Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

Home to the plants of the Sonoran, Chihuahuan and Mojave Deserts

Cirsium ochrocentrum, Yellowspine Thistle

Cirsium arizonicum, Arizona Thistle

Arizona Thistle is red-flowered North American thistle that blooms from May to October or November. Flower colors are variable and range from red to pink, to purple or lavender. Cirsium arizonicum Arizona Thistle has flowers attractive to hummingbirds, bees and a variety of insects. Note young grasshopper in photo. Cirsium arizonicum Arizona Thistle bud showing variable green phyllaries or bracts, ovate or lanceolate. Cirsium arizonicum    Arizona Thistle is a large subshrub with 1 or more stems. Note whitish or tomentose stem below flower. Cirsium arizonicum Arizona Thistle leaves are also variable. Note in photo leaves are clasping at stem. Cirsium arizonicum     Arizona Thistle has small dry indehiscent fruits; photo shows tan pappus. Cirsium arizonicum Arizona Thistle is found in upper deserts in elevations from 3,000 to 7,000 feet. Habitat preferences include pine, pinyon-juniper and chaparral communities; sunny open areas, woodland opening and rocky slopes. Cirsium arizonicum     Arizona Thistle; leaves sessile, 4 to 8 inches; some lobed, tomentose, spiny throughout. Under side of leaf in photo shows the whitish or tomentose texture. Cirsium arizonicum

Scientific Name: Cirsium arizonicum
Common Name: Arizona Thistle

Also called: Spanish: Cardo Santo

Family: Asteraceae, Sunflower Family

Synonyms: (Cirsium arizonicum var. arizonicum, Cirsium arizonicum var. nidulum, Cirsium nidulum, Cnicus arizonicus)

Status: Native

Duration: Perennial or biennial.

Size: Up to 4 feet (30-150-cm) or more in height.

Growth Form: Forb/herb; spiny all over, basal rosette with 1 or more stems, erect or ascending, tomentose or glabrous; stems woolly to cobwebby.

Leaves: Green; basal leaves sessile, 4 to 8 inches, some lobed, tomentose, spiny; cauline leaves alternate; leaf shape variable, linear, elliptic or oblong, sharply toothed, upper leaves more glabrous, clasping, spines along margins.

Flower Color: Red, pink, purple or lavender (rarely white); 1 to 100 erect heads; disk florets only; corolla tube shaped; phyllaries ovate or lanceolate; fruit is a cypsela often mistaken as an achene.

Flowering Season: May to October or November

Elevation: 3,000 to 12,000 feet (900-3,600 m)

Habitat Preferences: Sunny open areas, woodland openings and rocky slopes; wide variety of upland habitats; upper deserts, pine, pinyon-juniper and chaparral communities.

Recorded Range: Arizona Thistle is found in the southwestern United States in AZ, CA, NM, NV and UT. In Arizona, it is found in higher elevations in the northern and southern parts of the state. It is also native to northwest Mexico.

North America & US County Distribution Map for Cirsium arizonicum.

Threatened/Endangered Information: Cirsium arizonicum var. tenuisectum, Desert Mountain Thistle is listed by California Rare Plant Rank: as 1B.2 Rare or endangered in California and elsewhere; .2: Fairly endangered in California
Note: This variety is Known in California only from the New York Mountains of San Bernardino County. The name Cirsium nidulum has long been misapplied to this species. May be distinctive enough to be its own taxon and not a variety of Cirsium arizonicum

U.S. Weed Information: No data available

Invasive/Noxious Weed Information: In North America the genus Cirsium is listed as a Noxious Weed by the States of Arkansas and Iowa. Plants included here are invasive or noxious. ∗ See Comments section below.

Wetland Indicator: In North America Cirsium arizonicum has the following wetland designations: Arid West, FACU; Great Plains and Western Mountains, Valleys, and Coast, FAC.
FAC = Facultative, occur in wetlands and non-wetlands
FACU = Facultative Upland, usually occur in non-wetlands, but may occur in wetlands

Genus Information: In North America there are 91 species for Cirsium. Worldwide, The Plant List includes 481 accepted species names and a further 812 scientific names of infraspecific rank for the genus. The genus Cirsium was published by Philip Miller in 1754.

In the Southwestern United States: Arizona and New Mexico each have 19 species of genus, California has 27 species, Nevada has 16 species, Texas has 12 species, Utah has 23 species. All data approximate and subject to revision.

There are 5 varieties of Cirsium arizonicum in Flora of North America;
Cirsium arizonicum var. rothrockii, (AZ, NM);
Cirsium arizonicum var. arizonicum, (AZ, CA, NM, NV, UT);
Cirsium arizonicum var. chellyense, (AZ, NM)
Cirsium arizonicum var. bipinnatum, (AZ, NM, NV, UT);
Cirsium arizonicum var. tenuisectum, (CA, NV).

Comments: Arizona Thistle characteristics are variable across their relatively wide geographic range with five varieties having been described. This species is used to describe a complicated "complex of species and varieties".

∗The genus Cirsium has received adverse notoriety because of the introduction of two thistles native to Europe and now widespread throughout North America. The Canadian Thistle, Cirsium arvense and and the Bull Thistle, Cirsium vulgare are both listed as noxious primarily by agricultural interests.

Most southwestern native thistles, including Arizona Thistle, are non-aggressive; non-invasive and beneficial as pollinators that have evolved to thrive without becoming weedy. Many native thistles are now threatened with some species at risk of extinction.

In Southwest Desert Flora also see; Graham's Thistle Cirsium grahamii, Mojave Thistle, Cirsium mohavense, New Mexico Thistle, Cirsium neomexicanum and Yellowspine Thistle, Cirsium ochrocentrum.

Importance to Wildlife, Birds and Livestock
Thistles of the genus Cirsium are regularly visited by many wildlife species such as small mammals, hummingbirds and nectar-feeding bats. Also the seeds are attractive to small mammals and finches such as American goldfinch.

Special Value to Native Bees, Butterflies and Insects
Thistles of the genus Cirsium are important as a group as they are frequently visited by pollinators such as Native bees, bumblebees and a very large numbers of insects and butterflies. "Monarch butterflies visit native thistle flowers more than any other wildflowers in some regions during their migration back to Mexico". They are also heavily used as food plants by the larvae of some Lepidoptera (butterfly) species. In addition to food Cirsium also provides nesting material and structure for Native bees and other insects.

To find out more about Butterflies and Moths of North America visit BAMONA.
For excellent information on invertebrate conservation visit The Xerces Society.

The genus Cirsium is derived from the Greek words kirsion "a kind of thistle" in turn from kirsos, "a swollen vein or welt," as thistles are used as a remedy for such issues. The genus Cirsium was published by Philip Miller in 1754.

The species epithet "arizonicum" is a direct reference meaning of or from or otherwise honoring Arizona.


Date Profile Completed: 8/19/2012; updated 02/12/2020
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The Plant List (2013). Version 1.1. Published on the Internet; (accessed 02/06/2020).
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David J. Keil,FNA | Family List | FNA Vol. 19, 20 and 21 | Asteraceae, 43. Cirsium arizonicum; 31: 68. 1911; Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford.
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'Cirsium', Wikipedia, The Free Encyclopedia, 25 January 2020, 15:17 UTC, [accessed 7 February 2020]
James Eckberg, Eric Lee-Mäder, Jennifer Hopwood, Sarah Foltz Jordan, and Brianna Borders; 2017. Native Thistles: A Conservation Practitioner’s Guide
California Native Plant Society, Rare Plant Program. 2020. Inventory of Rare and Endangered Plants of California (online edition, v8-03 0.39). Website [accessed 07 February 2020].
SEINet synonyms, scientific names, geographic locations, general information
Etymology:Michael L. Charters California Plant Names: Latin and Greek Meanings and Derivations; A Dictionary of Botanical and Biographical Etymology - (accessed 02/06/2020)