388 



FABACEAE. 



Vol. II. 



2. Orophaca argophylla (Nutt.j Rydb. Sil- 

 very Milk Vetch. Fig. 2560. 



Phaca argophylla Nutt. ; T. & G. Fl. N. A. i ; 34^- 1838. 



Astragalus hyalinns M. E. Jones, Proc. Cal. Acad. II. 

 5: 648. 1895. 



Orophaca argophylla Rydb. in Britton, Man. Ed. 2, 1067. 

 1905. 



Similar to the preceding species, but the leaflets 

 relatively shorter and broader. Stipules scarious ; 

 corolla about 5" long, pubescent outside; calyx-teeth 

 a little shorter than the tube. 



In dry soil, Nebraska and Wyoming. May-July. 



3. Orophaca sencea (Nutt.) Britton. 



Phaca sericea Nutt. ; T. & G. Fl. N. A. i : 343- 1838. 



Astragalus sericoleucus A. Gray, Am. Journ. Sci. 

 (II.) 33: 410. 1862. 



Orophaca sericea Britton, in Britt. & Brown, HI. Fl. 

 2 : 307. 1897. 



Villous-pubescent, densely tufted, and spread- 

 ing on the ground from a deep root, the stems 

 3'-4' long. Leaves short-petioled, 3-foliolate ; leaf- 

 lets oblong or oblanceolate, acute or obtusish at 

 the apex, narrowed or cuneate at the base, 2"-5" 

 long; peduncles slender, 2-6-flo\vered, equalling or 

 exceeding the leaves; flowers bluish-purple, about 

 3" long; pod i-celled, sessile, ovoid-oblong, coria- 

 ceous, acute, villous-pubescent, about 3" long, 

 partly enclosed by the calyx. 



In dry, sandy or rocky places, Nebraska to Wyo- 

 ming and Colorado. May-July. 



Hoary Milk Vetch. Fig. 2561. 



31. OXYTROPIS DC. Astrag. 19. 1802. 



[Aragallus Neck. Elem. 3 : 12. Hyponym. 1790.] 



[Spiesia Neck, Elem. 3: 13. Hyponym. 1790.] 



Herbs, sometimes shrubby, and mostly acaulescent, with odd-pinnate leaves, and racemose 

 or spicate flowers. Calyx-teeth nearly equal. Petals clawed; standard erect, ovate or oblong; 

 wings oblong ; keel erect, shorter than or equalling the wings, its apex mucronate, acuminate 

 or appendaged ; stamens diadelphous ; anthers all alike; style filiform. Pod sessile or stipitate, 

 2-valved, i-celled, or more or less 2-celled by the intrusion of the ventral suture. [Greek, 

 referring to the sharp-pointed keel of the corolla.] 



About 130 species, natives of the north temperate zone. In addition to the following, some 20 

 others occur in the western and northwestern parts of North America. Type species : Oxytropis 

 montana (L.) DC. 



Leaves simply pinnate. 



Plants i'-4' high ; heads few-flowered. 



Pod membranous, pubescent, much inflated, i -celled. 

 Pod coriaceous, ovoid, little inflated, pubescent, partly 2-celled. 

 Calyx gray-pubescent; leaflets 7-9, oblong. 

 Calyx dark-pubescent ; leaflets 7-21, linear. 

 Plants 6'-i8' high ; heads or spike-like racemes many-flowered. 

 Sparingly pubescent ; flowers 8"-9" long ; pods papery. 

 Silky-pubescent ; flowers 9"-i5" long ; pods coriaceous. 

 Leaves pinnate, the leaflets verticillate. 



Pod scarcely longer than the calyx, its tip spreading. 

 Pod 2-3 times as long as the calyx, its tip erect. 



1. O.podocarpa. 



2. O. miilticeps. 



3. O. arctica. 



4. O. campestris. 



5. O.Lamberti. 



6. O. splcndens. 



7. O. Belli. 



