Flora of North America species comparison

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Cirsium occidentale var. coulteri
Photo is of parent taxon

Coulter's thistle
Habit Plants erect or bushy, usually 30–150+ cm, variably tomentose, sometimes ± glabrate.
Leaf

faces gray-tomentose or adaxial ± glabrate.
Involucres

usually about as wide as tall, 4–5 cm diam., densely arachnoid with fine trichomes connecting tips of adjacent phyllaries.
Corollas

light purple to rich reddish purple, usually 25–33 mm.
Phyllaries

subequal, outer ascending to spreading or reflexed, mid apices ascending to stiffly spreading, straight, acicular, usually 1.5–3 × 1–2 mm.
Heads

sometimes in tight clusters at ends of peduncles, usually long-pedunculate, usually elevated well above proximal leaves.

Cirsium occidentale var. coulteri
Phenology Flowering spring–summer (Mar–Jun).
Habitat Coastal slopes and ridges, dunes, coastal scrub, grassland, oak woodlands
Elevation 0–700 m (0–2300 ft)
Distribution
from FNA
CA
[BONAP county map]
Discussion

Of conservation concern.

Variety coulteri grows in the coastal zone of central and southern California. The epithet coulteri was for many years misapplied by California botanists. W. L. Jepson ([1923–1925]) used it at the varietal level for a range of plants that included parts of what I am calling vars. venustum and californicum. P. A. Munz (1959) and various other authors recognized Cirsium coulteri as a species, primarily in the context that I recognize as var. venustum. J. T. Howell (1959b) examined the type of C. coulteri and concluded that it and C. occidentale (in the strict sense) are synonymous. I have examined photos of the types of both C. occidentale and C. coulteri and have reached a different conclusion. The type of C. occidentale (BM) has heads with ± imbricate, comparatively short phyllary appendages. The type of C. coulteri (TCD) has long, acicular, subequal phyllaries. D. J. Keil and C. E. Turner (1993) treated the plants with the two head types all as var. occidentale, but I believe it is preferable to recognize separate varieties. Some intermediates are known, but var. coulteri is usually readily separable from var. occidentale.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 19, p. 138.
Parent taxa Asteraceae > tribe Cardueae > Cirsium > Cirsium occidentale
Sibling taxa
C. occidentale var. californicum, C. occidentale var. candidissimum, C. occidentale var. compactum, C. occidentale var. lucianum, C. occidentale var. occidentale, C. occidentale var. venustum
Synonyms C. coulteri
Name authority (Harvey & A. Gray) Jepson: Fl. W. Calif., 509. (1901)
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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