56 
The effects of humidity, other things being the same are shown 
in the Columbia Basin, As we approach the Columbia Basin there 
is a marked increase in spring and summer humidity though there is 
less summer rainfall. The winter snows are deeper and the snow 
cover is permanent through most of the region in the winter months, 
which is a great protection to the vegetation. There is less alkali. 
The species of Astragalus become more slender and with more woody 
roots. The Revénti-Arrecti and Collini prevail; there are some 
Atrati, some Homalobi, and Podo-sclerocarpi, and a number of Argo- 
phylli. No species have phyllodia-like leaves, few have broad leaflets 
and most of these are folded and pubescent. The speties are almost 
exclusively perennial. It is a region of abundant spring flora, par- 
ticularly grasses, 
The northern Plains along the trough of slight rainfall caused by 
the Rockies has a humidity a little higher than the Coumbia Basin 
and is wind swept throughout the year, and with a low temperature 
There is a permanent snow cover except where elevations catch the 
wind. There is a little alkali. These conditions have produced the 
densely matted Homalobi and Triphylli with their scapose pedun- 
cles hidden among the leaves and their narrow, thick and silvery 
leaves and large and densely imbricated stipules. -It is only in the 
bottoms where the snow cover is not disturbed that the slender and 
variably erect species are found such as the Bisulcati and pectina- 
tus in alkaline places, the slender Homalobi, Debiles and Hypoglot- 
tides. get cgo á 
The interior valley region of California simulates the Arizona- 
Death Valley region in its Tropical climate and extensive annual 
flora, and some species are' common to both regions, but the higher 
humidity and winter rains have greatly increased the species and indi- 
viduals. Here abound the Didymocarpi, and Leptocarpi. The 
salt marshes have the annual A. Hornii and the remarkable perennial 
A. pychnostachyus. . It is a notic&able fact that nearly all Californian 
Astragali have short pubescencé closely appressed.’ da E 
The Coast region of California has a remarkable development 
of the Inflati, along with a few  Hamosi, in addition to the 
annuals of the interior region. Its chief characteristics are high 
temperature, high humidity (due to fogs) and no rainfall except in 
winter. We therefore find no species with phyllodia, or stems with 
leaf functions, There is a large development of: leaf surface with 
folded leaflets and slender stems. The Argophylli are mostly absent, 
and the Homalobi scarce, as are most other groups. © ° > | 
In the Sierra region the Astragali are scarce in the forested- 
area. At the north A. aecidens is found among the bushes, and, 
Californicus and inversus among the yellow pines. Higher up we. 
find A. Cohgdoni, Bolanderi and Hookerianus, mostly: farther: south, . 
but the soil is a very granular granite and not adapted to any vege- 
tation, and so the general flora is meager. "ick WP 
` The Argophylli, plants of the lower mountain slopes with no per 
manent winter snow cover, with plenty of spring humidity due to. 
rains or melting snows show a curious distribution. Inthe*Columbia — 
region they develop a loose and cottony pubesence, narrow flowers, . 
and lax stem system. A. inflexus even attempts to become erect. 
The Argophylli are normally c&spitose and prostrate’ species. This 
condition of the Columbia species is manifestly due to higher humidity 
and light soil. As the group extends south along the Sierras in the 
impoverished soil the same species become densely matted and ‘often 
only en inches across, with very short stems, small leaves ánd very 
small flowers and pods. At the foot of the monutains and' out on 
we have the magnificent A. coocineus, and funereus far surpassing’ 
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