Flora of North America species comparison

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Cirsium occidentale var. californicum
Photo is of parent taxon

California thistle, cobwebby thistle
Habit Plants erect, usually 50–200 cm, thinly to densely gray-tomentose, sometimes glabrate.
Leaf

faces abaxially green to gray, adaxially gray.
Involucres

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

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

in ± open clusters, short- to long-pedunculate, elevated well above proximal leaves.
2n

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

Cirsium occidentale var. californicum
Phenology Flowering spring–summer (Apr–Aug).
Habitat Pine-oak woodlands, riparian woodlands, chaparral, openings in mixed evergreen forests, roadsides
Elevation 100–2200 m (300–7200 ft)
Distribution
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.)
Source FNA vol. 19, p. 139.
Parent taxa 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
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)
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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