17 
A. desperatus belongs in the Argophylli. A. Drummondii, racemosus 
and scopulorum belong in the Galegiformes. A. obcordatus and va- 
riegatus (sparsiflorus) belong in the Sparsiflori. A. humistratus be- 
longs in the Homalobi. A. distortus belongs in the Hamosi probably. 
He creates Xylophacos to include Gray’s Argophylli. 
PRESENT REVISION. 
The writer began his work on the revision of the genus in 1895, 
a year after the appearance of Sheldon’s abortive “Preliminary List,” 
in the belief that no closet botanist could ever revise the genus pro- 
perly, and with the intention to work out the genetic relationship 
of all the North American species in the field. I had already spent 
sixteen years in the field on the genus along with other flowering 
plants, but with no intention to revise it. 
My first work was an examination of all the types in this 
country and photographing them, which was the first work of that 
kind in this country. Then some years were spent in a fruitless 
attempt to follow Gray and Watson. «When I had the genus about half 
done the scheme utterly collapsed. The mass of genetic and ecologic- 
nl information accumulated in the field and the great amount of 
material seen which embraced all to be found in all the leading her- 
baria in the country, and the study of nearly every species in the field 
compelled me to attempt à new classification. For a time the arch- 
ing of the ventral suture offered much encouragement, but this also 
hroke down with a very few species. I then took up the genus 
from an ecological and genetic view-point, making much of geogra- 
phical proximity, and this led me out where I believe the genetic 
relationship of all the species is no longer guess-work but an estab- 
lished fact. These studies showed that the intrusion of the sutures 
though valuable on the whole must not be relied on, nor the thick- 
ness of the walls of the pods, nor the inflation. The differentiation 
of the genus has gone along on other lines. 
The genus originated in the Temperate life zone in its colder 
regions as is shown by the most primitive species the Homalobi, of 
which very few are found in hot regions and all are perennials. 
I have tried to retain the old sectional names wherever this does 
not cause confusion. The new sectional] names are taken from the 
leading species in the group. In subdivisions of sections, wherever 
groups are well defined I have named them in the same way. 
That Astragalus is closest related to Oxytropis, Crotalaria and 
Colutea is evident, but the Homalobi remind one much of Hosackia 
end Lathyrus, the pods splitting and curling in the same way in 
several species. 
I take the Homalobi to represent the lowest forms and A. cam- 
restris the lowest species. From this an early offshoot is the 
Triphylli presaged by the caespitose species A. simplicifolius and 
carried much farther in A. montanus. These are Plains adaptations. 
The Lotiflori represents another digression toward the inflated forms 
represented in the lowest group the Debiles also an earlier offshoot 
cf the Homalobi and which reached considerable alteration in the 
Inflati of the arid and variably alkaline and hot deserts, and in 
the Sparsiflori of the more moist and sweet esoiled mountains which 
group also passes into the Alpini of the high and Arctic regions. Tt 
should be noticed that regions with deep snow produce thin-walled 
pods. Regions with little or no snow and with a tendency to alkali 
and a warm climate favor differentiation into thin-walled and in- 
flated pods in offshoots of the Debiles. 
i The Homalobi again branch into the Collini which represents one 
of the two great lines of differentiation. The Collini branch into the 
Podo-sclerocarpi of the Columbia Basin and northern Great Basin 
t x 3 t 
