FNA: Cirsium occidentale var. compactum vs. Cirsium occidentale var. occidentale

	Cirsium occidentale var. compactum	Cirsium occidentale var. occidentale
	compact cobwebby thistle	cobweb thistle, cobwebby thistle
Habit	Plants compactly branched, forming low rounded mounds, 5–100 cm, densely gray-tomentose.	Plants erect, usually 30–150 cm or taller.
Leaf	faces gray-tomentose or adaxial ± glabrate.	faces usually densely tomentose abaxially, less so and sometimes glabrate adaxially.
Involucres	wider than long, 5–8 cm diam., densely arachnoid with fine trichomes connecting tips of adjacent phyllaries.	usually wider than long, 4–5 cm diam., ± densely and persistently arachnoid with fine trichomes connecting tips of adjacent phyllaries.
Corollas	dark rose-purple, 25–30 mm.	± bright purple, usually 25–35 mm.
Phyllaries	imbricate to subequal, outer and mid apices ± spreading, straight, usually 1–2 cm × usually 1–2 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	borne singly or in ± tight clusters, short-pedunculate, closely subtended and often overtopped by basal and large cauline leaves.	usually long- pedunculate, sometimes in tight clusters at ends of peduncles, elevated well above proximal leaves.
2n	= 30.	= 28, 29, 30.

	Cirsium occidentale var. compactum	Cirsium occidentale var. occidentale
Phenology	Flowering winter–summer (Feb–Jul).	Flowering spring–summer (Mar–Jul).
Habitat	Coastal sea bluffs, dunes in grassland and coastal scrub	Coastal scrub, chaparral, oak woodlands, stabilized dunes, roadsides
Elevation	0–50 m (0–200 ft)	0–200 m (0–700 ft)
Distribution	CA [BONAP county map]	CA [BONAP county map]
Discussion	Variety compactum is locally common along the immediate coast of northern San Luis Obispo County and formerly ranged as far north as San Francisco. Populations referable to this race occur on the California Channel Islands and on the mainland in Monterey County. Because of the very narrow ecologic zone occupied by these plants they are particularly vulnerable to habitat loss. Variety compactum is closely related to vars. occidentale and coulteri. of conservation concern (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. californicum, C. occidentale var. candidissimum, 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
Name authority	Hoover: Vasc. Pl. San Luis Obispo Co., 310. (1970)	unknown
Web links	Local floras: CA Local Web sites: CalFlora, CalPhotos WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: CA Local Web sites: CalFlora, CalPhotos WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Cirsium occidentale var. compactum

Cirsium occidentale var. occidentale

compact cobwebby thistle

cobweb thistle, cobwebby thistle

Habit

Plants compactly branched, forming low rounded mounds, 5–100 cm, densely gray-tomentose.

Plants erect, usually 30–150 cm or taller.

Leaf

faces gray-tomentose or adaxial ± glabrate.

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

Involucres

wider than long, 5–8 cm diam., densely arachnoid with fine trichomes connecting tips of adjacent phyllaries.

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

Corollas

dark rose-purple, 25–30 mm.

± bright purple, usually 25–35 mm.

Phyllaries

imbricate to subequal, outer and mid apices ± spreading, straight, usually 1–2 cm × usually 1–2 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

borne singly or in ± tight clusters, short-pedunculate, closely subtended and often overtopped by basal and large cauline leaves.

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

= 30.

= 28, 29, 30.

Cirsium occidentale var. compactum

Cirsium occidentale var. occidentale

Phenology

Flowering winter–summer (Feb–Jul).

Flowering spring–summer (Mar–Jul).

Habitat

Coastal sea bluffs, dunes in grassland and coastal scrub

Coastal scrub, chaparral, oak woodlands, stabilized dunes, roadsides

Elevation

0–50 m (0–200 ft)

0–200 m (0–700 ft)

Distribution

[BONAP county map]

Discussion

Variety compactum is locally common along the immediate coast of northern San Luis Obispo County and formerly ranged as far north as San Francisco. Populations referable to this race occur on the California Channel Islands and on the mainland in Monterey County. Because of the very narrow ecologic zone occupied by these plants they are particularly vulnerable to habitat loss. Variety compactum is closely related to vars. occidentale and coulteri.

of conservation concern

(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

Sibling taxa

C. occidentale var. californicum, C. occidentale var. candidissimum, 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

Name authority

Hoover: Vasc. Pl. San Luis Obispo Co., 310. (1970)

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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Flora of North America species comparison

Cirsium occidentale var. compactum

Cirsium occidentale var. occidentale

Cirsium occidentale var. compactum

Cirsium occidentale var. occidentale