20 RYDBERG: NOTES ON FABACEAE—IIT 
carpus A. Gray evidently does not belong there. A. Halli A. 
Gray is just as good a species of Phaca as of Homalobus. The 
disposition of A. flexwosus and its allies is harder to settle. In 
general habit it resembles some of the species of Homalobus 
but the pod is terete, and it would be better to limit that genus 
to the flat-podded species. 
KENTROPHYTA Nutt. 
The genus Kentrophyta was established in 1838, in Torrey & 
Gray’s Flora of North America. It was based on two species, 
K. montana and K. viridis, with an unnamed variety of the for- 
mer. Gray merged the genus into Astragalus and united the 
species under the name A. Kentrophyta A. Gray. Thirty-three 
years later Watson described a species under the name A. 
tegetarius and a variety under the name A. Kentrophyta elatus, 
but failed to see the close relationship of the former to A. 
Kentrophyta, placing it in a far remote section of Astragalus. 
In 1899 A. Nelson added a fourth species, A. aculeatus, to the 
group. The remaining species have been described by the present 
author. : 
The species are very closely related and some botanists are 
inclined to regard them as a single variable species. If so this 
would have at least eight marked varieties. 
I. KENTROPHYTA MONTANA Nutt. This species, the type 
of the genus, is characterized by the scarious stipules, united 
high up, long-acuminate or cuspidate, but scarcely spinulose, by 
the subulate leaves, scarcely narrowed at the base and by the 
very compressed pod. It is the most eastern and northern and 
the best known of the species, ranging from Saskatchewan and 
Alberta to Colorado and western Nebraska. Sheldon changed the 
name to Astragalus viridis, mistaking it for Kentrophyta viridis. 
SASKATCHEWAN: Gull Lake, J. Macoun; Cypress Hills, 27; 
Milk River, rozgz. 
Montana: Yellowstone, Hayden. 
_SoutH Dakota: White River, Wallace; Smithville, 7. A. 
Williams. 
Wyominc: Bitter Creek, Britton; ‘Rocky Mountains,” 
Nuttall; Pine Bluffs, A. Nelson 3621; Badger, 2751; Upper 
Platte, Geyer 123. 
