NO. 2 gentry: land plants 17 



when genetic values are obtained. Hence, pending the genetic stages of 

 taxonomic inquiry into the plants of the regions considered, the nomen- 

 clature has been kept simple. 



Synonomy is given when required in proposing new names and also 

 in a few cases of special significance. 



CHANNEL ISLANDS 



Introduction 



The southern California coast from Point Arguello southeastward 

 describes a long shallow irregular curve. The outer margin of the con- 

 tinental shelf, trending more nearly southward, accordingly broadens. 

 Its submarine surface is irregular with submarine valleys and ridges; 

 the topography suggesting land surface rather than sea bottom. The 

 greatest heights of the shelf rise above the sea and form the Channel 

 Islands, bearing the appellations cast upon them by the early Spaniards, 

 San Miguel, Santa Rosa, Santa Cruz, Anacapa, Santa Catalina, Santa 

 Barbara, San Nicolas, and San Clemente. They comprise a residual area 

 of considerable antiquity, which, according to Reed (1933) and other 

 geologists, dates from the Cretaceous. The ratio of sea to land area over 

 the shelf has varied greatly, but during much of the Tertiary this shelf 

 segment actually formed a large land body, known as Catalinia. In the 

 early Miocene and again in the Pleistocene, if not also at other times, 

 Catalinia appears to have been bridged to the continent. 



Structurally the islands are separated into two groups. The northern 

 consists of San Miguel, Santa Rosa, Santa Cruz, and Anacapa, repre- 

 senting disjunct segments of the Santa Monica Mountains, which ap- 

 pear to have been more variably emerged and submerged in the sea than 

 has the southern group. The southern group, consisting of Santa Bar- 

 bara, Santa Catalina, San Nicolas, and San Clemente, have been part 

 of a more consistent land area and are structurally tied to the San Pedro 

 peninsula. The present islandic configuration is the result of geologically 

 recent submergence of all but the higher elevations. The biota of such 

 a land area can be expected to difler considerably from that of the near 

 mainland and actually the evolution of the plants and animals is to be 

 correlated with that of the land. Behind the present configuration of 

 flora and fauna the elusive steps of evolution can be discerned. 



The climate of the Channel Islands is Mediterranean in type, semi- 

 arid, and, of course, maritime. The average annual rainfall is around 

 12 inches, about 90% of which is precipitated in winter (November 



