WINTER KEY TO THE GENERAB
Reading edition
WINTER KEY TO THE GENERAB
a. Leaves persistent and green throughout the winter, needle-shaped, awl-shaped or scale-like.
b. Leaves in clusters of 2-5, sheathed. PINUS, p. 5.
bb. Leaves solitary, not clustered.
c. Leaves opposite.
d. Twigs flattened; leaves all of one kind, scale-like, decurrent on the stem; fruit a small, pale brown cone. THUJA, p. 31.
dd. 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.
cc. Leaves alternate or spirally-whorled.
d. Leaves flattened, soft to the touch.
e. 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.
ee. 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.
dd. Leaves 4-sided, harsh to the touch.PICEA, p. 19.
aa. Leaves not persistent and green throughout the winter, but deciduous in early autumn.
b. Twigs, branches or trunks armed with stiff, sharp prickles, spines or thorns.
c. Thorns or spines not exceeding 1/2 inch in length on the branches.
d. Spines in pairs at each node; buds rusty-hairy, 3-4 superposed; fruit a flat pod.ROBINIA, p. 169.
dd. Spines one at each node; buds glabrous, not superposed; fruit orange-like. MACLURA, p. 133.
cc. Thorns or spines much exceeding 1/2 inch in length on the branches.
d. Thorns usually branched, situated above the nodes; lateral buds superposed, the lower covered by bark; fruit a flat pod.GLEDITSIA, p. 165.
dd. Thorns unbranched on twigs, situated at the nodes; lateral buds not superposed, not covered by bark; fruit a small pome.CRATAEGUS, p. 151.
bb. Twigs, branches or trunks unarmed.
c. Leaf-scars mainly crowded on short, stout, lateral shoots.
d. Bundle-scar 1; fruit a cone, usually present. LARIX, p. 17.
dd. Bundle-scars 2; fruit a globose drupe falling in autumn.GINKGO, p. 3.
cc. Leaf-scars distributed along the lateral branches.
d. Leaf-scars (or some of them) 3 at a node, i. e., whorled.CATALPA, p. 223.
dd. Leaf-scars 1-2 at a node, i.e., not whorled.
e. Leaf-scars 2 at a node, i.e., opposite.
f. Terminal buds 1/2 - 1-1/2 inches long, resin-coated; twigs very stout.AESCULUS, p. 195.
ff. Terminal buds rarely exceeding 1/2 inch in length, not resin-coated; twigs not conspicuously stout.
g. Leaf buds with 1 pair of scales visible.
h. Buds scurfy-pubescent.VIBURNUM, p. 229.
hh. Buds glabrous.CORNUS, p. 203.
gg. Leaf buds with 2 or more pairs of scales visible.
h. Bundle-scars usually 3, distinct, separated. ACER, p. 174.
hh. Bundle-scars many, minute, more or less confluent in a U-shaped line.FRAXINUS, p. 211.
ee. Leaf-scars 1 at a node, i.e., alternate.
f. Bundle-scars 1-3.
g. Bundle-scar only 1, or appearing as 1.
h. Twigs bright green, spicy-aromatic; bundle-scar appearing as a horizontal line; terminal bud present; pith homogeneous.SASSAFRAS, p. 139.
hh. Twigs brownish, not spicy-aromatic; bundle-scar appearing as a large dot; terminal bud absent; pith chambered.CELTIS, p. 131.
gg. Bundle-scars 3 or in 3 compound, but distinct groups.
h. Terminal bud present.
i. Stipule-scars present.
j. First scale of lateral bud directly in front, i.e., exactly above the center of the leaf-scar; twigs brittle; pith somewhat star-shaped in cross-section.POPULUS, p. 45.
jj. First scale of lateral bud not directly in front, i. e., to one side of the center of the leaf-scar; twigs not brittle; pith circular in cross-section.PRUNUS, p. 153.
ii. Stipule-scars absent.
j. Buds bright to dark red, the terminal 1/8 - 1/4 inch long.
k. Branches contorted, bearing many short, spur-like branchlets; fruit an apple an inch or more in diameter, light green.PYRUS, p. 143.
kk. Branches not contorted, not bearing short, spur-like branchlets; fruit berry-like, 1/2 inch long, blue-black.NYSSA, p. 209.
jj. Buds brownish to gray, the terminal exceeding 1/4 inch in length.
k. Buds narrow-conical, sharp-pointed; leaf-scars small, narrowly crescent-shaped; twigs about 1/16 inch thick; pith homogeneous; fruit berry-like, not present.AMELANCHIER, p. 149.
kk. Buds broadly conical to ovoid, blunt-pointed; leaf-scars conspicuous, broadly heart-shaped; twigs about 1/4 inch thick; pith chambered; fruit a nut, often present.JUGLANS, p. 61.
hh. Terminal bud absent (sometimes present on short shoots of Betula).
i. Stipule-scars present.
j. Bud-scale only 1 visible; twigs brittle. SALIX, p. 34.
jj. Bud-scales 2 or more; twigs not brittle.
k. Bark smooth, close, warty or peeling into papery layers, but not flaky nor rough-ridged.
l. Tip of bud appressed; fruit berry-like. CELTIS, p. 131.
ll. Tip of bud not appressed; fruit not berry-like.
m. Trunk fluted; catkins not present in winter; lenticels not elongated horizontally; low tree or bushy shrub.CARPINUS, p. 83.
mm. Trunk not fluted; catkins usually present in winter; lenticels elongated horizontally; large trees.BETULA, p. 85.
kk. Bark flaky or rough-ridged, not warty nor peeling off in papery layers.
l. Bundle-scars depressed, conspicuous; bark thick, more or less deeply furrowed.ULMUS, p. 123.
ll. Bundle-scars not depressed, inconspicuous; bark thin, broken into narrow, flattish strips, loose at the ends.OSTRYA, p. 81.
ii. Stipule-scars absent.
j. Buds silky-pubescent, depressed; twigs stout, clumsy, blunt, with conspicuous leaf-scars.GYMNOCLADUS, p. 163.
jj. Buds glabrous, not depressed; twigs slender, with inconspicuous leaf-scars.
k. Buds 1/8 inch long, obtuse, somewhat flattened and appressed; pith with reddish longitudinal streaks.CERCIS, p. 167.
kk. Buds 1/8-1/4 inch long, acute, not flattened nor appressed; pith without reddish streaks.PRUNUS, p. 153.
ff. Bundle-scars 4-many.
g. Bundle-scars in a single U-shaped line.
h. Terminal bud present; fruit berry-like; a shrub or small tree.PYRUS, p. 143.
hh. Terminal bud absent; fruit not berry-like; large trees.
i. Stipule-scars present; twigs slender.
j. Stipule-scars encircling the twig; leaf-scars nearly surrounding the bud; bark peeling off in thin plates, exposing the lighter colored inner bark.PLATANUS, p. 141.
jj. Stipule-scars not encircling the twig; leaf-scars not nearly surrounding the bud; bark thick, rough-ridged, not exposing the inner bark.ULMUS, p. 123.
ii. Stipule-scars absent; twigs very stout.
j. Bundle-scars usually not more than 5. GYMNOCLADUS, p. 163.
jj. Bundle-scars usually 6-12. AILANTHUS, p. 171.
gg. Bundle-scars variously grouped or scattered, but not in a single line.
h. Terminal bud present.
i. Stipule-scars present.
j. Stipule-scars encircling the twig; visible bud-scales 2, united.LIRIODENDRON, p. 137.
jj. Stipule-scars not encircling the twig; visible bud-scales more than 2, not united.
k. Buds 4 times as long as broad, not clustered at the tips of vigorous shoots; fruit a prickly bur.FAGUS, p. 93.
kk. Buds not 4 times as long as broad, usually clustered at the tips of vigorous shoots; fruit an acorn.QUERCUS, p. 98.
ii. Stipule-scars absent.CARYA, p. 67.
h. Terminal bud absent (occasionally present in Castanea).
i. Bud at end of twig very obliquely unsymmetrical, mucilaginous when chewed.TILIA, p. 201.
ii. Bud at end of twig symmetrical, not mucilaginous when chewed.
j. Bud-scales 2-3 visible; pith star-shaped in cross-section; sap not milky; fruit a prickly bur, present; large tree. CASTANEA, p. 95.
jj. Bud-scales 4-8 visible; pith not star-shaped in cross-section; sap milky; fruit berry-like, not present; small tree.MORUS, p. 135.