206 ACERACEAE. 



24. Twigs stout (4-6 mm.), green. 



(Oregon maple). A. macrophyllum. 

 Twigs moderate or slender. 25. 



25. End-bud rather long (over 5 mm.). 



(Sycamore maple). A. pseudoplatanus. 

 Buds distinctly smaller. 26. 



26. Exposed scales about 6: buds as thick as long. 



(Tartarian maples). 27. 

 Exposed scales about 8. (Field maples). 28. 



27. Buds blackish: twigs dark. A. tataricum. 

 Buds red-brown or paler. A. Ginnala. 



28. Buds gray-woolly, at least above. A. campestre. 

 Buds glabrate, becoming dark. A. monspessulanum. 



29. Buds glabrous. 30. 



Buds more or less silky or hairy and dull. 31. 



30. Buds stout, prismatic: end-bud often lacking. 



A. carpinifolium. 

 Buds fusiform, terete, very acute. A. mandshuricum. 



31. Twigs loosely hairy above. A. nikoense. 

 Twigs glabrescent. 32. 



32. Twigs 3-4 mm. thick: buds 10 mm. long. A. diabolicum. 

 Twigs slenderer and buds smaller. 33. 



33. Buds moderate (the terminal 5 mm. long). 34. 

 Buds small (scarcely 2X3 mm.). 35. 



34. Twigs and buds dull straw-color, hairy. 



(Black maple). A. nigrum. 

 Twigs glossy buff: buds darkening, glabrate. 



(Sugar maple). (4). A. saccharum. 



35. Bark of trunk finally rough. A. floridanum. 

 Bark persistently smooth and white. A. leucoderme. 



