412 BETULACEuE. (BIRCH FAMILY.) 



# * # Shrtbs, with brownish bark and rounded crenate-toothed leaves fertile catkin* 

 very short-pedunded. 



6. B. pumila, L. (Low BIRCH.) Erect or ascending ; leaves obovate or 

 roundish-elliptical, coarsely crenate-toothed, those of the summer branchlets 

 downy and nearly orbicular ; fruiting catkins cylindrical ; the scales more or less 

 unequally 3-lobed ; fruit broadly winged. (B. glandulosa, Michx.) Bogs K. 

 New England (rare), Penn., Ohio, Wisconsin, and northward. Shrub 2 -8 

 high, with smooth, or sometimes resinous-warty, branchlets ; the growing twigs 

 downy. Leaves thickish, 1 ; - 1' long, paler or whitish underneath. 



7. B. ii;\iil, L. (DWARF or ALPINE BIRCH.) Branches spreading or 

 procumbent ; leaves orbicular, deeply crenate, smooth, reticulated-veiny under- 

 neath ; fruiting catkins oblong ; the scales nearly equally 3-cleft ; fruit narrowly 

 winged. Alpine summits of the mountains of Maine, New Hampshire, and 

 N. New York, and high northward. Shrub 10' -24' high, with leaves about ' 

 wide : varying, in less frigid stations, with the larger leaves twice that size, and 

 the branchlets often conspicuously warty with resinous dots, when it is B. rotun 

 difolia, Spach, and B. Littelliana, Tuckerm. (Eu.) 



2. AJLNUS, Tourn. ALDER. 



Sterile catkins elongated and drooping, with 5 bractlets and 1 to 3 flowers 

 under each scale, each flower usually with a 4-parted calyx and 4 stamens : fila- 

 ments very short : anthers 2-celled. Fertile catkins ovoid or oblong ; the fleshy 

 scales each 2-flowered, with a calyx of 4 little scales adherent to the scales or 

 bracts of the catkin, which are thick and woody in fruit, all coherent below, and 

 persistent. Shrubs or small trees, with stalked leaf-buds furnished with a sin- 

 gle scale; the (often racemed or clustered) catkins of both sorts produced at 

 the close of summer, remaining entirely naked through the winter, and ex 

 panding in early spring. (The ancient Latin name.) 



1. ALNUS PROPER. Fruit wingless. 



1. A. incana, Willd. (SPECKLED or HOARY ALDER.) Leaves broadly 

 oval or ovate, rounded at the base, sharply serrate, often coarsely toothed, whitened 

 and mostly downy underneath ; stipules oblong-lanceolate ; fertile catkins oval ; 

 fruit orbicular. (A. glauca, Michx.) Shrub 8 -20 high, forming thickets 

 along streams ; the common Alder northward from New England to Wisconsin. 

 Var. GLAtrcA has the leaves pale, but when old quite smooth, beneath. (Eu.) 



2. A. serrulate,, Ait. (SMOOTH ALDER.) Leaves obovate, acute at the 

 base, sharply serrate with minute teeth, thickish, smooth and green both sides, a lit- 

 tle hairy on the veins beneath ; stipules oval ; fertile catkins ovoid-oblong ; fruit 

 ovate. Shrub 6 -12 high, in similar situations; the common Alder from 

 Southern New England to Wisconsin, Kentucky, and southward. 



2. ALNASTER, Spach. Fruit with a winged margin: sterile flowers with a 

 calyx of a single scale, much as in Birch. 



3. A. viridis, DC. (GREEN or MOUNTAIN ALDER.) Leaves round- 

 oval or ovate, sometimes heart-shaped, glutinous and smooth or softly downy 

 underneath, serrate with very sharp and closely set teeth, on young shoots often 



