PEA FAMILY 487 



Calvx-tcctli subulate, fully as long as the tube. 



Plant ai)])rissuci-])ubescent, cespitose and much branched. 

 Stoiu ;usc<'n(iing. 



Inflorescence scarcely equalling the leaves; pod 2-2. .5 cm. 

 long ; corolla ocliroleucous. 15. P. Candolleana. 



Inflorescence exceeding the leaves; pod 12-15 mm. long; 

 corolla purple. 16. P. cerussala. 



Stem decumbent. 17. P. serpens. 



Plant with short spreading pubescence; stem simple, elongate. 



18. P. Silerana. 

 Pod 8-12 mm. long. 



Stem slender and much branched, usually more than 1 dm. high; leaflets more 

 than 5 mm. long, flat, oblong, oval, or obovate. 

 Leaflets 5-11 pairs. 



Plant sUghtly strigose. 



Pod ovoid; plant 3-6 dm. high; racemes many-flowered. 



19. P. Bodinii. 



Pod ellipsoid; plant iisually less than 3 dm. high; racemes few- 

 flowered. 20. P. leptalea. 

 Plant densely liirsutuloiis. 18. P. Silerana. 

 Leaflets 4-6 pairs; plant more or less grayish-pubescent; pod globose-ovoid. 



21. P. microcystis. 

 Stem densely pulvinate-cespitose, with a thick caude.x-, only a few centimeters 

 high; leaflets minute, linear or lanceolate, conduplicate, 1-4 mm. long. 

 Rachis of the leaves not spinose; pod slightly puberulent, mottled, 1 cm. 



long. 22. P. jejuna. 



Rachis of the leaves spinose; pod white-pubescent, 4-6 mm. long. 



23. P. humillima. 

 Upper suture of the pod straight or curved upwards, acute; pod in cross-section obovate, 

 triangular-obovate, or slightly cordate. 

 Plant, including the pods, perfectly glabrous, 2 dm. high or more; pods stipitate, 

 somewhat leathery. 

 Corolla oclu-oleucous ; caly.x-teeth nearly equalling the tube. 24. P. Beckwiihtt. 

 Corolla pm-ple; calyx-teeth much shorter than the tube. 25. P. arlemisiarum. 



Plant, including the pods, more or less hairy; pods sessile. 

 Pods much over 1 cm. long, usually not mottled. 



Pods strongly inflexed; flowers white or ocliroleucous, tinged with purple. 



26. P. pubenlissima. 

 Pods not strongly incurved ; upper suture straight or nearly so ; flowers ocliro- 

 leucous. 

 Plant strictly annual. 



Plant cinereous, with short hairs; pods puberulent. 27. P. annua. 

 Plant, including the pods, grayish hoary. 28. P. sabulonum. 



Plant perennial or at least biennial, cespitose, low. 



Flowers mostly subscssile in the axils of the leaves; racemes if ped- 

 uncled 2-3-flowered; leaflets mostly over 1 cm. long, appressed-hairy. 



29. P. elatiocarpa. 

 Flowers in peduncled several-flowered racemes; leaflets mostly less than 

 1cm. long, loosely hairy beneath, glabrate above. 30. P. lotijiora. 

 Pods about 1 cm. long, mottled; plant diffusely cespitose. 31. P. sesqui flora. 



1. P. americana (Hook.) Rydb. Perennial; stems single or two or three, 

 erect, 3-10 dm. high; leaflets 7-17, oval, elliptic, or oblong, obtuse, thin, 2-4 cm. 

 long, glabrous above, sparingly pubescent beneath; raceme short; calyx glabrous 

 or nearly so; tube campanulate, 4 mm. long; teeth obsolete; corolla ochroleucous, 

 about 12 mm. long; pod glabrous; stipe about 5 mm. long; body ellipsoid, acute, 

 2 cm. long, 7-8 mm. wide. Astragalus frigidus americanus S. Wats. Along 

 streams and in wet copses: Que. — Wyo. — Yukon. Submonl. — Mont. Jl-Au. 



2. P. ampularia (S. Wats.) Rydb. Perennial; stem short, ascending, 

 strigose; leaflets 7-11, obovate, 8-12 mm. long, emarginate, glabrous above, 

 strigose beneath; racemes short and dense; calyx-tube cyHndro-campanulate, 

 5-6 mm. long; teeth nearly obsolete; banner 15-18 mm. long; pod oblong, on a 

 long stipe, glabrous. Astragalus ampullarius S. Wats. Wet places: s Utah. 

 L. Son. Ai>-My. 



3. P. Wetherillii (M. E. Jones) Rydb. Cespitose perennial; stems ascend- 

 ing, 3-4.5 dm. long, glabrous or sparingly strigose above; leaflets 9-17, oval or 

 obovate, rounded or retuse at the apex, 8-10 mm. long, glabrous; inflorescence 

 6-8-flowered; calyx-tube campanulate, 3 mm. long; teeth subulate, 2 mm. long; 

 corolla white, tipped with pink, 8 mm. long; body of the legume ovoid, about 2 

 cm. long, sulcate above, puberulent. A. Wetherillii M. E. Jones. Dry places: 

 Colo. Son. My. 



4. P. allochroa (A. Gray) Rydb. Perennial; stem 1-3 dm. high, strigose. 

 ascending; leaves 5-10 cm. long; leaflets 13-15, olslong, strigose, obtusish, 8-10 



