84 TREES OF THE NORTHERN UNITED STATES 
Genus 25. ACER. 
Trees, or rarely shrubs, with simple, opposite, and almost 
always palmately lobed leaves, which, in our species, are 
always deciduous. Flowers small and usually dull-colored, 
in clusters. Fruit double-winged and 2-seeded, in some 
species hanging on the tree till the leaves have fallen; 
in others dropping off early in the spring. The species 
differ much in the spreading of the wings of the fruit. 
Wood light-colored and medium hard; bark rather 
smoothish, but in large trees with longitudinal cracks. 
* Leaves slightly or not lobed. ..............0.. 00 ces cee eee 13. 
* Leaves about 3-lobed (rarely 5-lobed); shrubs or small trees. 
(A.) 
A. Leavesserratescciyesssacssacceseneeveie seaweed Mee as 1, 2. 
A. Leaves somewhat sinuate, not at all serrate; juice milky.10. 
* Leaves 5-, rarely 3-lobed. (B.) 
B. The lobes acute, irregularly but quite fully serrate; juice not 
milky. (C.) 
C. The fruit in corymbs, dropping early; American species. 
(D.) 
D. Leaf-notches somewhat rounded; tree large; limbs 
drooping on old trees........... 6. cece cece eee 3. 
D. Leaf-notches acute; tree‘small ............... ...0.. 4, 
C. Fruit in hanging racemes, remaining on the tree till au- 
tumn; leaves thickish ...............0.0 00 cesses e eee 5. 
B. The lobes acute; sparingly or not at all serrate. (E.) 
By Juice not milky: «4. se: sessmwconser anes ieee es sceeeseyey 6. 
E. Juice milky at the bases of the leaves................ 8, 9. 
B. The lobes obtuse and sinuate ........... ce cece eee 10. 
* Leaves 5- to 7-lobed. (F.) 
F. Lobes fully serrate........ 0... cece ccc e eee erences 11. 
F. Lobes sparingly serrate. (G.) 
G, Juice milks wis c2oecege een sets dewalt es 54 bases 8, 9. 
G. Juice not milky; leaves 8 to 10 in. broad.............. 7 
F. Lobes somewhat sinuate, not serrate; juice milky ....... 10. 
* Leaves with 7 or more lobes .............6... 00. eee e eens 11, 12. 
1. Acer spicatum, Lam. (Mountain Mapue.). Leaves with 3 
(rarely 5) coarsely serrated, taper-pointed lobes, with slightly cor- 
date base; downy beneath. Flowers greenish-yellow, in eérect, 
