26 KEY TO GENERA AND SPECIES 



41. Branches without thorns or spines, side veins 

 of the blade not curving into the apex 

 Arrow-wood, 209. 



41. Branches commonly with a few spines or thorns, 



side veins of the blade curving well up into 

 the apex. Cult, and escaped. Native in 

 Eurasia. (Fig. 48.) Buckthorn, Rhamnus 

 cathartica L. 



42. Branches with thorns 43. 



42. Branches without thorns 44. 



43. Thorns on the side of leafy 



branches Thorn, 159. 

 43. Thorns commonly formed by 

 the pointed ends of branches. 

 Fruit usually with 5 thin- 

 walled seed compartments 

 Apple, Pear (in semi- wild 

 state), 152. 



43. Thorns commonly formed by the pointed ends 



of branches. Fruit with a single seed en- 

 closed in a hard stone Plum, 175. 



44. Side veins nearly straight, usually unbranched. 



(See Figs. 143, 146, 178.) 45- 

 44. Side veins curving or prominently forking. 

 (See Figs. 358, 263, 275054. 



