Cirsium occidentale | |
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Flower head of Cirsium occidentale | |
Scientific classification
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Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Asterales |
Family: | Asteraceae |
Genus: | Cirsium |
Species: | C. occidentale
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Binomial name | |
Cirsium occidentale | |
Synonyms [2] | |
Cirsium coulteri |
Cirsium occidentale, with the common name cobweb thistle or cobwebby thistle, is a North American species of thistle in the family Asteraceae. [3]
Cirsium occidentale is a biennial plant or perennial plant forming a taproot. It may be short or quite tall, forming low clumps or towering to heights approaching 3 meters (10 feet). The leaves are dull gray-green to bright white due to a coating of hairs, and the most basal ones on large plants may be nearly 0.5 m (1+1⁄2 ft) in length. [4] [3] The petioles are winged and spiny and the leaves are toothed or edged with triangular lobes. [5]
The inflorescence at the top of the whitish stem holds one to several flower heads. Each head is sphere-like, covered in large phyllaries with very long, spreading spines which are laced, often quite heavily, in fibers resembling cobwebs. [5]
The head is packed with disc florets which may be white to blood red to shades of purple. The largest flower heads exceed 8 centimeters (3 inches) in diameter. [4] The heads do not open in synchrony, perhaps allowing greater likelihood of being pollinated. [5]
There are several varieties, which differ from each other in range and form: [4]
The plant is widespread and fairly common across most of California: in its mountain ranges, valleys, and the Mojave Desert; and in the western Great Basin region in western Nevada, southern Oregon, and southwestern Idaho. [15] [4] [16]
Unlike many introduced thistles, this native species is not a troublesome weed.
It is a larval host to the California crescent, mylitta crescent, and the painted lady butterfly. [17]
Cirsium occidentale | |
---|---|
![]() | |
Flower head of Cirsium occidentale | |
Scientific classification
![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Asterales |
Family: | Asteraceae |
Genus: | Cirsium |
Species: | C. occidentale
|
Binomial name | |
Cirsium occidentale | |
Synonyms [2] | |
Cirsium coulteri |
Cirsium occidentale, with the common name cobweb thistle or cobwebby thistle, is a North American species of thistle in the family Asteraceae. [3]
Cirsium occidentale is a biennial plant or perennial plant forming a taproot. It may be short or quite tall, forming low clumps or towering to heights approaching 3 meters (10 feet). The leaves are dull gray-green to bright white due to a coating of hairs, and the most basal ones on large plants may be nearly 0.5 m (1+1⁄2 ft) in length. [4] [3] The petioles are winged and spiny and the leaves are toothed or edged with triangular lobes. [5]
The inflorescence at the top of the whitish stem holds one to several flower heads. Each head is sphere-like, covered in large phyllaries with very long, spreading spines which are laced, often quite heavily, in fibers resembling cobwebs. [5]
The head is packed with disc florets which may be white to blood red to shades of purple. The largest flower heads exceed 8 centimeters (3 inches) in diameter. [4] The heads do not open in synchrony, perhaps allowing greater likelihood of being pollinated. [5]
There are several varieties, which differ from each other in range and form: [4]
The plant is widespread and fairly common across most of California: in its mountain ranges, valleys, and the Mojave Desert; and in the western Great Basin region in western Nevada, southern Oregon, and southwestern Idaho. [15] [4] [16]
Unlike many introduced thistles, this native species is not a troublesome weed.
It is a larval host to the California crescent, mylitta crescent, and the painted lady butterfly. [17]