Cirsium vulgare, the spear thistle, bull thistle, or common thistle, is a species of the Asteraceae genus Cirsium, native throughout most of Europe, Western Asia, and northwestern Africa. It is also naturalised in North America, Africa, and Australia and is an invasive weed in some areas. It is the national flower of Scotland.
Cirsium fontinale, the fountain thistle, is a flowering perennial herb in the family Asteraceae. It is endemic to California. The genus Cirsium is commonly known as the "thistle" genus, Cirsium being the Greek word for 'thistle.'
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 brevistylum is a species of thistle known by the common names Indian thistle and clustered thistle. It is native to western North America having been found in southwestern British Columbia, Washington, Oregon, Idaho, Montana, and California.
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 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 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 ownbeyi, or Ownbey's thistle, is a rare North American species of flowering plant in the family Asteraceaey. It is endemic to the United States, where it has a narrow distribution in northeast Utah, southwest Wyoming, and northwest Colorado. There are around 30 known populations with a total of approximately 25,000 individuals.
Cirsium perplexans is a species of flowering plant in the family Asteraceae known by the common names Rocky Mountain thistle and Adobe Hills thistle. It is endemic to Colorado in the United States, where it occurs in the Colorado and Gunnison River Valleys in the Rocky Mountains.
