Smooth Alder 



261 



The thin bark is gray and nearly smooth outside, red within. The young 

 twigs are slender, glandular, and minutely hairy, becoming brown and shining. 

 The leaves are ovate, rather thin, 6 to 10 cm. long, short-pointed or bluntish, finely 

 and somewhat irregularly toothed but not lobed, bright green, smooth, and with 

 impressed veins on the upper side, paler green and hairy in the axils of the 

 prominent veins beneath ; the leaf-stalks are i to 2 cm. long. The oblong fruit- 

 ing catkins are about 1.5 cm. long. The nut is about 2 mm. long, bordered on 

 each side by a thin wing about i mm. wide. 



Alnus sinuata (Regel) Rydberg, a shrub of the northern Rocky Mountains 

 and the Northwest, has sinuately lobed or incised leaves, which are also more 

 coarsely toothed; it may sometimes form a tree. 



2. SMOOTH ALDER — Alnus serrulata Willdenow 

 Betula Alnus rugosa Du Roi. Alnus rugosa K. Koch 



Usually a shrub not over 6 meters high, forming thickets along water and on 

 moist hillsides, this alder in the South sometimes forms single trunks 13 meters 

 high and 1.5 dm. thick. It ranges from Maine 

 to Florida, Minnesota, Arkansas, and Texas. 

 Trees 8 meters high have been observed on 

 Staten island, New York. 



The thin bark is smooth or nearly so, and 

 dark brown. The young twigs are more or less 

 hairy, but soon become smooth and brown. 

 The buds are about 5 mm. long. The leaves 

 arc prevaiUngly obovate, but sometimes oval, 

 blunt or rounded at the apex, usually nar- 

 rowed, though sometimes rounded at the base, 

 sharply and finely toothed, 7 to 13 cm. long 

 and rather thin; when mature they are smooth 

 and dark green on the upper surface, a Uttle 

 lighter green beneath and usually hairy along 

 the veins; the leaf-stalks are i to 2.5 cm. in 

 length, and the oval stipules fall away early. The staminate catkins unfold in early 

 spring, before the leaves at the north, with or after the leaves in the south, and 

 are 5 to 10 cm. in length. The ripe pistillate catkins are 1.5 to 2 cm. long; the 

 nut is ovate and sharply margined but not winged. 



The wood is soft, close-grained, and hght brown; its specific gravity is about 

 0.47. It is used as fuel and for charcoal. The leaves are glutinous when young. 



Fig. 219. — Smooth Alder. 



