Part 4

A very helpful practice for the beginner is that of making keys based upon various characters. Practice keys of this kind will bring out the differences and likenesses of trees as will no other means, and characters which have hitherto escaped the eye will be prominently brought forward. Nor should the student take his characters from books, but rather should he go to the woods and get his knowledge first hand.

It is hardly necessary to state that the key is a valuable crutch while learning to walk, but once the leg is strong enough to bear the weight it should be discarded, lest it become a burden. A key has for its main object the guidance of the student through the preliminary steps leading to a more intimate knowledge of the trees. When once he knows a tree, instinctively, because of long acquaintance with it, just as he knows people, then the need for a key will have ceased.

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 years. PINUS, p. 4.

dd. Leaves in fascicles of 8-many, on short, lateral branchlets, 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. 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 1/2-1-1/4 inches long, sessile, aromatic; cones 2-4 inches long; bark of trunk with raised blisters containing resin. ABIES, p. 27.

ff. Leaves seldom over 1/2 inch long, short-petioled, not aromatic; cones about 3/4 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. Leaves alternate or clustered, never opposite nor whorled.

d. Margin of leaves entire or only slightly undulate.

e. Leaves heart-shaped or rounded; fruit a legume. CERCIS, p. 167.

ee. Leaves oval, ovate or obovate; fruit not a legume.

f. Branches armed with stout, straight spines; fruit large, orange-like. MACLURA, p. 133.

ff. Branches without spines; fruit small, not orange-like.

g. Fruit an acorn. QUERCUS, p. 96.

gg. Fruit a drupe or berry.

h. Twigs spicy-aromatic when bruised; leaves of many shapes on the same branch. SASSAFRAS, p. 139.

hh. Twigs not spicy-aromatic; leaves not of many shapes on the same branch.