62 LEGUMINOS^E. (PULSE FAMILY.) 



6. Pod coriaceous, obovoid, straight, short-stipitate, dorsally sulcate, ventral 

 suture rather prominent, completely 2-celled. Low, caulescent : flowers very 

 small, white or cream-color, tinged with purple. 



13. A. Brandegei, Porter. Canescent with minute appressed hairs : 

 branching from a somewhat woody base : leaflets linear : racemes on long 

 peduncles, loosely few-flowered : pod hairy. Fl. Colorado, 24. Banks of the 

 Arkansas near Canon City, Colorado, Brandegee. 



7. Pod exsert-stipitate, pendent, very glabrous, straight or falcate, narrow, more 

 or less triangular, very deeply sulcate dorsally, the suture intruded to the middle 

 or beyond. Stems erect, stout, sulcate, very leafy : flowers in long crowded 

 racemes, rather large. 



14. A. Drummondii, Dougl. Softly villous : calyx scarcely gibbous at 

 base, black-hairy: corolla white: pod long-linear, terete, cross-section obcordately 

 2-lobed. From Colorado to Nebraska and the Saskatchewan. 



15. A. SCOpulorum, Porter. Pubescent with appressed hairs: calyx gib- 

 bous at. base, pilose with blackish hairs : corolla yellow or ochroleucous : pod 

 oblong, becoming arcuate with age, sharply 3-angled, the dorsal suture with an 

 acute sulcus on each side. Fl. Colorado, 24. A. subcompressus, Gray. Cen- 

 tral and Southern Colorado. 



1 6. A. r aceniOSUS, Pursh. Appressed pubescent, glabrate : calyx strongly 

 gibbous at base, whitish-puberulent : corolla white : pod lance-oblong, cross-section 

 somewhat equally triradiate. From Colorado to Nebraska and Idaho. 



8. Pod sessile, coriaceous, obcom pressed, ivith the impressed dorsal suture more 

 or less approaching the ventral, but not 2-celled. Low or prostrate, with a fine 

 hoary pubescence : flowers spicate, deep yellow. 



17. A. flavus, Nutt. Diffuse: stipules sheathing the stem and base of 

 the petiole, oblique : leaflets linear : pod half-included, hoary, ovate, straight. 

 W. Wyoming, Parry, and westward. 



9. Pod 2 to 3 lines long, sessile, elliptic-ovate, always wholly one-celled, the 

 ventral suture thick and prominent. Subcinereous : stems slender, rather 

 rigid, a foot high or more : lea/lets 5 to 8 pairs, linear : racemes spike-like : 

 flowers purple to whitish. 



18. A. gracilis, Nutt. Stems virgate: leaflets nearly filiform: racemes 

 dense, elongated, long-peduncled : flowers pale purple or whitish : pods spreading, 

 coriaceous, strongly concave on the back, white-hairy, at length glabrous, trans- 

 versely rugose-veined. From Colorado to Nebraska and Missouri. 



19. A. microlobus, Gray. Stems diffuse: leaflets shorter, linear or 

 oblong-linear : racemes rather short and usually loosely flowered : flowers deep 

 purple : pods reflexed, thick-cartilaginous, puberulent, finely rugulose, a little 

 flattened on the back, the ventral suture very thick. Proc. Am. Acad. vi. 

 203. From the Rocky Mountains to Missouri and Nebraska. 



10. Pod stipitate, coriaceous or nearly membranous, scarcely or not at all obcom- 

 pressed, 1-celled or imperfectly 2-celled. Caulescent, slender: flowers in 

 short often spike-like racemes, or few in small heads, purple to white, spreading, 



* Pod membranous, glabrous or pubescent, slightly more compressed laterally, 

 1-celled with a very narrow rudimentary septum from the straight dorsal suture, 

 the ventral suture gibbous. 



