Flora of North America species comparison

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Cirsium occidentale var. californicum

Cirsium occidentale var. occidentale
Photo is of parent taxon

California thistle, cobwebby thistle
Photo is of parent taxon

cobweb thistle, cobwebby thistle
Habit Plants erect, usually 50–200 cm, thinly to densely gray-tomentose, sometimes glabrate. Plants erect, usually 30–150 cm or taller.
Leaf

faces abaxially green to gray, adaxially gray.

faces usually densely tomentose abaxially, less so and sometimes glabrate adaxially.
Involucres

usually about as wide as long, 1.5–5 cm, subglabrous to densely arachnoid.

usually wider than long, 4–5 cm diam., ± densely and persistently arachnoid with fine trichomes connecting tips of adjacent phyllaries.
Corollas

white to light purple or rose, 18–35 mm.

± bright purple, usually 25–35 mm.
Phyllaries

usually imbricate, mid apices appressed to loosely spreading or ascending, sometimes twisted, usually less than 1 cm (but sometimes much longer), 1–3 mm.

usually ± imbricate, outer ascending or spreading or reflexed, mid phyllary apices ascending to spreading, straight or distally curved, usually 1–2 cm × 1–2 mm.
Heads

in ± open clusters, short- to long-pedunculate, elevated well above proximal leaves.

usually long- pedunculate, sometimes in tight clusters at ends of peduncles, elevated well above proximal leaves.
2n

= 28, 29, 30 (as C. californicum).

= 28, 29, 30.

Cirsium occidentale var. californicum

Cirsium occidentale var. occidentale
Phenology Flowering spring–summer (Apr–Aug). Flowering spring–summer (Mar–Jul).
Habitat Pine-oak woodlands, riparian woodlands, chaparral, openings in mixed evergreen forests, roadsides Coastal scrub, chaparral, oak woodlands, stabilized dunes, roadsides
Elevation 100–2200 m (300–7200 ft) 0–200 m (0–700 ft)
Distribution
from FNA
CA
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

Variety californicum occurs in both coastal and interior mountains of California from the northern South Coast Range and the northern Sierra Nevada to the mountains of southwestern California. Considerable variation exists in head size, corolla color, and in length and display of phyllary appendages. In several areas of its range, the predominantly white- to light purple-flowered var. californicum occurs with red-flowered var. venustum. These plants are highly interfertile (H. Wells 1983; D. J. Keil and C. E. Turner 1992). Introgressive hybridization among them has resulted in a variety of emergent phenotypes and may have contributed to the variation within var. californicum.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Variety occidentale occupies a variety of habitats in the coastal zone of southern and central California. Considerable variation occurs from population to population in head size, flower color, and pubescence. It sometimes occurs together with and appears to intergrade with var. coulteri. Where there has been no hybridization, the two may be strikingly dissimilar, but individuals of some populations cannot be assigned with confidence to either variety.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 19, p. 139. FNA vol. 19, p. 137.
Parent taxa Asteraceae > tribe Cardueae > Cirsium > Cirsium occidentale Asteraceae > tribe Cardueae > Cirsium > Cirsium occidentale
Sibling taxa
C. occidentale var. candidissimum, C. occidentale var. compactum, C. occidentale var. coulteri, C. occidentale var. lucianum, C. occidentale var. occidentale, C. occidentale var. venustum
C. occidentale var. californicum, C. occidentale var. candidissimum, C. occidentale var. compactum, C. occidentale var. coulteri, C. occidentale var. lucianum, C. occidentale var. venustum
Synonyms C. californicum, C. bernardinum, C. californicum var. bernardinum, C. californicum subsp. pseudoreglense
Name authority (A. Gray) D. J. Keil & C. E. Turner: Phytologia 73: 315. (1992) unknown
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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