The following Participating Institutions are custodians for this species in the CPC National Collection:
Santa Barbara Botanic Garden
The conservation of Cirsium loncholepis is fully sponsored.
Dieter Wilken contributed to this Plant Profile.
La Graciosa thistle is found in coastal wetlands of southwestern San Luis Obispo County and northwestern Santa Barbara County, California. It is named for La Graciosa, a place name provided by Portol in 1769, and near where the original collection was made near what is now the community of Orcutt. Based on historic records, its geographic range remains the same, but fewer than 15 extant populations are believed extant. Many of the known populations are clustered in a few remaining watersheds, including the Santa Maria River and San Antonio Creek in northwestern Santa Barbara County. The average life span is unknown, but some populations are often composed mostly of vegetative plants in different size classes (Teed 2003). Flowers are typically white or tinged with purple and are borne in densely clustered heads (Ferris 1960; Hoover 1970; Keil 2006; Smith 1998). Plants may flower from April to late summer, especially near the coast. It is often mistaken with several other related thistles with preferences for wetland habitats.
Distribution & Occurrence
La Graciosa thistle occurs naturally in open sites in wet swales of coastal back dunes, the edges of marshes, and broad river flood plains. It is often associated with such riparian and flood plain species as rushes (Juncus), sedges (Carex), coyote brush (Baccharis pilularis), and arroyo willow (Salix lasiolepis) (Anonymous, 2008a; Hendrickson, 1990).
|Among approximately 20 historic occurrences in California, 15 are believed to be extant. With a single exception, only 2-30 plants have been reported at most occurrences, but estimates vary widely based on whether both vegetative and flowering individuals were counted. The notable exception is a population near the mouth of the Santa Maria River in the Guadalupe Dunes Wildlife Refuge, where at least 500 individual plants were observed in 2001 (Anonymous, 2008b).|
Conservation, Ecology & Research
Competition from alien invasives.
Trampling by livestock.
Expansion of sand dunes, resulting from excessive ORV use.
Potential seed predation by thistle head weevil (Rhinocyl
A better understanding of life history traits and appropriate habitat for sustainable populations.
Development of a propagation protocol.
Anonymous. 2008a. Vascular plants, bryophytes, and lichens list. Sacramento. California Department of Fish and Game, Natural Diversity Database, Sacramento. Quarterly Publication. 70.
Anonymous. 2008b. California Natural Diversity Data Base. RareFind.Version 3.1.1. Sacramento. California Department of Fish and Game.
Ferris, R.S. 1960. Illustrated flora of the Pacific states. Volume IV. Stanford University Press, California. 732p.
Hoover, R.F. 1970. The vascular plants of San Luis Obispo County, California. Berkeley. University of California Press. 350p.
Smith, C.F. 1998. A flora of the Santa Barbara region, California. Santa Barbara, California. .Santa Barbara Botanic Garden and Capra Press. 391p.