62 LBGUMINOS^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. — PL Colorado, 24. Banks of the 

 Arkansas near CaHon 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, sidcate, very leafy : flowers in long crowded 

 racemes, rather large. 



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

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

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



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

 bous at base, pdose 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. 



16. A. raoemosus, 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, obcompressed, with 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 : leaflets 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 tittle 

 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, 

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

 the ventral suture gibbous. 



