SUMMER KEY TO THE GENERA* 
a. Leaves simple. 
b. Leaves needle-shaped, awl-shaped, strap-shaped or scale- 
like. 
c. Leaves in clusters of 2-many. 
d. Leaves in clusters of 2-5, sheathed, persistent for 
Several VeaTrs jadidsi ee ece et sane tae PINUS, p. 4. 
dd. Leaves in fascicles of 8-many, on short, lateral branch- 
lets, deciduous in autumn............. LARIX, p. 17. 
cc. Leaves solitary, not clustered. 
d. Leaves opposite. 
e. Twigs flattened; leaves all of one kind, scale-like, 
decurrent on the stem; fruit a small, pale brown 
CONE: sch ccnandas elke eeeaes dean tebe THUJA, p. 31. 
ee. Twigs essentially terete; leaves of two kinds, either 
scale-like, or else awl-shaped, often both kinds on 
the same branch, not decurrent on the stem; fruit 
berry-like, bluish ............. JUNIPERUS, p. 33. 
dd. Leaves alternate or spirally-whorled. 
e. Leaves flattened, soft to the touch. 
f. Leaves 14-114 inches long, sessile, aromatic; cones 
2-4 inches long; bark of trunk with raised blisters 
containing resin................50. ABIES, p. 27. 
ff. Leaves seldom over % inch long, short-petioled 
not aromatic; cones about 34 inch long; bark of 
trunk without raised blisters...... TSUGA, p. 29. 
ee. Leaves 4-sided, harsh to the touch.... PICEA, p. 18. 
bb. Leaves broad and flat. 
c. Leavesalternate or clustered,never opposite nor whorled. 
d. Margin of leaves entire or only slightly undulate. 
* See page xviii. 
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