291. 
294. 
295. 
296. 
297. 
298. 
299. 
300. 
301. 
KEYS—LEAVES ALTERNATE 
. Lowest scale central over the leaf-scar: pith 5-angled, 
sometimes spongy. p. 9. Populus. 
Without this combination of characters. 288. 
. With resin-glands or blisters, at least in sheltered 
places. 289. 
Not resinous-glandular. 290. 
. Stipule-scars elongated: resin in blisters. p. 23. Betula. 
Stipule-scars minute or lacking. p. 13. Myrica. 
. Buds distinctly stalked below their lowest scales. 291. 
Buds not stalked except as they begin to develop. 295. 
Leaf-scars 2-ranked: buds pubescent. 293. 
Leaf-scars in more than 2 ranks. 292. 
. Spicy-aromatic. _ p. 72. Benzoin. 
Not aromatic. p. 25. Alnus. 
. Bark flaking: buds. often black. p. 86. Parrotia. 
Buds not exfoliating. 294. 
Fruit in elongated clusters. p. 87. Fothergilla. 
Partly developed fruit in sessile groups. p. 88. Hamamelis. 
Pith 3-sided or much flattened. 296. 
Pith neither 3-sided nor greatly flattened. 297. 
Bud-seales scarcely meeting. p. 25. Alnus. 
Bud-seales overlapping. p. 23. Betula. 
Twigs 3-ribbed below the (usually stipulate) 
leaf-scars. 298. 
Twigs not sharply 3-ribbed from the leaf-scars 
when fresh. 307. 
Twigs green or red, slender: small shrubs. 299. 
Without this combination of characters. 300. 
Twigs green: buds solitary. p. 113. Kerria. 
Twigs red: buds superposed. p. 93. Stephanandra. 
Leaf-scars fringed: buds superposed. p. 137. Cercis. 
Leaf-scars not fringed or else buds not superposed. 301. 
Buds superposed. 302. 
Buds not superposed. 303. 
