Flowering Season: July or August to September or October, blooms following summer monsoons.
Elevation: 4,500 to 8,500 feet (1,372-2,591 m)
Habitat Preferences: Various high elevation habitats including pine forest openings, evergreen oak communities, closed grassy basins, meadows and damp soil.
Recorded Range: A rare thistle in the United States with a very limited distribution in the mountains of southeastern Arizona and southwestern New Mexico. Graham’s Thistle is also recorded in northern Mexico (Chihuahua, Durango, Sonora).
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: No data available.
Threatened/Endangered Information: No data available
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.
Comments: There is little botanical information for Graham’s Thistle which like many native thistles have limited geographic distribution and are not aggressive or noxious weed as notorious thistles. It appears to be more specialized in its habitat requirements as suggested by its extremely limited geographic range. Superficially similar in appearance to Wheeler’s Thistle, Cirsium wheeleri. According to The Flora of North America "It forms hybrid swarms with C. parryi and C. scariosum var. coloradense in the White Mountains of Arizona".
∗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 Graham's 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.
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 vertebrate 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 grahamii is named in honor of Virginia born James Duncan Graham (1799-1865), a West Point graduate and army officer. Mr. Graham is one of the founders of the army's topographical section and well known for his map making skills.