CPC National Collection Plant Profile

Delphinium variegatum ssp. thornei

Photographer:
Dylan Hannon

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CPC National Collection Plant Profile

Delphinium variegatum ssp. thornei


Family: 
Ranunculaceae  
Common Name: 
Thorne's royal larkspur
Author: 
Munz
Growth Habit: 
Forb/herb
CPC Number: 
1389

Distribution
Protection
Conservation
References


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Delphinium variegatum ssp. thorneienlarge
Photographer: Dylan Hannon
Image Owner: Personal

Delphinium variegatum ssp. thorneienlarge
Photographer: Dylan Hannon
Image Owner: Personal


Delphinium variegatum ssp. thornei is Not Sponsored
Primary custodian for this plant in the CPC National Collection of Endangered Plants is: 

 
Delphinium variegatum ssp. thornei


Three varieties of Delphinium variegatum are known. One, D. var. variegatum, is found along the coast and foothills of central and northern California. Another is the Federally Endangered D. var. kinkiense, or San Clemente Island larkspur, which is endemic to (found only on) San Clemente Island, one of the Channel Islands. The subspecies under the care the Center for Plant Conservation is D. var. thornei, or Thorne's larkspur. This subspecies is also endemic to San Clemente, and also considered rare, even more so than the San Clemente Island larkspur. However, this rarest subspecies has no special legal status, although the U.S. Fish and Wildlife Service considers it to be a species of concern.

The San Clemente Island larkspur occurs mainly on the northern end of the island, while Thorne's larkspur occurs mainly on the south. However, the two rare subspecies of San Clemente Island have been the subject of recent study, because there is considerable overlap in their ranges. To date, the only way to consistently distinguish one from the other is by sepal color, with Thorne's larkspur having light blue to bright blue flowers and the endangered San Clemente Island larkspur having white to light blue flowers. Populations that occur in the center of the island have individual plants with white, bright blue, and intermediate flower colors, suggesting that the two subspecies may be hybridizing. (Dodd and Helenurm 2000, 2002)

Distribution & Occurrence

State Range
  California
State Range of  Delphinium variegatum ssp. thornei
Habitat
  Open grassy hills and woods

Distribution
  Delphinium variegatum ssp. thornei (Thorne's royal larkspur) is restricted to southern San Clemente Island. (Dodd and Helenurm 2002)

Number Left
  Roughly 13,000 individuals are known from 13 populations. (USFWS 1996)

Protection

Global Rank:  
G4T1
 
4/29/2002
Guide to Global Ranks
Federal Status:  
SC
 
1/19/1996
Guide to Federal Status
Recovery Plan:  
No
 
1/26/1984

State/Area Protection
  State/Area Rank Status Date  
  California S1.1 5  

Conservation, Ecology & Research

Ecological Relationships
  Unknown.

Threats
  The recent removal of goats from the island has removed the only known threat to this species. (USFWS 1996)

Current Research Summary
  • Recent and ongoing research has been performed on Delphinium variegatum and its three subspecies (var. variegatum, var. kinkiense, var. thornei). Research includes floral variation and genetic diversity. (Dodd and Helenurm 2000, 2002)

Current Management Summary
  The U.S. Navy has jurisdiction over San Clemente Island, has an ongoing program to remove feral goats and pigs in an effort to restore the native vegetation. (CDFG 2002)

Research Management Needs
  • Keep feral goats and pigs out of populations of this species.
• Ensure that invasive species are kept in check on San Clemente Island.

Ex Situ Needs
  • Maintain a genetically representative seed bank.

References

Books (Single Authors)

Munz, P.A.; Keck, D.D. 1959. A California flora. Berkeley, CA: Univ. California Press. 1681p.

Skinner, M.W.; Pavlik, B.M. 1997. Inventory of rare and endangered vascular plants of California: Electronic Inventory Update of 1994, 5th edition. Sacramento: California Native Plant Society.

Smith, J.P.; Berg, K. 1988. California native plant society's inventory of rare and endangered vascular plants of California. Sacramento: California Native Plant Society. 168p.

Books (Sections)

Kartesz, J.T. 1999. A synonymized checklist of the vascular flora of the U.S., Canada, and Greenland. In: Kartesz, J.T.; Meacham, C.A., editors. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden. Chapel Hill, NC.

Electronic Sources

CDFG. (2002). California's Plants and Animals, Threatened and Endangered Plants. List and Species Accounts. California Department of Fish and Game, Habitat Conservation Planning Branch. http://www.dfg.ca.gov/hcpb/species/t_e_spp/teplant/teplanta.shtml. Accessed: 2002.

Journal Articles

Beattie, A.J. 1983. Distribution of ant-dispersed plants. Sonderbande des Naturwissenchaftlichen Vereins in Hamburg. 7: 249-270.

Dodd, S.D.; Helenurm, K. 2000. Floral variation in Delphinium variegatum (Ranunculaceae). Madroño. 47: 116-126.

Dodd, S.D.; Helenurm, K. 2002. Genetic diversity in Delphinium variegatum (Ranunculaceae): a comparison of two insular endemic subspecies and their widespread mainland relative. American Journal of Botany. 89: 613-622.

USFWS. 1996. Notice of Reclassification of 96 Candidate Taxa. Federal Register. 61, 40: 7457-7463.

Reports

USFWS. 1984. Recovery plan for the endangered and threatened species of the California Channel Islands. Portland, Oregon: U.S. Fish and Wildlife Service.


  This profile was updated on 3/4/2010
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