310 NORTH AMERICAN FLORA [Volume 24 



2. Orophaca argophylla (Nutt.) Rydb.; Britton, Man. 



ed. 2. 1067. 1905. 



Phaca argophylla Nutt.; T. & G. Fl. N. Am. 1: 342. 1838. 

 Astragalus hyalinus M. E. Jones, Proc. Calif. Acad. II. 5: 648. 1895. 



A pulvinate cespitose perennial, with a short woody caudex; branches about 5 cm. high; 

 leaves 2-3 cm. long, spreading; stipules scarious, broadly ovate, sparingly hairy, about 8-15 

 mm. long; petioles 1-1.5 cm. long; leaflets oblanceolate, 8-15 mm. long, acute or obtuse, 

 silvery-silky; flowers subsessile in the axils of the leaves; calyx densely white-silky, the tube 

 cylindric, about 8 mm. long, the teeth fully 3 mm. long; corolla ochroleucous, 15-18 mm. long, 

 pubescent without; petals almost as in O. caespitosa but shorter; pod ovoid, white-silky. 



Type locality: Upper waters of the Platte. 



Distribution: Western Nebraska, Wyoming, and northeastern Colorado. 



Illustrations: Britt. & Brown, 111. Fl. ed. 2./. 2560; M. E. Jones, Rev. Astrag. pi. 7,f. 25. 



3. Orophaca tridactylica (A. Gray) Rydb. Bull. Torrey Club 

 32:668. 1906. 



Phaca digitala Torr. ; Frem. Rep. 89, hyponym. 1845. 



Astragalus tridaclylicus A. Gray, Proc. Am. Acad. 6: 527. 1865. 



Tragacanlha tridactylica Kuntze, Rev. Gen. 942. 1891. 



Astragalus sericoleucus tridaclylicus M. E. Jones, Contr. W. Bot. 10: 69. 1902. 



A pulvinate-cespitose perennial; stems less than 1 dm. long, densely covered by stipules 

 and old leaf-stalks; leaves 1-6 cm. long, erect; stipules scarious, broadly ovate, 5-8 mm. long, 

 pubescent; petioles 0.5-4 cm. long; leaflets of the early leaves obovate or cuneate, short, those 

 of the later ones oblanceolate, 1-2 cm. long, silvery-silky; peduncles 0.5-1 cm. long; racemes 

 2-10-flowered; calyx silky, the tube 3 mm. long, the teeth subulate, nearly as long; corolla 

 purplish, drying yellowish, about 1 em. long; banner obovate, moderately arcuate; wing 

 slightly shorter, the blade oblanceolate, longer than the claw, with a small auricle ; keel-petals 

 much shorter, the blade broadly lunate, about equaling the claw; pod rounded ovoid, puberu- 

 lent or glabrate, 4-5 mm. long, 1-4-seeded; seeds broadly ellipsoid, yellowish, 2 mm. long, 

 1.5 mm. thick. 



Type locality: Boulder City, Colorado. 



Distribution: Colorado. 



Illustrations: M. E. Jones, Contr. W. Bot. 10: pi. 1; Rev. Astrag. pi. 6. 



4. Orophaca aretioides (M. E. Jones) Rydb. Bull. Torrey Club 

 32:668. 1906. 



Astragalus sericoleucus aretioides M. E. Jones, Contr. W. Bot. 8: 13. 1898. 



A cespitose pulvinate perennial, with a branched woody caudex; branches 4-10 cm. long, 

 densely covered with stipules and old leaf-stalks; leaves crowded, spreading, 1-2 cm. long; 

 stipules scarious, pubescent, broadly ovate; petioles 5-10 mm. long; leaflets oblanceolate, 

 5-10 mm. long, silvery-silky; peduncles 1-5 mm. long; racemes 1-3-flowered; calyx silky, 

 the tube 2.5 mm. long, the teeth subulate, 2.5 mm. long; corolla purplish, with darker veins, 

 in age yellowish, 7-8 mm. long; banner broadly obovate, retuse; wings somewhat shorter, 

 the blades obliquely oblanceolate; keel-petals much shorter, the blades broadly lunate, almost 

 semiorbicular, rounded at the apex; pod similar to that of 0. sericea. 



Type locality: Sweetwater River. Wyoming. 



Distribution: Wyoming and northern Colorado. 



Illustrations: M. E. Jones, Rev. Astrag. pi. 6; Contr. W. Bot. 10: pi. 1. 



5. Orophaca sericea (Nutt.). Britton; Britt. & Brown, 111. Fl. 

 2:307. 1897. 



Phaca sericea Nutt.; T. & G. Fl. N. Am. 1: 343. 1838. 

 Astragalus sericoleucus A. Gray, Am. Jour. Sci. II. 33: 410. 1862. 

 Tragacantha sericea Kuntze, Rev. Gen. 942. 1891. 



A broadly cespitose plant, with a woody caudex; branches 5-20 cm. long, decumbent, 

 much branched, densely covered with stipules and remains of leaves; leaves crowded, 1-2 cm. 



