10 
41 Thorns commonly formed by the pointed ends of branches. 
Fruit with a single seed inclosed in a hard stone—Plum, 103 
42 Side veins nearly straight, usually unbranched—43 
42 Side veins curving or prominently forking—52 
43 Leaf base unsym metrical and margins doubly toothed. 
Fruit Hat, with a broad wing surrounding the single 
seed—Elm, 137 
43 Leaf base symmetrical or nearly so—44 
44 Margins with coarse teeth or angles, less than 6 per inch—45 
44 Margins with small teeth, more than 6 per inch—47 
45 Fruit a nut; one to several nuts completely inclosed in a 
prickly bur until mature. Each side vein of the leaf 
blade terminating in a marginal tooth—40 
45 Fruit a nut with its base set in a scaly cup. Leaf margins 
commonly with a few large angular teetn or shallow an¬ 
gular lobes, each tipped with a short bristle—Oak, 123 
40 Nut triangular in section. Bark of trunk smooth, firm, and 
light gray—Beech, 119 
40 Nut not triangular in section. Bark of older trunks fur¬ 
rowed—Chestnut, 122 
47 Bark chalky white, or whitish—Birch, 108 
47 Bark not chalky white, nor whitish—48 
48 Small twigs aromatic when bruised—Birch, 108 
48 Small twigs not aromatic when bruised—49 
49 Leaves taper-pointed—50 
4 ( .) Leaves not taper-poi nted—51 
50 Bark of trunk brownish, with somewhat shredded Hakes or 
scales—Hop Hornbeam, Ironwood, Leverwood, Hornbeam, 
Hardhack, Ortrua virginiana (Mill.) K. Koch. 
50 Bark of trunk close and gray, with no tendency to become 
furrowed or scaly—American Hornbeam, Blue Beech, Water 
Beech, Hornbeam, Ironwood, Carpinus carolimana Walt. 
51 Leaves with base broadly wedge-shaped, or abrupt, and 
entire. Pointed at apex. Twigs reddish. Bark of old 
trunks red or brown, forming scales with upturned papery 
margins—Birch, 109 
