ACERACEAE 



Rocky Mountain Maple. Dwarf Maple 

 Acer glabrum Torr. 



HABIT. A shrub or small tree rarely 20-30 feet high and 

 6-12 inches in diameter; narrow crown with small branches. 



LEAVES. Mostly 3-5-lobed and simple, but sometimes 

 divided into 3 leaflets; 3-5 inches long; sharply and doubly 

 serrate; glabrous; thin; dark green above, paler below. 



FLOWERS. Mostly dioecious; in loose, racemose corymbs: 

 petals yellow-green; appearing after the leaves. 



FRUIT. Key with slightly spreading or nearly erect wings. 

 %-% inch long; glabrous; often rose-colored in summer. 



TWIGS. Slender; glabrous; becoming bright red-brown. 

 Winter buds: acute, Vq-IA: inch long, bright red. 



BARK, Thin, smooth, dark red-brown. 



WOOD. Unimportant; heavy; hard; close-grained. 



SILVICAL CHARACTERS. Rather tolerant; in moist loca- 

 tions; the northwestern form (var. douglasii Dibb.) has shallower 

 leaf sinuses. 



* * * 



Vine Maple 



Acer circinatum Pursh 



HABIT. A shrub or small tree rarely 35 feet high; often 

 vine-like or prostrate and forming dense thickets; irregular 

 crown. 



LEAVES. Simple; orbicular; 7-11 lobed; 2-6 inches long; 

 lobes sharply doubly toothed; glabrous; light green above, 

 paler below; turning red or orange in the autumn. 



FLOWERS. Polygamo-monoecious; in loose corymbs; petals 

 greenish-white, shorter than red calyx: appearing with the 

 leaves. 



FRUIT. Key with widely divergent wings lYi inches long; 

 glabrous; red; maturing in late autumn. 



TWIGS. Slender; glabrous; green to red-brown. Winter 

 buds: terminal Yq inch long, obtuse, bright red. 



BARK. Thin; smooth or with shallow fissures; bright red- 

 brown. 



WOOD. Unimportant; heavy and hard; used for handles 

 and fuel. 



SILVICAL CHARACTERS. Very tolerant; moist stream 

 banks. 



[301] 



