256 NORTH AMERICAN FLORA [Volume 24 



10. Kentrophyta aculeata (A. Nelson) Rydb. Bull. Torrey Club 

 32:665. 1906. 



Kentrophyta montana Nutt.; T. & G. Fl. N. Am. 1: 353. 1838. 

 Astragalus aculeatus A. Nelson. Bull. Torrey Club 26: 10. 1899. 

 Homalobus aculeatus Rydb. Mem. N. Y. Bot. Gard. 1: 249. 1900. 

 Kentrophyta montana Jepson, Man. Fl. PI. Calif. 583, mainly. 1925. 



A perennial, with a cespitose, tufted caudex; stems numerous, decumbent, intricately 

 branched, 0.5-3 dm. long, hirsutulous-canescent with ascending hairs; stipules scarious, hirsute 

 along the margins, deltoid, acuminate or often long-attenuate and somewhat pungent, 4-6 mm. 

 long; leaves 1-1.5 cm. long, spreading; leaflets 5-7, linear-lanceolate, narrowed at each end, 

 hirsutulous on both sides, green, 5-8 mm. long, 1-1.5 mm. wide, spinulose-tipped; peduncles 

 2-10 mm. long or less, 1-3-flowered; calyx hirsutulous, the tube 2.5 mm. long, the lobes subu- 

 late-filiform, 2 mm. long; corolla purple, 5-7 mm. long; pod ovoid, 5 mm. long, 2.5 mm. wide, 

 hirsutulous, compressed; seeds 2.5 mm. long, obliquely reniform. 



Type locality: Big Horn Mountains, near Dome Lake, Wyoming. 

 Distribution: Montana to Colorado, northern Utah, and California. 



Illustrations: M. E. Jones, Rev. Astrag. pi. 5 (as A. monlanus var. legetarius); Jepson, Man. 

 Fl. PI. Calif. /. 552 (as K. montana). 



33. HOMALOBUS Nutt.; T. & G. Fl. N. Am. 1: 350. 1838. 



Perennial herbs. Leaves pinnate, sometimes, however, reduced to the terminal leaflets, 

 or the lateral leaflets reduced, linear or filiform, and the terminal one similar to and continuous 

 with the rachis. Flowers in axillary racemes. Calyx from campanulate to cylindro-cam- 

 panulate, 5-toothed. Corollas white to purple. Banner obovate, usually strongly arched, 

 usually with a very short claw. Blades of the wings obliquely oblanceolate or obovate, with a 

 reflexed basal auricle, about equaling the claw. Keel-petals shorter, the blade broader and 

 shorter, from round to acute at the apex. Stamens diadelphous (9 and 1), the sheath straight 

 to near the apex, the free portion of the filaments upcurved. Style glabrous, arched upwards 

 near the apex, the stigma minute. Pod elliptic to linear in outline, sessile to slender-stipitate, 

 compressed laterally, mostly flat, both sutures being prominent, especially when the pod is 

 more turgid, the sutures neither inflexed nor produced into a false partition. Seeds obliquely 

 reniform, with a deep-seated hilum. 



Type species, Homalobus dispar Nutt. 



Leaves unifoliolate or some 3-foliolate or (in H. delrilalis) 5-foliolate; plant pul- 



vinate-cespitose ; pod sessile. 1. Simplicifolii. 



Leaves several-foliolate; plant not pulvinate-cespitose. 



Pod sessile or short-stipitate, the stipe rarely exceeding the calyx. 

 Legume oval, ovate, broadly oblong, or elliptic. 



Pod without long black hairs. 2. Tenelli. 



Pod with long black hairs. 3. Bourgoviani. 



Legume linear, 1.5 cm. long or more. 4. Campestres. 



Pod long-stipitate, the stipe decidedly longer than the calyx. 



Calyx not gibbous at the base, less than half as long as the corolla; pod 

 membranous. 

 Pod pendulous. 5. Stenophylli. 



Pod erect on an upcurved pedicel. 6. PorrECTI. 



Calyx strongly gibbous at the base, more than half as long as the corolla; 



pod more coriaceous. 7. Collini. 



1. Simplicifolii 



Corolla purple or pink ; calyx-teeth about as long as the tube; pod nearly flat, 

 thickest along the middle. 

 Corolla about 1.5 cm. long; leaves mostly 3-5-foliolate. 1. H. delritalis. 



Corolla less than 1 cm. long; leaves mostly 1-foliolate or simple. 



Peduncles 3-10-flowered; bracts ovate to lanceolate, shorter than the 

 flowers; pod oblong. 

 Pod long-acute; bracts narrowly lanceolate; leaves usually nar- 

 rowly oblanceolate. 2. H. caespilosus. 

 Pod abruptly acute; bracts short, ovate to lanceolate, scarious; 



leaves oblanceolate or spatulate. 3. H. brachycarpus. 



Peduncles 1 -flowered; bracts subulate, longer than the flowers; pod 



lanceolate. 4. H. uniflorus. 



Corolla ochroleucous or whitish; calyx-teeth about half as long as the tube; 

 pod lanceolate in cross-section, thickest near the lower suture. 



