: 216. 1970.

Common names: Rothrock’s snakeroot
Basionyms: Eupatorium rothrockii A. Gray in A. Gray et al., Syn. Fl. N. Amer. 1(2): 102. 1884
Treatment appears in FNA Volume 21. Treatment on page 550. Mentioned on page 548.

Perennials, (20–) 40–70 (–150) cm (slender, fibrous-rooted crowns, with slender rhizomes). Stems ascending to erect, puberulent to glabrate. Leaves opposite; petioles 2–20 mm; blades (3–5-nerved) lanceolate to lanceolate-ovate, mostly 3–6 × (1.5–) 2–3 cm, bases obtuse to truncate, margins serrate to crenate, apices acute to acuminate, sparsely puberulent abaxially, mostly along nerves. Heads clustered. Peduncles 5–12 (–20) mm, puberulent. Involucres 5–7 mm. Phyllaries: apices acute, abaxial faces glabrous or glabrescent, eglandular. Corollas white, lobes short-villous. Cypselae sparsely and finely strigose-hirsute. 2n = 85 [ca. 100, fide A. M. Powell on label].


Phenology: Flowering (Jul–)Aug–Oct.
Habitat: Rocky slopes and ledges, in oak-juniper, pine-oak, pine, aspen, and spruce-fir woodland
Elevation: 1700–2400 m

Distribution

V21-1393-distribution-map.gif

Ariz., N.Mex., Tex., Mexico (Chihuahua), Mexico (Coahuila), Mexico (Durango), Mexico (Sonora)

Discussion

Ageratina rothrockii is similar to A. altissima, probably its western vicariant, and the two perhaps would be justifiably treated as conspecific.

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

... more about "Ageratina rothrockii"
glabrescent +  and glabrous +
not tailed +, truncate +, rounded +  and obtuse +
puberulent +
scarious +
usually ovate +  and lanceolate +
usually terete +  and clavate +
indeterminate +  and determinate +
Guy L. Nesom +
(A. Gray) R. M. King & H. Robinson +
obtuse to truncate +
enlarged +
Eupatorium rothrockii +
3(-5)-nerved +
1.5 cm15 mm <br />0.015 m <br /> (2 cm20 mm <br />0.02 m <br />) +
3 cm30 mm <br />0.03 m <br /> (6 cm60 mm <br />0.06 m <br />) +
dissected +, lobed +, toothed +  and entire +
lanceolate;lanceolate-ovate +
2cm;3cm +
papillate +  and rugose +
(4-)5-angled;10-ribbed +
Rothrock’s snakeroot +
strigose-hirsute +
scabrellous +
fusiform +  and prismatic +
fertile +  and bisexual +
Ariz. +, N.Mex. +, Tex. +, Mexico (Chihuahua) +, Mexico (Coahuila) +, Mexico (Durango) +  and Mexico (Sonora) +
1700–2400 m +
puberulent +, pilose +, hispidulous +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Rocky slopes and ledges, in oak-juniper, pine-oak, pine, aspen, and spruce-fir woodland +
indeterminate +
each +  and sessile +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
campanulate +
0.5 cm5 mm <br />0.005 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
short-villous +
lanceolate +  and lance-linear +
serrate +, dentate +  and entire +
serrate +  and crenate +
2-carpellate +
persistent +
1.2 cm12 mm <br />0.012 m <br /> (2 cm20 mm <br />0.02 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (2 cm20 mm <br />0.02 m <br />) +
Flowering (Jul–)Aug–Oct. +
2-nerved +  and 0-nerved +
8 +  and 30 +
subequal +  and unequal +
bearing subulate enations +, hairy +  and bristly +
exalbuminous +
ascending +  and erect +
appendaged +  and truncate +
hirsutulous +
papillate +
Compositae +
Ageratina rothrockii +
Ageratina +
species +
obconic +  and campanulate +
70 cm700 mm <br />0.7 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +
40 cm400 mm <br />0.4 m <br /> (70 cm700 mm <br />0.7 m <br />) +
shrub +  and subshrub +