TORREYA 



\()1. .^7 November-Uecember, 1937 No. 6 



The botany of the California Islands 



T. D. A. COCKERELL 



There are eight islands off the coast of Southern California. 

 The northern group, visible from Santa Barbara, are Anacapa, 

 Santa Cruz, Santa Rosa, and San Miguel, enumerating them 

 from east to west. The southern group, much more widely 

 scattered, consists of Santa CataUna, San Clemente. vSanta 

 Barbara and San Nicolas. It is confusing to find the northern 

 islands often referred to as the Santa Barbara islands, whereas 

 Santa Barbara Island is the smallest of the southern group. 

 These islands, believed to have been separated from the main- 

 land in Pleistocene times, are of extraordinary interest because 

 they have upon them so many endemic animals and plants. 

 The endemic animals include fifteen mammals, fifteen birds, two 

 lizards, two salamanders, sixteen land molluscs, and an undeter- 

 mined number of insects. The plants include over eighty species 

 and races. 



Although the islands were discovered by the expedition led 

 by Captain Juan Rodriguez Cabrillo in 1542, knowledge of 

 their plants came very slowly. Nearly 90 years ago Nuttall de- 

 scribed a few from the collections of Dr. \Vm. Gambel, the 

 ornithologist, who visisted California at the beginning of the 

 forties. These included the remarkable endemic shrub, Crosso- 

 soma californicum Nuttall, the only genus of the family Cros- 

 sosomataceae. A second species, C. Bigelovii Watson, has since 

 been found on the mainland, in the desert area of the south- 

 west. After a very long interval, the botany of San Clemente 

 was partly made known through a visit in 1885 of J. C. Nevin 

 and \A'. S. Lyon (Madrono, Vol. 2, 1931, p. 25), who discovered 

 some very interesting endemics. It was Lyon who sent to Asa 

 Gray the endemic and very distinct genus of trees, Lyonotham- 

 nus, found by him on Catalina Island. Not long after, E. L. 

 Greene visited Santa Cruz and San Miguel: on San Miguel he 

 was in time (1886) to see growing the tree-mallow, Lavatera, 

 which has now entirely disappeared from the island. In more 



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