302 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 13 



Quercus tomentella Scrophularia calif ornica 



Eriogonum gigantum var. catalina 



Cercocarpus betuloides Castilleja hololeuca 



var. Traskiae Phacelia ftoribunda 



Astragalus Nevinii Aplopappus canus 



Astragalus Traskiae Eriophyllum Nevinii 



Solanu?n Wallacei 

 A study of the endemics of the Channel Islands leads to a clear 

 conception of the essential floristic unity of the island group. The large 

 majority of the endemics are to be found on three or more of the islands. 

 Many of those limited to one island are apparently, for the most part, 

 recent initial endemics, many possessing only varietal status. Many of 

 the endemics seem closely related to and apparently derived from Cali- 

 fornia species. Others, however, do not appear to be closely related 

 to any existing California species. These may be considered to be relicts 

 from a Pleistocene Mexican invasion which only locally survived the 

 colder or wetter climates of the glacial stages. Some of these may even 

 be relicts from the hypothetical ancient land of Catalinia. There are 

 also a number of plants endemic to the area covered by the maritime 

 climate, many of which are more numerous and more vigorous on the 

 islands than on the mainland coast. Since both prevailing winds and ocean 

 currents are such as to make migration from the islands to the mainland 

 more probable than the reverse migration, such plants may probably 

 have originated on the island and will be listed with the insular en- 

 demics. Table 7 presents the distribution of the insular endemics, in- 

 cluding plants found otherwise only on Guadalupe Island or the im- 

 mediately adjacent mainland coast. 



Table 7 shows eighty plants endemic to the area of the Channel 

 Islands, with twenty-four more occurring otherwise on Guadalupe 

 Island and seventeen others growing otherwise only in mainland coastal 

 areas which possess a maritime climate. Of the eighty strictly Channel 

 Island endemics fifty are to be found on two or more of the islands, 

 twenty-six are common to islands of both the northern and southern 

 groups, eighteen are common to one or more islands of the northern 

 group and nine are common to one or more islands of the southern 

 group. This would tend to support the hypothesis that all of the islands 

 were at one time part of a common land mass, but that the northern 

 islands have, at another time, formed a separate geological province. 

 The greater separation of the islands of the southern group is shown 

 not only by the smaller number of endemics common to two or more 

 of these islands, but there are twenty-two endemics limited to single 



