LEGUMINOSAE (PEA FAMILY) 271 



Leaves digitately 3-5-foliolate . . . . .13. Psoralea. 

 Leaves pinnately 5-many-foliolate. 



Stamens 10 .... 14. Parosela. 



Stamens 5 



Pod a loment, with reticulated indehiscent joints 

 Leaves even-pinnate, terminated by a tendril or bristle. 

 Style slender, with a tuft of hair near the apex 

 Style flattened, hairy on the inner side 



1. THERMOPSIS R. Br. 



15. Petalostemon. 



16. Hedysarum. 



17. Vicia. 



18. Lathyrus. 



Stout perennial herbs with erect clustered stems from running rootstocks. 

 Leaves digitately 3-foliolate; the leaflets entire; stipules conspicuous, free. 

 Flower large, yellow, in racemes. Calyx campanulate, cleft to the middle. 

 Standard shorter than the oblong wings, the sides reflexed; keel nearly 

 straight, as long as the wings. Stamens distinct. Pod linear to oblong- 

 linear, much compressed, shortly stipitate or nearly sessile, straight or in- 

 curved. 



Mature pods straight or only slightly curved. 



Erect and nearly straight . . . . . . . .1. T. montana. 



Spreading, somewhat curved, not recurved or deflexed . . . 2. T. divaricarpa. 

 Mature pods strongly annulately curved and often recurved. 



Leaflets silky-pubescent, at least beneath . . . . . 3. T. rhombifolia. 



Leaflets glabrate 4. T. arenosa. 



1. Thennopsis montana Nutt.* T. & G. Fl. 1: 388. 1840. Stems erect, 

 simple or with a few strict, leafy, sterile branches, more or less silky-pubescent, 

 becoming glabrate, 3-6 dm. high: leaflets oblong-oblanceolate or obovate- 

 oblong, usually acute, sparingly silky-villous beneath, glabrous or nearly so 

 above: flowers alternate or geminate, showy, in a spike 6-12 cm. long: calyx 

 silky-canescent ; its teeth narrow, shorter than the tube: pods silky-canescent 

 or somewhat villous, straight, linear, erect, even appressed, or, if very much 

 crowded, somewhat spreading. (T. stricta Greene, PI. Baker. 3: 34. 1901.) 

 "High valleys in the Rocky Mountains, in bushy places by streams; " west to 

 the Sierras. 



2. Thermopsis divaricarpa A. Nels. Bot. Gaz. 25: 275. 1898. Similar in 

 habit and size, the sterile branches very leafy: leaflets elliptic or obovate, 

 nearly glabrous; the large stipules ovate, somewhat inequilateral, longer than 

 the petiole: pods pubescent when young, at length glabrous, 8-10 cm. long, 

 about 7 mm. broad, slightly curved and becoming widely divaricate. (T. 

 vinetorum Greene, Pitt. 4: 138. 1900.) Often in rather dense patches; stream 

 banks and moist copses; throughout our range. 



3. Thennopsis rhombifolia (Nutt.) Rich. Frank. Journ. App. 13. 1823. 

 Low, erect or ascending, branched, 2-4 dm. high, appressed silky-pubescent, 

 or the leaves sometimes glabrate above: leaflets oval or obovate or rhombic- 

 elliptic, obtuse, sessile; stipules ovate to orbicular: racemes short; flowers 

 15-20 mm. long: pod broadly linear, silky at first and more or less pubescent 

 at maturity, annulately recurved-spreading, several-seeded. (T. annulocarpa 

 A. Nels. Bull. Torr. Bot. Club 26: 239. 1899.) In dry washes and on sterile 

 sandy plains; from Manitoba to Kansas along the eastern boundary of our 

 range. 



4. Thermopsis arenosa A. Nels. 1. c. 276. 1898. Similar in habit and 

 size: stems from the persistent branched bases numerous: leaflets oblong to 

 oblanceolate or even obovate, mostly subacute, nearly glabrous, 3-4 cm. 

 long, 1-2 cm. broad; stipules longer than the petioles, ovate to suborbicular: 

 raceme short even in fruit: pods softly pubescent but at maturity nearly or 

 quite glabrous, widely spreading from the first or even drooping, somewhat 

 curved or at length annulately recurved, often stipitately narrowed at base 

 and constricted at intervals by the aborting of one or more of the seeds. 

 Open sandy washes in the foothills; Colorado and Wyoming. 



* These species are all figured in Bot. Gaz. 25: 275. 



