512 BETULACEAE. 
1. Alnus Alnobétula (Ehrh.) K. Koch. Green or Mountain Alder. (Fig.1220.) 
Bethla Alnobetula Ehth. Beitr. 2:72. 1788. 
Betula viridis Chaix; Vill. Hist. Pl Sati 3: 789. 1789. 
Alnus viridis DC. Fl. Fr. 3: 304. 1805. 
Alnus Alnobetula K. Koch, Dendr, 2: Part 1, 625. 1872. 
A shrub, 2°-10° high, the young foliage glutinous 
and more or less pubescent. Jeaves oval or ovate, 
obtuse or acute, sharply and more or less irregularly 
serrulate or incised-serrulate, when mature dark 
green and glabrous above, light-green and usually 
pubescent on the veins beneath, 2’-5’ long, 1%4/—3/ | 
wide; petioles 4//-12’/ long; aments expanding with 
the leaves, the staminate slender, naked, 114/-214” 
long, the pistillate from scaly buds, oblong or ovoid- 
oblong,slender-peduncled, becoming 6’’-8’’ long and 
4//-5’’ in diameter in fruit, their bracts irregularly 5- 
toothed; nut oblong, the thin wings about as broad 
as the body. 
Newfoundland to Alaska, Massachusetts, New York, 
Michigan and British Columbia, and in the higher Alle- 
ghanies of Virginia and North Carolina. Alsoin Europe 
and Asia. June. 
25 Alnus incana (L. ) Willd. Speckled or Hoary Alder. (Fig. 1221.) 
Betula Alnus var. tncana I,. Sp. Pl. Ed. 2, 1394. 1763. 
Alnus incana Willd. Sp. Pl. 4: 335. 1805. 
A shrub, or rarely a small tree, 8°-25° high, the 
twigs glabrous, the young shoots pubescent. Leaves 
oval or ovate, acute or sometimes obtuse at the apex, 
finely serrulate or dentate, with the teeth serrulate, 
obtuse or some of them acute at the base, dark green 
above, pale or glaucous and pubescent, at least on 
the veins beneath, 2/5’ long, 114’-4’ wide, the veins 
prominent on the lower surface; stipules oblong- 
lanceolate, deciduous; petioles 4’’-12’/ long; aments 
appearing from naked buds, unfolding much before 
the leaves, the staminate 1 's/—3/ long, the pistillate 
ovoid, about 1%’ long and 3/’-5’’ in diameter in fruit, 
their bracts 5-toothed; nut orbicular, coriaceous- 
margined, 
In wet soil, Newfoundland to the Northwest Terri- 
tory, south to southern New York, Pennsylvania and 
Nebraska. Also in Europe and Asia. Wood soft, light 
brown; weight per cubic foot 28 lbs. April-May. ~ 
Te Alnus rugosa Oe K. Koch. Smooth Alder. (Fig. 1222.) 
Betula Alnus rugosa DuRoi, Harbk. I: 112. 1771. 
Alnus serrulata Willd. Sp. Pl, 4: 336. 1805. 
Alnus rugosa K. Koch, Dendr. 2: Part 1, 635. 1872. 
A shrub 5°—20° tall, or sometimes a small tree, 
attaining a maximum height of 4o° and a trunk 
diameter of 6’, the bark smooth, the younger 
shoots somewhat pubescent. Leaves green on 
both sides, obovate or oval, mostly obtuse and 
rounded at the apex, narrowed or rounded at the 
base, sharply and minutely serrulate, when mature 
glabrous above, usually pubescent on the veins be- 
neath, 3/—5’ long, stipules oval, deciduous; petioles 
4//-12’’ long; aments appearing from naked buds, 
unfolding much before the leaves (or in the South 
after the leaves), the staminate 2’—4’ long, the pis- 
tillate ovoid, 6’’-9’’ long in fruit; nut ovate, nar- 
rowly coriaceous-margined. 
In wet soil, or on hillsides, Maine to Ohio ahi Min- 
nesota, Florida and Texas. Wood soft, light brown; 
weight per cubic foot 29 lbs. March-April. 
