1921] 
PAYSON—MONOGRAPH OF THE GENUS LESQUERELLA 123 
rosettes, the suborbicular basal leaves, the short stems, and the 
pubescent, globose, or obcompressed pods. Our interest cen- 
ters chiefly in L. utahensis because it is believed that from it or 
from some similar form has been developed the genus Physaria. 
Indeed the pods of some individuals of L. utahensis suggest that 
genus almost as much as they do Lesquerella. 
15. The occidentalis group contains the remaining species of 
the genus, L. diversifolia, L. occidentalis, L. Cusickia, and L. 
Douglasii. The first three of these might be regarded as a 
single species in a more conservative treatment. They are 
peculiar because of the compressed margins of the pods. The 
first named is presumably the most primitive, though not neces- 
sarily so. Certainly L. Cusickii has been derived from one or 
the other. L. Douglasii does not exhibit the compression of the 
capsules and has possibly, though not probably, had a separate 
origin. It, as well as the other three, seems to have been de- 
rived from the utahensis group. 
GEOGRAPHICAL DISTRIBUTION 
It is believed that in geographical distribution is to be found 
a most valuable check to any theories of phylogeny derived from 
purely morphological studies. Furthermore, distribution is an 
important aid in deciding the relative value of variations for 
taxonomic purposes. For instance, it is often difficult to decide 
if a given form merits taxonomic recognition. In the present 
work the attitude has been taken that if such a form occurs in 
company with the normal form throughout its area of distribu- 
tion it is to be regarded as a variation produced by environment, 
or at least not yet sufficiently distinct to be given a systematic 
position. If, on the other hand, the variant occurs in a region 
adjacent to that occupied by the parent species it does certainly 
deserve treatment by the taxonomist. This attitude is in a 
measure arbitrary and exceptions have been made when the 
variation seemed definite enough to warrant it. Besides these 
reasons for interest in geographical distribution there are certain 
phases of the subject that deserve consideration on their own ac- 
count quite apart from any taxonomic or phylogenetic aspect. 
The preference of many of the species for calcareous soil has been 
noted, and as a matter of general interest this peculiarity has ` 
