Keys Leaves Alternate xxvii 



236. With stipule-scars: pith flat or 3-sided. p. 23. Betula. 

 No stipule-scars: pith round. p. 360. Baccharis. 



237. Leaf-scars low, almost straight. p. 123. Rosa. 

 Leaf-scars more or less raised if straight. 238. 



t38. Lateral buds short-ovoid or bluntly conical or oblong. 239. 

 Lateral buds elongated-ovoid or conical. 243. 

 39. With stipule-scars. 240. 

 No stipule-scars. 242. 

 40. Pith minute, flat or 3-sided. p. 23. Betula. 



Pith rounded. 241. 



241. Twigs hairy: bud-scales overlapping. p. 102. Cydonia, 

 Glabrous: buds ovoid, scales subvalvate. p. 242. Stachyurus. 



242. Twigs slender (1mm.): end-bud lacking, p. 109. Photinia. 



i Twigs stouter: usually with end-bud. p. 104. Pyrus. 



3. Pith 5-angled: bud-scales twisted. p. 110. Amelanchier. 

 Without this combination of characters. 244. 

 4. Pith minute, green, flattened or 3-sided. p. 23. Betula. 

 Pith not 3-sided if small. 245. 

 5. Bark exfoliating. .p. 98. Exochorda. 



Bark not exfoliating. 246. 

 6. Buds woolly or gummy, ovoid-oblong. p. 106. Sorbus. 



Buds neither woolly nor gummy. 247. 

 7. Buds narrowly oblong. p. 105. Aronia. 



Buds acutely ovoid: bark bitter. p. 127. Prunus. 



8. Stipule-scars encircling the twig. p. 90. Platanus. 



Stipule-scars not encircling the twig. 249. 

 249. Leaf-scar from the first nearly encircling the bud. 250. 

 Leaf-scar at first on an articular membrane. 252. 

 Sap milky or flowing freely: pith continuous, p. 187. Rhus. 

 Without this combination of characters. 251. 



51. Pith continuous: nodes not swollen. p. 144. Cladrastis. 

 Pith spongy: nodes swollen. p. 245. Dirca. 



52. Somewhat aromatic: twigs dotted. p. 164. Ptelea. 

 Not aromatic: end-bud lacking. 253. 



