160 



American Midland Naturalist Monograph No. 4 



SEN. YOSEMITE, occasional, 5,000 to 10,000 feet: trails leading out of Yosemite Valley; 

 Glacier Point; Clark's Point. KINGS CANYON: Junction Meadows. SEQUOIA, 6,000 

 feet: Alwell Mill; Wiiitney Creek; near Mineral King; near Wolverton Creek. GLA- 

 CIER, abundant, 3,100 to 7,800 feet: Lake McDonald Hotel; Avalanche campgrounds; 

 Going-to-the-Sun Chalet; Swiftcurrent Lake and valley; Iceberg Lake trail; Crossley 

 Lake. YELLOWSTONE: Mammoth Hot Springs; mouth of Lost Creek; near east entrance. 

 GRAND TETON, occasional, 6,700 to 8,000 feet: Granite Canyon. ROCKY MOUNTAIN, 

 8,000 to 9,000 feet. MESA VERDE, rare: west of Prater Canyon ranch house, 7,500 feet. 

 BKYCE CANYON. ZION : moist places on the plateau, about 6,000 feet. GRAND CANYON, 

 7,000 to 8,000 feet. North Rim, occasional just below rim: near top of Kaibab trail; 

 McKmnon Point. South Rim, rare. Canyon, occasional on the north side of the river: 

 Kaibab trail below North Rim. 



4. Mountain Maple (Acer spicatum Lam.), fig. 93. — Shrub or small 

 tree up to about 25 feet high; leaves mostly 3-lobed, sometimes slightly 5- 



lobed, 21/2 to 5 inches long, 

 smooth above, hairy below, 

 light green, turning orange or 

 scarlet in the Fall; flowers 

 greenish-yellow, borne in nar- 

 row erect spikes 3 to 5^^ inches 

 long; fruits at first hairy, be- 

 coming smooth at maturity, 

 wings spreading at an acute or 

 nearly right angle, sometimes 

 bright red. 



OccuTTence. — ISLE BOYALE, 

 common: near Lake Desor; Mott 

 Island at northeast tip of isiand. 



5. Striped Maple {Acer 

 pennsylvanicum L.). — Usually 

 a small tree up to 30 or 35 

 feet high, with smooth green 

 branchlets becoming striped 

 with white lines; leaves 3-lobed 

 near tips, 5 to 7 inches long, 

 bright green, rusty-hairy below 

 when young, turning yellow in 



the Fall; flowers small, yellow, borne in slender elongate pendulous clusters 



4 to 6 inches long; wings of fruits widely spreading. 

 Occurrence. — ISLE ROYALE, rare. 



6. Inland Boxelder (Acer negundo L. var. interius (Britt.) Sarg.). — 

 Usually a tree 20 to 50 feet high, or sometimes a tall spreading shrub; bark 

 grayish-brown, rough in age; leaves divided into 3 or sometimes 5 leaflets; 

 leaflets oblong, pointed at the tips, 2 to 5 inches long, the margins irregularly 

 toothed; flowers yellowish-green, appearing before the leaves; wings of fruits 

 spreading obliquely. 



Occurrence. — MESA VERDE: west of ranch house in Prater Canyon, 7,500 feet. 



Fig. 93. Mountain maple (Acer spicatum). 



