Genus 19. 



PEA FAMILY. 



371 



7. Petalostemum foliosum A. Gray. Leafy 

 Prairie-clover. Fig. 2518. 



Pctalostemon foliosiis A. Gray, Proc. Am. Acad. 7: 336. 

 1868. 



Kuhnistera foliosa Kuntze, Rev. Gen. PI. 192. 1891. 



Erect, branching, or sometimes simple, glabrous 

 throughout, i°-3° high. Leaves numerous, petioled; 

 leaflets 13-31, close together, short-stalked, linear- 

 oblong or slightly oblanceolate, 4"-7" long, i"-ii" 

 wide, acute or obtuse, mucronate at the apex, nar- 

 rowed at the base ; spikes terminal, long-ovoid or 

 cylindric, I '-2' long, s"-6" thick, densely-flowered ; 

 peduncles short, bracted ; bracts lanceolate, awn- 

 pointed, longer than the glabrous calyx; flowers rose- 

 purple, about 2" long; standard broad, nearly orbicu- 

 lar; wings ajid keel-petals oval; calyx-teeth finely 

 ciliate. 



Along rivers, Illinois, Kentucky (?) and Tennessee. 

 July-Aug. 



8. Petalostemum villosum Nutt. Hairy or 

 Silky Prairie-clover. Fig. 2519. 



Petalostemon riUosus Nutt. Gen. 2: 85. 1818. 

 Dalea villosa Spreng. Syst. Veg. 3: 326. 1826. 

 Kuhnistera villosa Kuntze, Rev. Gen. PI. 192. 1891. 



Ascending or decumbent from a deep root, 

 branching at the base, densely villous or silky- 

 pubescent all over, i''-2° high. Leaves short- 

 petioled or nearly sessile; leaflets 9-17, approxi- 

 mate, linear-oblong or slightly oblanceolate, acute 

 or obtuse and often aristate at the apex, nar- 

 rowed at the base, z's" long, i"-2" wide ; spikes 

 terminal, clustered or solitary, short-peduncled, 

 cylindric, i'-4i' long, s"-6" thick, very dense; 

 bracts lanceolate, acuminate, exceeding the dense- 

 ly villous calyx; corolla rose-purple or rarely 

 white, standard oblong ; wings and keel-petals 

 oblong-obovate. 



Prairies and sandy plains, Wisconsin to Sas- 

 katchewan, Missouri, Texas and Colorado. Aug. 



20. INDIGOFERA L. Sp. PL 751. 1753. 



Herbs, or rarely shrubs, often canescent with hairs affixed by the middle, with odd-pinnate 

 leaves, small stipules, and pink or purple spicate or racemose flowers. Calyx-teeth oblique, 

 nearly equal, or the lower longer. Standard ovate or orbicular, sessile or clawed ; wings 

 oblong; keel erect, somewhat gibbous, or spurred. Stamens mainly monadelphous ; anthers 

 all alike. Ovary sessile or nearly so, i-M-ovuled; style slender. Pod linear, 4-angled (in 

 our species), septate between the seeds. [Name from the yield of indigo by some species.] 



About 275 species, natives of warm and temperate regions. In addition to the following, some 

 7 others occur in the southern and southwestern United States. Type species : Indigofera tinctoria L. 



