638 



TREES OF NORTH AMERICA 



Distribution. Banks of mountain streams usually at elevations of 5000-6000 

 above the sea; rare and local; valley of the Columbia River in northern Montana, 

 Wasatch Mountains of Utah, mountains of southern Arizona and New Mexico and 

 of western Texas, and in Coahuila. 



** Flowers appearing before the leaves ; fruit ripening in the spring or early summer. 



11. Acer sacchariiium, L. Silver Maple. Soft Maple. 



Leaves truncate or somewhat heart-shaped at the base, deeply 5-lobed by narrow 

 sinuses, with acute irregularly and remotely dentate lobes, the middle lobe often 

 3-lobed, 6'-7' long, nearly as broad, membranaceous, bright pale green above, silvery 

 white and at first slightly hairy below, especially in the axils of the primary veins, 

 turning pale yellow in the autumn before falling; their petioles slender, drooping, 

 bright red, 4'-5' long. Flowers greenish yellow, opening during the first warm days 

 of the late winter or early spring long before the appearance of the leaves, on very 

 short pedicels, in sessile axillary fascicles on shoots of the previous year, or on short 



spur-like branchlets developed the year before from wood of the preceding season, 

 the staminate and pistillate in separate clusters, sometimes on the same and some- 

 times on different trees, and produced from clustered obtuse buds covered with thick 

 ovate pubescent red and green scales ciliate on the margins, with a thick fringe of 

 long rufous hairs; calyx slightly 5-lobed, more or less pubescent on the outer sur- 

 face, long and narrow in the staminate and short and broad in the pistillate flower; 

 corolla 0; stamens 3-7, with slender filaments, three times as long as the calyx of the 

 staminate flower and about as long as the calyx of the pistillate flower; ovary covered, 

 like the young fruit, with a thick coat of pubescence, rudimentary in the sterile 

 flower; styles united at the base only, with long exserted stigmatic lobes. Fruit 

 ripening in April and May before the appearance of the leaves, on slender drooping 

 pedicels, l'-2' long, glabrous, 1^' to nearly 3' long, with thin almost straight conspic- 

 uously falcate divergent wings sometimes |' broad, prominently reticulate-veined 

 and pale chestnut-brown; seeds \' long, with a pale reddish brown wrinkled coat, 

 germinating as soon as they fall to the ground, and producing plants with several 

 pairs of leaves before the end of the summer. 



A tree, 90-120 high, with a trunk 3-4 in diameter, generally dividing 10-15 



