page_title: Cirsium occidentale
section_title: Description
hierarchical_section_title: Cirsium occidentale / Description
caption_attribution_description: English: Photographed at Abbott's Lagoon, Pt. Reyes National Seashore, Marin County, California
context_page_description: Cirsium occidentale, with the common name cobweb thistle or cobwebby thistle, is a North American species of thistle in the sunflower family.
context_section_description: Cirsium occidentale is a biennial forming a taproot. It may be short or quite tall, forming low clumps or towering to heights approaching 3 meters (9.8 ft). 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 meters (1.6 ft) in length. The petioles are winged and spiny and the leaves are toothed or edged with triangular lobes.
  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.
  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 (3.1 in) in diameter. The heads do not open in synchrony, perhaps allowing greater likelihood of being pollinated.
caption: Flower with seed head forming (Cirsium occidentale var. occidentale)
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