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. 



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

 Lateral buds elongated-ovoid or conical. 243. 



239. With stipule-scars. 240. 

 No stipule-scars. 242. 



240. 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. 

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



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

 Without this combination of characters. 244. 



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

 Pith not 3-sided if small. 245. 



245. Bark exfoliating. p. 98. Exochorda. 

 Bark not exfoliating. 246. 



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

 Buds neither woolly nor gummy. 247. 



247. Buds narrowly oblong. p. 105. Aronia. 

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



248. 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. 



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

 Without this combination of characters. 251. 



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

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



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

 Not aromatic: end-bud lacking. 253. 



