TREES OF NORTH AMERICA 



venulose, the veinlets more conspicuous on the lower surface, I'-lj' long, f'-l^' wide; 

 petioles slender, glabrous '-$' in length; stipules scarious, ovate-oblong, rounded at apex. 

 Flowers: staminate aments usually solitary or in pairs, sessile, l'-l|' long, ' thick, with 

 broadly ovate pubescent dark red scales acute and apiculate at apex; pistillate aments 

 \' long, about T V thick, with acute light green scales. Fruit: strobiles pendulous on 

 peduncles \'-\' long, cylindric, f ' in length, about ' thick, their scales glabrous longer 

 than broad, the lobes narrowed at the rounded apex, ciliate, the lateral slightly spread- 

 ing, one third shorter than the terminal lobe. 



A tree 18-20 high, with a trunk rarely more than 6' in diameter, and slender red gla- 

 brous branchlets thickly covered with circular white glands. Bark close, chestnut-brown, 

 marked by conspicuous horizontal white lenticels, about \' thick. 



Distribution. Swamps near Dawson, Yukon Territory, forming jungles with Betula 

 glandulosa Michx., B. alaskana Sarg., and various Willows: as a large shrub in Jasper 

 Park near Jasper, Alberta. 



4. ALNUS L. Alder. 



Trees and shrubs, with astringent scaly bark, soft straight-grained wood, naked stipitate 

 winter-buds formed in summer and nearly inclosed by the united stipules of the first leaf, 

 becoming thick, resinous, and dark red. Leaves open and convex in the bud, falling 

 without change of color; stipules of all but the first leaf ovate, acute, and scarious. Flowers 

 vernal, or rarely opening in the autumn from aments of the year, in 1-3-flowered cymes, 

 in the axils of the peltate short-stalked scales of stalked aments formed in summer or 

 autumn in the axils of the last leaves of the year or of those of minute leafy bracts; stamin- 

 ate aments elongated, pendulous, paniculate, naked and erect during the winter, each 

 staminate flower subtended by 3-5 minute bractlets adnate to the scales of the ament, and 

 composed of a 4-parted calyx, and 1-3 or usually 4 stamens inserted on the base of the calyx 

 opposite its lobes, with short simple filaments; pistillate aments ovoid or oblong, erect, 

 stalked, produced in summer in the axils of the leaves of a branch developed from the 

 axils of an upper leaf of the year, and below the staminate inflorescence, inclosed at first 

 in the stipules of the first leaf, emerging in the autumn and naked during the winter, or 

 remaining covered until early spring; pistillate flowers in pairs, each flower subtended by 

 2-4 minute bractlets adnate to the fleshy scale of the ament becoming at maturity thick 

 and woody, obovate, 3-5-lobed or truncate at the thickened apex, forming an ovoid or 

 subglobose strobile persistent after the opening of its closely imbricate'd scales; calyx 0; 

 ovary compressed; nut minute, bright chestnut-brown, ovoid to oblong, flat, bearing at 

 the apex the remnants of the style, marked at the base by a pale scar, the outer coat of 

 the shell produced into lateral wings often reduced to a narrow membranaceous border. 



Alnus inhabits swamps, river bottom-lands, and high mountains, and is widely and gen- 

 erally distributed through the northern hemisphere, often forming the most conspicuous 

 feature of vegetation on mountain slopes, ranging at high altitudes southward in the New 

 World through Central America to Colombia, Peru, and Bolivia, and to upper Assam and 

 Japan in the Old World. Of the eighteen or twenty species now recognized nine are North 

 American; of these, six attain the size and habit of trees. Of the exotic species, Alnus 

 vulgaris Hill., a common European, north African, and Asiatic timber-tree, was introduced 

 many years ago into the northeastern states, where it has become locally naturalized. 

 The wood of Alnus is very durable in water, and the astringent bark and strobiles are used 

 in tanning leather and in medicine. 



Alnus is the classical name of the Alder. 



CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT SPECIES. 



Flowers opening in spring with or after the leaves; stamens 4; pistillate aments inclosed 

 during the winter; wing of the nut broad; leaves ovate, sinuately lobed, lustrous on the 

 lower surface. 1. A. sinuata (B, F, G). 



