Cirsium arizonicum var. bipinnatum

(Eastwood) D. J. Keil

Sida 21: 209. 2004.

Common names: Four Corners thistle
Endemic
Basionym: Cnicus drummondii var. bipinnatus Eastwood Zoë 4: 8. 1893
Synonyms: Cirsium bipinnatum (Eastwood) Rydberg Cirsium calcareum (M. E. Jones) Wooton & Standley Cirsium calcareum var. bipinnatum (Eastwood) S. L. Welsh Cirsium calcareum var. pulchellum (Greene ex Rydberg) S. L. Welsh Cirsium diffusum Cirsium pulchellum Cirsium pulchellum subsp. bipinnatum (Eastwood) Petrak Cirsium pulchellum subsp. diffusum (Eastwood) Petrak Cirsium pulchellum var. glabrescens Petrak
Treatment appears in FNA Volume 19. Treatment on page 143. Mentioned on page 142.

Stems glabrous to tomentose, usually without septate trichomes. Leaf blades unlobed to deeply divided, faces glabrous to tomentose on one or both, usually without septate trichomes; main marginal spines slender to stout, 3–10 mm; cauline bases narrowed to truncate or clasping or decurrent as spiny wings to 30 mm. Involucres cylindric or ovoid to campanulate; spines of mid phyllaries 1–6 mm, slender to very stout. Corollas usually lavender to purple or reddish purple, 22–34 mm, tubes 7–12, throats 4–9 mm, lobes 8–18 mm; style tips 1.2–4.5 mm.


Phenology: Flowering spring–summer (May–Oct).
Habitat: Canyons, rocky slopes, desert scrub, pine-oak-juniper woodlands, openings in montane coniferous forests
Elevation: 900–3100 m

Distribution

V19-127-distribution-map.gif

Ariz., Colo., N.Mex., Utah.

Discussion

Variety bipinnatum grows in the Colorado Plateau of New Mexico, northeastern Arizona, southeastern Utah, and southwestern Colorado south to the Sacramento Mountains of southern New Mexico. It is a polymorphic assemblage of races and local populations with overlapping patterns of variation. Extremes are diverse and strikingly different, and various authors have attempted to segregate variants as species, subspecies, or varieties. Apparently independent segregation of character states of multiple variable characters has resulted in a complex array of local morphotypes. Leaves range from wholly glabrous to densely tomentose on one or both faces. The bases of cauline leaves vary from sessile and not at all decurrent to prominently decurrent with spiny wings to 3 cm. Leaf lobing and spininess are similarly variable. Heads may be solitary at the branch tips or densely clustered. I have been unable to detect patterns that can consistently separate the many forms in any meaningful way.

Selected References

None.

Lower Taxa

None.
David J. Keil +
(Eastwood) D. J. Keil +
Cnicus drummondii var. bipinnatus +
Four Corners thistle +
Ariz. +, Colo. +, N.Mex. +  and Utah. +
900–3100 m +
Canyons, rocky slopes, desert scrub, pine-oak-juniper woodlands, openings in montane coniferous forests +
Flowering spring–summer (May–Oct). +
Cirsium bipinnatum +, Cirsium calcareum +, Cirsium calcareum var. bipinnatum +, Cirsium calcareum var. pulchellum +, Cirsium diffusum +, Cirsium pulchellum +, Cirsium pulchellum subsp. bipinnatum +, Cirsium pulchellum subsp. diffusum +  and Cirsium pulchellum var. glabrescens +
Cirsium arizonicum var. bipinnatum +
Cirsium arizonicum +
variety +