Cobweb Thistle, Cirsium occidentale

About Cobweb Thistle (Cirsium occidentale) 15 Nurseries Carry This Plant

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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 flower cluster 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.

Plant Description

Plant Type

Perennial herb

Size

2 - 10 ft tall

Flower Color

Red, Purple, Pink, White

Flowering Season

Spring, Summer

Wildlife Supported

Butterflies & moths hosted ( 17 likely * ) SHOW ALL

Painted Lady Vanessa carduiVanessa cardui

Mylitta Crescent Phyciodes mylittaPhyciodes mylitta

California Crescent Phyciodes orseisPhyciodes orseis

White-lined Sphinx Hyles lineataHyles lineata

Bilobed Looper Moth Megalographa bilobaMegalographa biloba

Sweetclover Root Borer Moth Walshia miscecolorellaWalshia miscecolorella

Garden Webworm Moth Achyra rantalisAchyra rantalis

Landscaping Information

Sun

Full Sun, Part Shade

Nurseries

Carried by 15

Ease of Care

Moderately Easy

Soil Drainage

Fast, Medium, Slow

Soil Description

Adaptable

Common uses

Deer Resistant, Butterfly Gardens

Natural Setting

Site Type

Varied

Climate

Annual Precipitation: 4.0" - 135.9", Summer Precipitation: 0.13" - 3.95", Coldest Month: 19.6" - 57.4", Hottest Month: 41.1" - 84.5", Humidity: 0.36" - 36.04", Elevation: -30" - 11398"

Alternative Names

Common Names: Cobwebby Thistle, Western Thistle

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Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links: Jepson eFlora Taxon Page CalPhotos Wikipedia Calflora

Cobweb Thistle

Cirsium occidentale

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Cobweb ThistleCirsium occidentale

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Cobweb Thistle

Cirsium occidentale