98 ROSACEAE. 



EXOCHORDA. Pearl Bush. 



Deciduous shrubs with brownish wood with minute diffused 

 ducts, somewhat more crowded in spring, and fine medullary 

 rays ; moderately slender terete twigs ; round homogeneous pale 

 pith ; alternate slightly raised crescent-shaped leaf-scars with 3 

 bundle-traces ; no stipule scars ; oblong ovoid sessile solitary 

 erect buds, with about 8 exposed scales ; moderate simple entire 

 or few-toothed rather short-stalked leaves ; rather large perfect 

 polypetalous perigynous green-centered white flowers clustered 

 at ends of the branches ; and small star-shaped bony fruits. 

 Leaves nearly elliptical, whitened beneath. E. racemosa. 



SIBBALDIA. 



Small matted perennials, woody only at base, with palmate 

 trifoliolate long-petioled basal leaves ; small perfect polypetalous 

 yellow flowers in stalked corymbose clusters ; and several akenes 

 in each persistent calyx. 

 Leaflets cuneate, crenately toothed at end. S. procumbens. 



POTENTILLA. Cinquefoil. 



Usually perennial herbs ; a few deciduous shrubs with 

 brownish wood with minute diffused ducts, somewhat more 

 sparse in summer, and fine medullary rays ; somewhat angular 

 brown continuous pith ; alternate minute round raised leaf-scars 

 with a single bundle-trace, flanked by persistent stipules ; small 

 ovoid buds ; compound leaves with several rather small leaflets ; 

 perfect open usually yellow polyetalous perigynous flowers with 

 bractlets on the calyx ; and numerous small akenes. 

 Leaves pinnate : leaflets linear, entire. P. f ruticosa. 



Leaflets palmate, 3, notched at end. P. tridentata. 



DRYAS. 



Small matted trailing woody evergreens with rather small 

 alternate slender-stalked simple leaves, white-woolly beneath ; 

 rather large perfect open polypetalous perigynous flowers soli- 

 tary at ends of long erect stalks; and large clusters of long 

 feathery-tailed akenes. 



