10. 
11, 
19. 
20. 
21. 
23. 
ACERACEAR. 205 
Leaf-scars with a membranous wing at top. 11. 
Leaf-scars not winged: twigs purplish. 
(Vine maple). A. circinatum. 
Scales blunt: buds and twigs usually green. A. japonicum. 
Scales mucronate: buds and twigs purplish. 
A. Sieboldianum. 
. Exposed scales about four. 13. 
Exposed scales six or more. 23. 
. Leaf-scars meeting in a point. 14. 
Leaf-sears connected by a transverse line. 20. 
. Buds gray-hairy: leaf-scars with minute red _ glands 
above. (Box elder). 15. 
Buds glabrate: leaf-scars not glandular. 18. 
. Twigs very glaucous. 16. 
Twigs little if at all glaucous, or else puberulent. 17. 
. Twigs green when rubbed. (2). A. Negundo. 
Twigs violet when rubbed. A. Negundo violaceum. 
. Twigs olive, puberulent. - A. Negundo interius. 
Twigs bright green, glabrous. A. Negundo Nuttallii. 
. Twigs moderate (4 mm.): buds large. 
(Norway maple). A. platanoides. 
Twigs slender (3 mm.): buds small. 19. 
Bud-seales purplish, brown-bordered. A. pictum. 
Bud-seales light brown. A. truncatum. 
Twigs woolly near the end. 
(Woolly red maple). A. Drummondii. 
Twigs glabrous. 21. 
Buds collaterally multiple toward spring. 22. 
Buds always solitary. 27. 
. Bark of trunk rough but not flaking. 
(Red maple). (3). A. rubrum. 
Bark flaking, leaving brown areas. ~ 
(Silver maple). A. saccharinum. 
Buds ovoid, usually very blunt. 24. 
Buds conical or acute. 29. 
