43 
the shade of oak brush, the former also in abandoned fields, A 
simplieifolius is rare on bare mesas at the north. A. Geyeri and 
lentiginosis are scattered over the sandy plains. A. subcinereus' 
replaces pictus at the south, A. megacarpus is rare along the high 
draws and in the edge of the oak zone in very barren clay. A, am- 
phioxys is frequent over the sandy plains, as is A. pygmeus at the 
north. A. cymboides and Musiniensis frequent the gravelly mesas. 
A. Utahensis and Purshii are rare higher up, in the gravel. A. 
scopulorum occurs in the oak brush. A. debilis grows in high mea- 
does as does A. argophyllus. A. lonchocarpus grows on alkaline and 
sandy flats and slopes. The unvsnal spruce zone species occur on 
the high peaks bnt they are not distinctive. The effect of barriers 
is such that the whole flora is very peculiar, Very few species ex- 
tend over to the Rio Grande drainage beyond the San Juan. A. as- 
clepiadoides, Coltoni, lonchocarpus, Megacarpus and Hayden- 
lanus pass over the Wasatch Plateau into the edge of the Great Basin, 
Only A. Geyeri and lentiginosus are of general distribution, caused 
evidently by winds from up the Colorado, A few species come in 
from the north around the Uintas such ag confertiflorus, pygmzus 
and simplicifolius, but only the latter is a real immigrant as the 
others have migrated out rather than in. A. calycosus has come in 
from the Great Basin. A. tenellus has come down from the high 
peaks. A. Utahensis and Purshii are evidently immigrants, as is A. 
argophyllus. It is interesting to note the effects of certain ecolo- 
gical factors on the development of certain species . Astragalus de- 
speratus is normally a densely tufted plant from a woody crown and 
about six inches. high, with long leaves and many leaflets and long 
peduncles having many densely racemose flowers about 1 cm. long. 
This is when it grows in wide crevices in the sandstone rocks. When 
it grows in loose sand areas on the rocks and near them it is 
much the same but mostly prostrate in mats. When growing 
in tight and narrow crevices which is the common state on bare rocky 
knolls or eroded and gently sloping rocks it is reduced to a rosette . 
often only % inch wide with short leaves and few leaflets and short 
peduncles with only a flower or two and ä single mottled pod. The 
flowers are then hardly larger than A. montanus and broad, and the 
general appearance is that of the tegetarius variety, the whole closely 
resembling A. humillimus but with few stems and not densely matted 
-in broad mats. 
On the Tropical part of the Navajo Basin annual Inflati come in, on 
. the sandy stretches. 
This Basin belongs in the second grand division. * 3 
The Green River Basin of Wyoming is a little area with th 
same badland soil as the upper Navajo Basin, but is far colder, Its 
flora is peculiar, with several distinct forms, but in Astragali is 
not worth mentioning except one form, A. Grayi, a derivative from A. 
` pectinatus. . Its climate is a mixture of the Atlantic and Pacific hu- 
midity and rainfall. 
The northern Plains region has a meager Astragaline flora, be- 
longs to the first grand division and is caused chiefly by wind 
movement and the low rainfall and temperature of the trough along 
the east base of the Rockies. : ` 
. The Columbia Basin is an interesting group of the Pacific grand 
division of floras. Its factors are mountain isolation, snow cover 
except in the center in winter, rather high spring humidity continuing 
more or less through the summer, and almost total absence of sum- 
mer rains. This insures a copious spring flora, and a conspicuous 
grass cover but no sod. There is a limited alkaline area in narrow 
stretches where few peculiar Podo-sclerocarpi flourish. The grass 
region supports the Collini and Reventi-Arrecti, and some Argo- 
