1 23 ., 



fruit." I found it i;r()\vin.i; near the ranch house this year, but 

 it is still a casual alien. The island lists have been greatly 

 swollen by the inclusion of numerous aliens, so that in statistical 

 treatment the proportion of endemics appears to be much less 

 than it actually is, in relation to the original flora. Many of 

 these aliens can be recognized at once, being of European or 

 other exotic derivation, but there is no ready way to recognize 

 California mainland species which may have been carried over 

 during the past century. To this class would probably belong, 

 for instance Datura meteloides, represented in the Hoffmann 

 herbarium by two specimens, one from Santa Cruz and one from 

 Santa Rosa, and also known from Santa Catalina. Something 

 should be said about the absence of plants which might have 

 been expected to occur. There are no gymnosperms whatever 

 on the southern group of islands. Among the grasses, the Pani- 

 ceae are all absent, and I find no records of Bouteloua, Muhlen- 

 hergia, Sporobolus, etc. Of the genera of grasses included by 

 Munz in his S. California Manual, 26 are present on one or 

 more of the islands, while 39 are absent. Of the Liliaceae, seven 

 are present, eight absent, the latter including Yucca. Myrica, 

 Jiiglans, Alniis, Celtis, Castanopsis, amd Lithocarpus are all 

 absent. Only two genera of orchids are present. In the Ranuncu- 

 laceae, three genera are present, seven absent, the latter includ- 

 ing Paeonia, which from its mode of occurrence on the mainland 

 might have been expected. Of the genera of Compositae (in- 

 cluding Cichoriaceae) recognized by Munz, 61 are present, 66 

 absent. These and similar facts may be taken to indicate that 

 the islands were not united with the mainland very recently. 

 The relationships of the Californian Island flora with that 

 of the Mexican Islands southward is a matter of much interest. 

 Was there once continuous land all the way to Guadalupe 

 Island? The snails would suggest yes, the absence of land mam- 

 mals on Guadalupe, no. But there are eleven of our island 

 endemics which also occur on Guadalupe. These belong to the 

 genera Quercus, Eschscholtzia, Crossosoma, Lotus, Convolvulus , 

 Oenothera, Gilia, Phacelia, Galvesia, Mimidus, and Hazardia. 

 Greene long ago gave lists of the plants he found on Cedros 

 Island and the San Benito Islands, near the coast of Lower 

 California. Of the 91 Cedros species about a fourth are also on 

 the Californian Islands, of the 26 San Benito species, a third. 

 These islands are approximately in Lat. 28°. 



Boulder, Colo. 



