1903] FLORA OF SOUTHERN CALIFORNIA 219 
of them. I have separated the genera of each group into two 
sections; a northeastern section for those whose extensions are 
into Nevada, Utah, and the Great Basin life-area; and a south- 
eastern section to include those whose extensions of range are 
into Arizona, and towards or into northern Mexico. There 
remains a group in the third column whose affinities cannot be 
stated definitely, mostly because represented by more than one 
species which have diverse ranges. Genera which are repre- 
sented by species which also extend into the peninsula of Lower 
California are distinguished by an asterisk. Washingtonia has 
its only extension in that region. 
It is to be noted that Astephanus, the single northeastern 
genus peculiar to the Colorado subarea, is known from a single 
collection. All the others are southeastern, and all but ten 
extend into Lower California. On the other hand Canotia and 
Fallugia, two of the southeastern plants of the Mojave subarea, 
are found only in the Providence Mountains, which may belong 
to the Colorado subarea. Only four of the peculiar Mojavan 
plants have been reported from Lower California. 
Like geographical affinities are exhibited by the different 
Species of certain genera which are differently represented in 
each subarea. A longer list than the following might be com- 
piled, but these examples must suffice. 
DISTRIBUTION OF CERTAIN DESERT SPECIES. 
Colorado Subarea 
Mojave Subarea 
ave *deserti 
Aster Orcuttii 
Cassia *Covesii 
Coldenia canescens 
eri 
Dalea *Emoryi 
arryi 
— Schott 
*spinosa 
Gila *bella 
*Sch 
acelia micrantha 
Psathyrotes Weamoxioline 
Agave utahensis 
Aster peony 
Cassia 
Coldenia "Nuttallii 
Dalea Fremonti 
mara < 
olydenia 
Gilia dichotoma 
Psathyrotes annua 
