438 BOTAJ^]:Y. 



the tube; banner whitish, veined; keel inflexed, with a narrow produced apes; pod oblong-linear 

 curved, pubescent, obcompressed-triangular, dorsal suture intruded, the ventral prominent and cari- 

 nate. — New Mexico and Arizona. 



38. A. Okeganus, Nutt. Dwarf, hirsutish-canescent ; stipules scarcely sheathing ; leaflets obovate, 

 emarginate ; flowers ochroleuoous (?), spicate-capitate upon a short peduncle, rather large ; calyx-tube 

 cylindric, twice longer than the teeth ; ovary septate nearly to the middle ; pod not known.— Eocky 

 Mts., (Nuttall.) 



§ 13. MICEOLOBI. Pod 2-3" long, sessile, coriaceous or cartilaginous, 6-7-ovuled, eUiptic-ovate, 

 either nearly terete and scarcely flattened on the back or broadly concave, always whoUy l-celled, 

 the ventral suture thick and prominent. Perennial, subcinereous ; stems erect or ascending, 

 slender, rather rigid, 1° high or more ; leaflets 5-8 pairs, linear ; lower stipules somewhat united, 

 the rest distinct ; racemes spikelike, many-flowered, virgate ; flowers small, purple, recurved- 

 spreading ; calyx and teeth short. — Missouri and Nebraska to the Eocky Mts. 



39. A. GEACILIS, Nutt. Stems virgate ; leaflets nearly filiform, 7-10" long, obtuse or retuse ; racemes 

 dense, elongated, long-peduncled ; flowers 3" long, pale-purple or whitish ; pods spreading, coriaceous, 

 strongly concave on the back, white-hairy, at length glabrous, transversely rugose-veined, the ventral 

 suture subacute, 



40. A. MicHOLOBUs, Gray. Stems diffuse; leaflets 4-6" long, linear or oblong-linear, emarginate; 

 racemes rather short and usually loosely-flowered; flowers deep-purple, 4" long; pods reflexed, thick- 

 cartilaginous, puberulent, finely rugulose, turgid, a little flattened on the back, the ventral suture very 

 thick. 



§ 14. OEOBOIDEI. Pod stipitate or sessile, coriaceous or nearly membranous, scarcely or not at all 

 obcompressed, l-celled or imperfectly 2-celled, with the dorsal suture more or less deeply impressed 

 or inflexed. Caulescent, slender, glabrous or pubescent ; stipules nearly free, distinct except the 

 lowest ; flowers in short often spikelike racemes, or few in small heads, rather small or middle- 

 sized, purple to white, spreading ; calyx short. 



' Northern, perennial, ascending ; flowers pedicelled, mostly racemed ; pods oblong, stipitate, (stipg 

 very short in A. oroboides and sparsiflorus,) subsecund, usually pendent, the ventral suture rather 

 prominent. 



(a.) Pod membranous, glabrous or finely puberulent, slightly more compressed laterally, l-ceUed with 

 a very narrow rudimentary septum from the straight dorsal suture, the ventral suture gibbous. 



(].) Pod long-stipitate, not sulcate, cross-section oval; leaflets never retuse, the lowest pair approxi- 

 mate to the stipules except in the lower leaves ; flowers in a close raceme, white or bluish, keel 

 violet. 



41. A. ABOEiomuM, Eich. Puberulent or subvillous ; pod semi-elliptic. See page 70. 



42. A. GLABRiuscuLUS, Gray. Glabrous or with short scattered hairs ; leaflets thinner, green, linear- 

 lanceolate and subacute, or oblong and obtuse at both ends ; ovary glabrous ; pod lanceolate-subfalcate, 

 attenuate into a stipe 2-3 times exceeding the calyx ; otherwise like the last, of which it is "probably 

 only a variety."— Eocky Mts. of British America and Colorado. 



(2.) Pod short-stipitate, not dorsally sulcate or very obsoletely so, (the cross-section obovate, retuse,) 

 minutely darkish-pubescent ; leaflets subretuse ; flowers white, 4" long. 



43. A. EoBBiNSli, Gray. Subglabrous ; stems 1° high, suberect ; leaflets 3-5 pairs, oval or oblong ; 

 raceme close, oblong ; calyx-teeth much shorter than the tube ; pods thin-membranous, oblong, straight 

 or somewhat incurved, 6" long, very obtuse and abruptly narrowed at base into an included stipe.— Ver- 

 mont. See page 70. 



(6.) Pod more coriaceous, black- or rarely cinereous-pubescent, more or less triangular and semi- 



2-celled, the dorsal suture sulcate-impressed. 

 (1.) Pod somewhat symmetrical, short, oblong lens-shaped, slightly compressed, cross-section obcor- 



date, the ventral suture a little the more gibbous. 



44. A. OROBOIDES, Hornem., Var. Amkricanus, Gray. Subcinereous-puberulent ; stems suberect, 

 1-ip high; leaflets 5-7 pairs, oblong and oval or often linear-oblong, scarcely retuse; flowers 3-4" long, 

 in a long secund raceme, violet or purple, the wiags exceeding the keel ; pod 5-6" long, 3-4 times longer 

 than the calyx, the appressed pubescence usually gray, moderately sulcate, few-seeded; stipe very 

 short. — Labrador, on the Saskatchewan, and in the Eocky Mts. to Colorado. 



(2.) Pod triangular, more impressed, the cross-section deeply oboordate, rather straight or incurved, 

 gibbous on the back. Leaves sometimes retuse or subemarginate. 



45. A. ALPiNUS, L. Hairy-pubescent or glabrous, diffuse; leaflets 6-12 pairs, oval or obloiig; ra- 



