Cirsium arizonicum var. rothrockii

(A. Gray) D. J. Keil

Sida 21: 210. 2004.

Common names: Rothrock’s thistle
Endemic
Basionym: Cnicus rothrockii A. Gray Proc. Amer. Acad. Arts 17: 220. 1882
Synonyms: Cirsium rothrockii (A. Gray) Petrak
Treatment appears in FNA Volume 19. Treatment on page 143. Mentioned on page 142.

Stems glabrous. Leaf-blades ± deeply divided or the distal unlobed and merely spiny-dentate, faces glabrous or the basal abaxially sometimes thinly tomentose, rarely with septate trichomes abaxially along the midveins; main marginal spines often stout, 5–15 mm; cauline bases usually narrowed, not decurrent. Involucres cylindric to narrowly ovoid. Phyllary spines slender to very stout, 5–30 mm. Corollas bright red, 28–32 mm, tubes 10–12, throats 1.5–3 mm, lobes 15–17 mm; style tips 1–2.5 mm. 2n = 30 (as C. rothrockii).


Phenology: Flowering summer–fall (Jun–Oct).
Habitat: Rocky slopes, embankments, pine-oak-juniper-cypress woodlands, montane coniferous forests
Elevation: 1500–2800 m

Discussion

Variety rothrockii is endemic to Chiricahua, Dos Cabseos, Huachuca, Peloncillo, Pinal, Pinaleno, Sierra Ancha, and White mountains of southeastern Arizona and adjacent New Mexico, where it largely replaces var. arizonicum. The name Cirsium rothrockii has been misapplied to similarly glabrous plants of the Four Corners region (e.g., S. L. Welsh 1983), but those plants are assigned here to other varieties.

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

glabrous +  and densely gray tomentose +
glabrate +, glabrous +  and gray-tomentose +
short-tailed +
spineless +  and twisted +
spreading +  and ascending +
innermost +
inconspicuous +
scarious +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
paniculiform +  and corymbiform +
indeterminate +  and determinate +
David J. Keil +
(A. Gray) D. J. Keil +
sessile +  and winged-petiolate +
decurrent +
Cnicus rothrockii +
compound +  and simple +
3 cm30 mm <br />0.03 m <br /> (40 cm400 mm <br />0.4 m <br />) +
spinulose;shallowly lobed or divided +
1cm;13cm +
with straight or flexuous spines +  and unarmed +
10-nerved or 20-nerved +  and rugose +
tawny +  and white +
? (?) +  and ? (?) +
not decurrent +  and narrowed +
Rothrock’s thistle +
actinomorphic +
2.8 cm28 mm <br />0.028 m <br /> (3.2 cm32 mm <br />0.032 m <br />) +
compressed +  and ovoid +
fertile +  and bisexual +
Ariz. +  and N.Mex. +
1500–2800 m +
tomentose +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Rocky slopes, embankments, pine-oak-juniper-cypress woodlands, montane coniferous forests +
indeterminate +
each +  and sessile +
1.5 cm15 mm <br />0.015 m <br /> (4 cm40 mm <br />0.04 m <br />) +
glabrous +  and arachnoid +
cylindric;narrowly ovoid +
1 cm10 mm <br />0.01 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
sessile +  and petiolate +
cauline +  and basal +
bristle-tipped +
divided +, lobed +, ovate +  and linear-acuminate +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (3 cm30 mm <br />0.03 m <br />) +
usually lobed +  and dissected +
2-carpellate +
persistent +
1.7 cm17 mm <br />0.017 m <br /> (2.8 cm28 mm <br />0.028 m <br />) +
0 cm0 mm <br />0 m <br /> (15 cm150 mm <br />0.15 m <br />) +
Flowering summer–fall (Jun–Oct). +
middle +  and outer +
weakly to strongly +
slender to very +
0.5 cm5 mm <br />0.005 m <br /> (3 cm30 mm <br />0.03 m <br />) +
papillate +  and smooth +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
glutinous +
inconspicuous +
tawny;white +
setiform +  and plumose +
exalbuminous +
subequal +
flexuous +  and straight +
erect +  and reflexed +
flattened +  and cylindric +
Slender (?) +  and Stout (?) +
0.1 cm1 mm <br />0.001 m <br /> (3 cm30 mm <br />0.03 m <br />) +
spiny-winged +, simple +  and branched +
ascending +  and erect +
1 +  and several +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
0.1 cm1 mm <br />0.001 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
Cirsium rothrockii +
Cirsium arizonicum var. rothrockii +
Cirsium arizonicum +
variety +
cylindric +
expanded +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
bristly-dentate to coarsely +
slender +
0.7 cm7 mm <br />0.007 m <br /> (1.25 cm12.5 mm <br />0.0125 m <br />) +
30 cm300 mm <br />0.3 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +
tree +, vine +, shrub +  and subshrub +
0 cm0 mm <br />0 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +