24 



YOSEMITE NATURE NOTES 



large leaves, which may occasionally 

 be more than twelve inches across, 

 ore especially noteworthy. They are 

 borne opposite on the branches, are 

 smooth and shiny green above, pale 

 green below, and palmately divided 

 into five broad lobes. 



Although the foliage of some of the 

 eastern maples assume vivid hues 

 before dropping from the tree in the 

 fall, such is not the case with this 

 western species. In autumn the color 

 of its foliage is not particularly at- 

 tractive, being generally character- 

 ized by dull brownish to yellow 

 shades. However, this maple has 

 other interesting features, not the least 

 of which are the large, pendent clus- 

 ters (racemes) of fragrant yellow flow- 

 ers which enliven the appearance of 

 the tree during the early spring when 



the leaves are unfolding. These clus- 

 ters, which include both staminate 

 (male) and pistillate (female) flowers, 

 are from four to six inches long. In- 

 sects, which are attracted in great 

 numbers to these flowers, serve to 

 pollinate the blossoms. The charac- 

 teristic fruit — a pair of nut-like seeds, 

 each attached to a large blade-like 

 wing — is fully developed by luly. At 

 that time they are about one to two 

 inches long. Their green color, typical 

 of midsummer, changes to a light 

 brown in the early fall. 



The bigleaf maple can be recog- 

 nized in winter by the stout twigs with 

 their opposite leaf scars. The leaf 

 SCOTS ore rather large, V-shaped or U- 

 shaped in outline, upon which are 

 from five to nine vascular bundle 

 scars. 



ROCKY MOUNTAIN MAPLE 

 Acer glabrum Torr. — Maple Family (Aceraceae) 



Although this species will be most 

 generally noted as a tall shrub, the 

 Rocky Mountain or dwarf maple oc- 

 casionally attains the stature of a 

 small tree, reaching a height of ten 

 to fifteen feet and a diameter of three 

 to four inches. It generally occurs in 

 moist but poor gravelly to rocky soils 

 in protected canyons and gulches up 

 to about the 7,000 foot elevation. Hik- 

 ers using the Ledge Trail will find it 

 common in such situations along that 

 route. 



The leaves, borne opposite on the 

 branches, have slender stems one to 

 five inches long, are one to three in- 



ches across, rather conspicuously 

 veined, and are dork green and shiny 

 upon the upper surface (paler below). 

 They are three (occasionally five) 

 lobed, with the edges oi the lobes 

 coarsely toothed. The stems of the 

 leaves are occasionally red. 



The winged seeds, which are about 

 one inch in length, are borne in pairs. 

 Before maturity they are a bright 

 rose-red in color, changing to russet- 

 brown before they ripen in late sum- 

 mer or early fall. 



The trunk possesses smooth, red- 

 dish-brown bark with a slight gray 

 tint. Mature twigs are reddish-brown. 



