Cirsium neomexicanum is a North American species of thistle known by the common names New Mexico thistle, powderpuff thistle, lavender thistle, foss thistle and desert thistle.
Cirsium occidentale, with the common name cobweb thistle or cobwebby thistle, is a North American species of thistle in the family Asteraceae.
Cirsium andersonii is a North American species of thistle known by the common names Anderson's thistle and rose thistle. It is native to California, Oregon, and Nevada, where it grows in the woodlands and forest openings of the local high mountain ranges, including the Sierra Nevada and the southern Cascade Range. It has also been reported from Idaho.
Cirsium andrewsii is an uncommon species of thistle known by the common name Franciscan thistle. It is endemic to California, where it is known from the coastline of the San Francisco Bay Area from Marin to San Mateo Counties. There are also reports of isolated populations in the Klamath Mountains and in the Sierra Nevada.
Cirsium ciliolatum is a species of thistle known by the common name Ashland thistle. It is endemic to the Klamath Mountains, where it is known from only a few occurrences in Jackson and Josephine Counties in Oregon, as well as neighboring Humboldt and Siskiyou Counties in California. It is related to Cirsium undulatum and may be more accurately described as a variety of that species.
Cirsium crassicaule is a species of thistle known by the common name slough thistle. It is endemic to the San Joaquin Valley of California, where it is known primarily from freshwater wetlands. It has been found in only a few locations in Kern, Kings, and San Joaquin Counties.
Cirsium cymosum is a North American species of thistle known by the common name peregrine thistle. It is native to the western United States, where it has been found in California, Oregon, Nevada, Utah, Idaho, Wyoming, and Montana.
Cirsium douglasii is a species of thistle known by the common names Douglas' thistle and California swamp thistle.
Cirsium hydrophilum is a species of thistle which is endemic to California, where it is found only in the San Francisco Bay Area and the Sacramento-San Joaquin River Delta. This native thistle grows in wet boggy habitats.
Cirsium loncholepis is a rare species of thistle known by the common name La Graciosa thistle. It is endemic to California, where it is known from about 15 remaining occurrences in wetlands where southwestern San Luis Obispo County borders northwestern Santa Barbara County. It grows in coastal scrub and sand dunes, marshes, and moist grasslands in the watersheds of local rivers, including the Santa Maria River. It is a federally listed endangered species.
Cirsium mohavense is a species of thistle known by the common names virgin thistle and Mojave thistle. It is native to the southwestern United States, where it grows in moist areas in otherwise dry habitat, such as desert springs. It is most common in the Mojave Desert, found also in the southern Great Basin and other nearby regions of California, Nevada, western Arizona, and southwestern Utah.
Cirsium ochrocentrum is a species of thistle known by the common name yellowspine thistle. It is native to the Great Plains of the Central United States and to the desert regions of the western United States and northern Mexico. Its range extends from eastern Oregon east to the Black Hills of South Dakota, south as far as the Mexican State of Durango.
Cirsium remotifolium is a species of thistle known by the common name fewleaf thistle. It is native to the western United States, including the Pacific Coast and possibly as far east as the Rocky Mountains, depending on which populations are treated as part of the species. It is sometimes part of the serpentine soils flora. This native thistle is a perennial herb growing up to about 1.5 meters tall. The leaves are borne on spiny petioles and are toothed or lobed, the lowest leaves at the base of the stem reaching 50 centimeters in length. The inflorescence is made up of clustered flower heads which are lined with spiny phyllaries. The head is filled with white or purple flowers up to 2.5 centimeters long. The fruit is an achene a few millimeters long topped with a pappus up to about 2 centimeters in length.
Cirsium rhothophilum is a rare North American species of thistle known by the common name surf thistle. It is endemic to California, where it is known only from the coastline around the border between San Luis Obispo and Santa Barbara Counties. It grows in sand dunes and coastal scrub near the beach.
Cirsium scariosum is a species of thistle known by the common names meadow thistle, elk thistle and dwarf thistle. It is native to much of western North America from Alberta and British Columbia, south to Baja California. There are also isolated populations on the Canadian Atlantic Coast, on the Mingan Archipelago in Québec, where it is called the Mingan thistle.
Cirsium undulatum is a species of thistle known by the common names wavyleaf thistle and gray thistle. It is native to much of central and western North America from British Columbia east to Manitoba and south as far as the State of Durango in Mexico. It has also been found outside of its native range as an introduced species.
Cirsium vinaceum is a rare species of thistle known by the common name Sacramento Mountains thistle. It is endemic to Otero County, New Mexico, in the United States, where it is known only from the Sacramento Mountains. The plant can be found in six canyon systems in a southern section of this mountain range spanning about 32 kilometers. It is rare because it is limited to a specific type of mountain wetland which is both naturally uncommon and threatened by a number of forces. The plant was federally listed as threatened in 1987.
Cirsium barnebyi, or Barneby's thistle, is a North American plant species native to the Rocky Mountains of the western United States. It grows in juniper woodlands, sagebrush scrub, etc., at elevations of 1,600–2,600 m (5,200–8,500 ft). It is reported from 6 counties in 3 states: Rio Blanco and Garfield Counties, Colorado; Uintah, Carbon and Duchesne Counties, Utah; and Carbon County, Wyoming.
Cirsium wrightii, or Wright's marsh thistle, is an endangered species of North American plants in the family Asteraceae. It is a monocarpic perennial sometimes reaching as much as 300 cm in height.
Cirsium altissimum is a North American species of plants in the tribe Cardueae within the family Asteraceae. Common names are tall thistle or roadside thistle. The species is native to the eastern and Central United States.
