1 82 W. S. Cooper 



Species of Stable Dunes 



Of the eighteen species in this group, representing sixteen genera, 

 all but two are endemic. Cardionema ramosissima occurs also 

 in western South America; Artemisia campestris var. pycnoce- 

 phala is excluded from the list of endemics solely because of the 

 wide concept of the species here adopted. The group is not so 

 stricdy coastal as are the strand species. Nemacaulis dentidata, 

 Mucronea californica, and Cardionema ramosissima occur also 

 in the lowlands of southern California, Corethrogyne filagini- 

 folia is found there and in the south Coast Ranges and Sierras, 

 and Croton californicus in the Great Basin and eastward to Texas. 



Six of the genera it^xts^Tittd—Eriogonum, Eriophyllum, 

 Nemacaulis, Mucronea, Monardella, Corethrogyne— 2.1^ con- 

 fined to western North America. If a narrower view of ge- 

 neric limits were adopted, Hor\elia (Potentilla) and Ericameria 

 (Haplopappus) would be added to this group. Lupinus and Cas- 

 tilleja, though not confined to western Nordi America, attain 

 their greatest development there. Atriplex, Croton, and Arte- 

 misia are widespread, but all are abundandy represented in west- 

 ern America. Chorizanthe and Cardionema occur also in South 

 America. 



It is quite evident that almost all members of the group are 

 of local origin. Differentiation within certain important genera 

 of the arid interior has given rise, along the coast, to forms more 

 or less stricdy confined to the ocean shore. Two genera, Nema- 

 caulis and Corethrogyne, are monotypic; in the latter, however, 

 there has been differentiation into a multitude of minor forms 

 more or less distinct. Both are so closely connected with related 

 genera that we are justified in assuming local origin. All but one 

 species of the group must therefore be placed with the list of nine 



