Flora of North America species comparison

The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Cirsium occidentale var. occidentale

Cirsium occidentale var. lucianum
Photo is of parent taxon

cobweb thistle, cobwebby thistle
Photo is of parent taxon

Cuesta Ridge thistle
Habit Plants erect, usually 30–150 cm or taller. Plants erect, 30–200 cm, densely gray-tomentose.
Leaf

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

Involucres

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

about as wide as long, 2–4 cm, floccose-arachnoid, without fine trichomes connecting tips of adjacent phyllaries.
Corollas

± bright purple, usually 25–35 mm.

dark reddish purple, 20–24 mm.
Phyllaries

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.

imbricate, outer ascending to spreading or reflexed, mid apices ascending to spreading, straight or distally curved, usually 5–8 × 1–3 mm.
Heads

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

in openly branched arrays, long-pedunculate, elevated well above proximal leaves.
2n

= 28, 29, 30.

Cirsium occidentale var. occidentale

Cirsium occidentale var. lucianum
Phenology Flowering spring–summer (Mar–Jul). Flowering spring–summer (Apr–Jul).
Habitat Coastal scrub, chaparral, oak woodlands, stabilized dunes, roadsides Chaparral, openings in closed cypress conifer forests, mixed evergreen forests, oak woodlands
Elevation 0–200 m (0–700 ft) 500–1500 m (1600–4900 ft)
Distribution
from FNA
CA
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

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.)

Variety lucianum occupies a narrow corridor along and adjacent to the main ridge of the southern Santa Lucia Mountains of San Luis Obispo County. D. J. Keil and C. E. Turner (1993) treated these plants as an atypical race of var. californicum. They resemble small-headed plants of the latter but differ in their dark, reddish purple corollas. They approach the ranges of var. californicum and var. venustum but are not known to grow with either. They may represent a stabilized emergent form derived by prehistoric hybridization between var. californicum and var. venustum.

of conservation concern

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 19, p. 137. FNA vol. 19, p. 139.
Parent taxa Asteraceae > tribe Cardueae > Cirsium > Cirsium occidentale Asteraceae > tribe Cardueae > Cirsium > Cirsium occidentale
Sibling taxa
C. occidentale var. californicum, C. occidentale var. candidissimum, C. occidentale var. compactum, C. occidentale var. coulteri, C. occidentale var. lucianum, C. occidentale var. venustum
C. occidentale var. californicum, C. occidentale var. candidissimum, C. occidentale var. compactum, C. occidentale var. coulteri, C. occidentale var. occidentale, C. occidentale var. venustum
Name authority unknown D. J. Keil: Sida 21: 214. (2004)
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).



Type/paste one or more Latin names into the boxes above; matching taxa will show up below the box as you type. You can use the up/down arrow keys to move through the list.

(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Apiaceae, Boraginaceae, and Polemoniaceae.)

Choose a data source: Flora of North America

The species comparison tool is brought to you by:
Northwest Wildflowers