236. 
237. 
238. 
239. 
240. 
241. 
242. 
243. 
244. 
245. 
246. 
247. 
| 248. 
249. 
250. 
251. 
252. 
KEYS—LEAVES ALTERNATE xxvii 
With stipule-scars: pith flat or 3-sided. p. 23. Betula. 
No stipule-scars: pith round. p. 360. Baccharis. 
Leaf-scars low, almost straight. p. 123. Rosa. 
Leaf-scars more or less raised if straight. 238. 
Lateral buds short-ovoid or bluntly conical or oblong. 239. 
Lateral buds elongated-ovoid or conical. 243. 
With stipule-scars. 240. 
No stipule-scars. 242. 
Pith minute, flat or 3-sided. p. 23. Betula. 
Pith rounded. 241. 
Twigs hairy: bud-scales overlapping. p. 102. Cydonia. 
Glabrous: buds ovoid,scales subvalvate. p. 242. Stachyurus. 
Twigs slender (1mm.): end-bud lacking. p. 109. Photinia. 
Twigs stouter: usually with end-bud. p. 104. Pyrus. 
Pith 5-angled: bud-scales twisted. p. 110. Amelanchier. 
Without this combination of characters. 244. 
Pith minute, green, flattened or 3-sided. p. 23. Betula. 
Pith not 3-sided if small. 245. 
Bark exfoliating. p. 98. Exochorda. 
Bark not exfoliating. 246. 
Buds woolly or gummy, ovoid-oblong. p. 106. Sorbus. 
Buds neither woolly nor gummy. 247. 
Buds narrowly oblong. p. 105. Aronia. 
Buds acutely ovoid: bark bitter. p. 127. Prunus. 
Stipule-scars encircling the twig. p. 90. Platanus. 
Stipule-scars not encircling the twig. 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. 
Pith continuous: nodes not swollen.  p. 144. Cladrastis. 
Pith spongy: nodes swollen. p. 245. Dirca. 
Somewhat aromatic: twigs dotted. p. 164. Ptelea. 
Not aromatic: end-bud lacking. 253. 
