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Plant Profile

Ownbey's Thistle (Cirsium ownbeyi)

Full view of flowering plant in native habitat. Note the finely divided lobes of the leaves. Photo Credit: Carol Dawson

Global Rank: G3 - Vulnerable
Legal Status: N/A
Family: Asteraceae
State: CO, UT, WY
Nature Serve ID: 149014
Lifeform: Forb/herb
Date Inducted in National Collection: 02/25/1988

Description:

Ownbey's thistle is the rarest native thistle in Colorado. First discovered in the state in 1987, it is found in the dry canyons and cliff walls of northwestern Colorado and northeastern Utah. Current research is attempting to determine the effect of an introduced biocontrol agent (Rhinocyllus conicus) on the seed production of the plant. This thistle is incredibly spiny and has white to rose colored flowers. The spines may help to protect the plant from water loss or grazing. The plant is found on lands managed by the Bureau of Land Management and National Park Service (Dinosaur National Monument). (Von Bargen 1997)

Where is Ownbey's Thistle (Cirsium ownbeyi) located in the wild?

Habitat:

Sparsely vegetated juniper, sagebrush, and riparian communities. Gravelly alluvium, talus, or sandy slopes; usually on sandstone and occasionally on limestone of the Weber and Morgan formations. Often associated with alcove seeps and abandoned stream channels. Elev. 5500-6200 ft. (Spackman 1997)

Distribution:

Endemic to the east flank of the Uinta Mountains in Daggett and northern Uintah counties, Utah; Sweetwater Co. in SW Wyoming, and Moffat County in NW Colorado. (Atwood et al. 1991)

States & Provinces:

Ownbey's Thistle can be found in Colorado, Utah, Wyoming

Which CPC Partners conserve Ownbey's Thistle (Cirsium ownbeyi)?

Denver Botanic Gardens

Not Sponsored

Conservation Actions

Assigned 06/09/17

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

09/07/2020

The Denver Botanic Gardens has been sampling populations of C. ownbeyi at Cross Mountain Canyon, Colorado, to determine the effect of the introduced biocontrol on seed production of this native thistle.

Nature Serve Biotics

05/02/2017

Cirsium ownbeyi occurs across a very restricted range as a regional endemic to Colorado, Utah, and Wyoming. It is known from nearly 30 extant occurrences, with over 25,000 individuals, many on habitat that is somewhat self-protected. However, increased visitor use at the Dinosaur National Monument, where it occurs, poses a threat. The plant does seem to be adapted to natural surface disturbances.

Thomas Grant

01/01/2010

Visitor traffic at Dinosaur National Monument and seed predation by Rhinocyllus conicus, a seed-eating weevil. This insect has been introduced across the intermountain western United States to help control Musk Thistle, a non-native noxious weed (Atwood

Thomas Grant

01/01/2010

Remaining individuals are unknown.

Thomas Grant

01/01/2010

Thomas Grant

01/01/2010

Management strategies may have to account for the influence of the biocontrol agent.

Thomas Grant

01/01/2010

Insect exclusion techniques need to be tested, especially if the biocontrol is shown to have a negative effect on seed production.

Thomas Grant

01/01/2010

Seed collection, banking, germination, and growth protocols need to be established.