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Cirsium occidentale is a species of thistle known by the common name cobwebby thistle. This plant may be short or quite tall, forming low clumps or towering to heights approaching 3 meters. 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 half a meter 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 somewhat spherical, 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 in diameter. This eyecatching plant is native to western North America. There are several varieties which differ from each other, for example, the compact cobwebby thistle, var. compactum, is a short, clumpy plant which grows only along the Central Coast of California. Unlike many other thistles, this species tends not to be a troublesome weed.
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