484 FABACEAE 



keel about 8 mm. long, nearly twice as long as the banner. Dalca nana elatior 

 "Torr."; Port. & Coult., in part. P. rubescens Coult. & Nels., not D. rubescens 

 S. Wats. Dry soil: Tex.— Colo.— Ariz. Son. Jl. 



10. P. aurea (Nntt.) Britton. Stems few, strigose-canescent; leaflets 5-9, 

 oblong, obovate, or oblanceolate, 6-18 mm. long, obtuse or mucronate, silvery- 

 canescent; spikes 2-7 cm. long; bracts broadly ovate, short-acuminate; corolla 

 yellow, not turning red or purple; keel about i2 mm. long, about twace as long 

 as the banner. Plains and hills: S.D. — Mo.- — Tex. — Colo. Plain. Je-Au. 



15. PETALOSTEMON Michx. Prairie Clover. 



Perennial (all ours), or annual caulescent herbs, with glandular-dotted foli- 

 age. Leaves alternate, odd-pinnate. Flowers perfect, in spikes, not subtended 

 by involucres. Calyx campanulate; teeth short and broad. Corolla white, 

 purple, pink, or yellowish; banner broad, clawed; wing- and keel-petals similar 

 to each other, narrower, distinct, inserted at the mouth of the staminal tube, 

 between the stamens. Stamens 5, monadelphous. Pods short, indehisccnt, 

 mostly 2-ovuled, but 1-seeded. 



Calyx glabrous except the teeth; corolla white. 



Spikes compact; bracts longer than the buds; leaflets 1.5-2.5 cm. long. 



1. P. Candidas. 

 Spikes looser; bracts shorter than the buds; leaflets usually less than 1.5 cm. long. 



2. P. oligophyllus. 

 Calyx pubescent. 



Corolla wMte or yellow; spike long and compact. 



Leaves glabrous; corolla white or ochroleucous. 3. P. compactus. 



Leaves sparingly silky; corolla yellow. 4. P. flavescens. 



Corolla rose or purple, very rarely white. 

 Leaflets mostly 5, linear or nearly so. 



Pubescence of the calyx long silky-pilose; bracts lanceolate, acute; leaflets of 

 the lower leaves oblong, obovate, or cuneate. 

 Bracts glabrous or short-pilose. 5. P. Searlsiae. 



Bracts silky, long-pilose. 6. P. ornatus. 



Pubescence of the calyx dense and short; bracts ovate, villous, with a long 

 subulate glabrous acumination. 

 Leaflets linear, conspicuously glandular-dotted; bracts longer than the 

 calyces. 

 Stem and leaves glabrous or sparingly hairy. 7. P. purpureus. 



Stem and leaves densely villous. 8. P. mollis. 



Leaflets spatulate-Unear, not glandular-dotted; bracts shorter than the 

 calyces. 9. P. pubcscens. 



Leaflets 7-17, oblong. 10. P. villosus. 



1. P. candidus (Willd.) Michx. Stems several, erect, 3-7 dm. high, gla- 

 brous; leaflets 7-9, linear, oblong or oblanceolate, 1-3 cm. long, acute or mucro- 

 nate, glabrous; spike 2-10 cm. long, compact; bracts subulate-tipped; calyx 3 

 mm. long; lobes triangular to lanceolate, shorter than the tube; corolla white. 

 Prairies: Ind. — La. — Tex. — Sask. Plain. Je-Jl. 



2. P. oligophyllus (Torr.) Rydb. Stems erect or decumbent, 3-10 dm. 

 high, branched, glabrous; leaflets 5-9, firm, linear, oblanceolate, or elliptic, acute 

 or mucronate, glabrous; spike oblong, becoming more or less cylindric and looser, 

 1-7 cm. long; bracts with filiform tips; calyx-lobes 3 mm. long, triangular, acute; 

 corolla white. P. gracilis oligophyllu.'^ Ton. Plains, prairies, and canons: Minn. 

 — la. — Tex. — Ariz. — Alta. Plain — Submont. Je-Au. 



3. P. compactus (Snreng.) Sweezy. Stems few, glabrous, 3-8 dm. high; 

 leaflets 5-7, ohlong-oblanceolate or linear-oblong, 8-25 mm. long; spike long- 

 peduncled, cylindric, compact, 4-15 cm. long, about 13 mm. thick; calyx silky- 

 villous, 4 mm. long; teeth lanceolate, acute; corolla ochroleucous. P. macro- 

 stachyus Torr. Sand hills and plains: Neb. — Colo. Plain. Jl-Au. 



4. P. flavescens S. Wats. Stem glabrous, about 3 dm. high; leaflets narrowly 

 oblong, obtuse, 6-12 mm. long, sparingly silky; spike dense, long-peduncled, 

 2.5-4.5 cm. long; calyx silky-villous; teeth subulate. Drv rocky hills: s Utah. 

 Son. Jl. 



5. P. Searlsiae A. Gray. Stem glabrous, branched below, 3-5 dm. high; 

 leaflets 5-7, linear-oblanceolate to cuneate or ovate, obtuse, rounded or retuse at 



