ROSE FAMILY 151 



(y) Leaflets 3-5; stems trailing, leafy Rubus 

 y. Leaves pinnate of many leaflets ; stems 



leafless Horkelia 



(2) Flowers yellow, pink or purple, occasion- 

 ally cream-colored or white 



(a) Stamens 5; pistils 5-10 



x. Petals white ; leaves many-cleft into 



linear segments Chamaerhodus 



y. Petals yellow, small ; leaves of 3 leaflets Stbbaldia 



(b) Stamens 10-many; pistils many 



x. Styles long, persistent and usually 

 hooked or plumy in fruit 

 (x) Styles naked or plumy, bent or 



jointed; flowers yellow or purplish Geum 

 (y) Styles naked or plumy, straight, not 

 jointed ; flowers yellow or pink- 

 purple SlEVERSIA 

 y. Style short, falling away from the ripe 

 achenes 

 (x) Styles attached at the base of the 



achenes; leaflets not silvery-silky Drymocallis 

 (y) Styles lateral, attached near the 

 middle of the achene ; leaflets sil- 

 very-silky Argentina 

 (z) Styles terminal, attached near the 

 tip of the achenes 

 m. Flowers yellow Potentilla 

 n. Flowers red-purple Comarum 

 2. Shrubs 



a. Leaves simple 



(1) Flowers solitary, or 2-3 in a cluster 



(a) Petals white ; 



x. Stamens and pistils many ; leaves round- 

 ish, 3-5-lobed Rubus 

 y. Stamens 10; pistils 5; leaves entire Kelseya 



(b) Petals yellow 



x. Leaves 3-7-pinnatifid ; style becoming 



long and plumy Cowan i a 



y. Leaves 3-lobed at tip ; style not long 



and plumy Purshia 



(c) Petals none 



