158 



American Midland Naturalist Monograph No. 4 



Field Guide to the Species 



Leaves lobed (occasionally divided into 3 leaflets in A. glabrum). 

 Flowers in loose spreading clusters; v^estern species. 



Leaves 7- or 9-lobed, green on both sides I. A. circinatum. 



Leaves 3- or 5-lobed, green above, paler below. 



Lobes of leaves not toothed or with a few coarse teeth; petals none; 



found in the Southwest 2. A. grandideniatum. 



Lobes of leaves toothed; petals present; widespread and variable 



species 3. A. glabrum. 



Flowers in narrow elongate clusters 3 to 6 inches long; eastern species found on 

 Isle Royale. 



Leaves 3-lobed about middle; flower-clusters erect or spreading; petals 



narrowly spatula-shaped shrubs 4. A. spicatum. 



Leaves 3-lobed at tip; flower-clusters drooping; petals reverse-egg-shaped; 



mostly trees ^...5. A. penns^lvanicum. 



Leaves divided into 3 to 5 leaflets; mostly trees; found in the Southwest 



6. A . negundo var. 



L Vine Maple (Acer circinatum Dougl.). — Usually widely spreading 

 shrubs or small trees with slender, often rechning stems sometimes taking root 

 where they touch the ground; bark smooth, grayish-brown, tinged with red; 

 leaves 7- or 9-lobed, 2 to 4^/2 inches across, smooth on both sides, or softly 

 hairy below when young, bright green, turning reddish-yellow or bright scarlet 

 in the Fall; flowers small, with dark purplish-red sepals and tiny white petals, 

 borne on slender stems in loose spreading clusters; fruits smooth, often red- 

 dish, with wings spreading opposite each other in a straight line; generally 



found as an understory shrub in ever- 

 green forests of the Northwest. 



Occurrence. — Olympic, abundant, from 

 lowest elevations to about 3,000 feet: Lake 

 Crescent; Elkhorn Guard Station, Elwha 

 River; Olympus Guard Station, Hoh River; 

 Duckabush River. MOUNT RAINIER, common, 

 1,700 to 4,500 feet: Longmire-Paradise road; 

 Ramparts Ridge trail; Sunset Park road. 



2. BiGTOOTH Maple (Acer grandi- 

 dentatum Nutt.), fig. 9L — Usually a 

 shrub 6 to 15 feet high, or sometimes a 

 small tree up to 40 or 50 feet high with 

 light brown twigs and gray branches; 

 leaves 2 to 5 inches across, roundish in 

 outline, dark green above, pale and more 

 or less hairy below, deeply divided into 

 3 lobes, the notches rounded between, 

 the lobes coarsely few-toothed; flowers 

 borne in spreading clusters, the flower- 

 stems softly hairy; fruits smooth, the 

 wings more or less parallel. The foliage 



Fig. 91. Bigtooth maple (Acer 

 grandidentalum) . 



