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San Clemente Island

With an area of 56 square miles, San Clemente Island is the second-largest of the Southern Channel Islands and is the fourth-largest island in the entire chain. It is situated 49 miles off the southern California coastline. Santa Catalina Island, San Clemente’s closest island neighbor, is located 21 miles to the north.
The flora of San Clemente Island includes about 300 native taxa and about 135 non-native taxa. The natural distribution of at least 47 of the island’s native taxa are restricted to two or more of the California Islands; 15 plant taxa have been found only on San Clemente Island.

The 15 plant taxa which have been found only on San Clemente Island are:

  • Acmispon argophyllus var. adsurgens (San Clemente Island silver lotus)
  • Acmispon dendroideus var. traskiae (San Clemente Island deerweed)
  • Astragalus nevinii (San Clemente Island milkvetch)
  • Brodiaea kinkiensis (San Clemente Island brodiaea)
  • Camissoniopsis guadalupensis subsp. clementina (San Clemente Island evening-primrose)
  • Castilleja grisea (San Clemente Island paintbrush)
  • Delphinium variegatum subsp. kinkiense (San Clemente Island larkspur)
  • Delphinium variegatum subsp. thornei (Thorne’s royal larkspur)
  • Dudleya virens subsp. virens (San Clemente Island live-forever)
  • Eriogonum giganteum var. formosum (San Clemente Island buckwheat)
  • Galium catalinense subsp. acrispum (San Clemente Island bedstraw)
  • Lithophragma maximum (San Clemente Island woodland star)
  • Malacothamnus clementinus (San Clemente Island bush-mallow)
  • Munzothamnus blairii (Blair’s munzothamnus)
  • Triteleia clementina (San Clemente Island triteleia)

Garden Research on San Clemente Island

image of Castilleja grisea, San Clemente Island, photo by Tricia Wardlawimage of Malacothamnus clementinus on San Clemente Island, photo by Tricia Wardlaw

SBBG researchers have established long-term population monitoring protocols for San Clemente Island bush mallow (Malacothamnus clementinus) and San Clemente Island indian paintbrush (Castilleja grisea) as part of an effort to determine conservation status of these federally listed species.

At least one insular endemic that previously occurred on San Clemente Island is now thought to be extinct:

  • Lycium brevipes var. hassei (Santa Catalina Island box-thorn) was previously known from Santa Catalina and San Clemente islands but has not been seen on either island since the early 1900s.