Oaks
Botanists and dendrologists
consider oaks in two major groups: the white oaks and the red or black
oaks. The major distinction between the two is most obvious in the
leaves. Many kinds of tree leaves, including many oaks, have deeply
wavy edges. The inset or coved-in part is called the sinus, and the
projecting part is called the lobe. White oak leaves have rounded
lobes and red or black oaks have predominantly pointed, or so-called
bristle-tipped, lobes.
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Fig. 11 White Oak
Fig. 12 Red Oak |
White oak and red oak acorns
have different characteristics, too. Some differences are visible and
some are more physiological. One feature that’s visually
distinguishable is that the white oak acorns’ cups tend to be warty,
whereas those of the red oak group tend to be scalier. The main
physiological difference is that white oak acorns mature in one season
and are ready to sprout when they fall. Although this physiological
difference is not as obvious as the leaf differences, there are
instances of white oaks having a heavy fall seed crop and an abundance
of new seedlings, with acorns still attached, sprouting under a parent
tree.
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Fig. 13 Black Oak twig
with buds
Fig. 14 Black Oak twig
with leaves and acorns |
The black oak, as well as the
northern red oak, serves well to represent the red oak group. These
oaks have the characteristic clustered buds at the twig tips, a
feature that typifies oaks in general. The buds tend to be conical in
shape and are, of course, alternate on the twig as are the lower pair
of leaves in the red oak illustration. (Because the buds and leaves
are more crowded at the twig tip, the alternate pattern can be
obscured but it is definitely still there.)
Beech
The American beech is a
smooth-barked tree with simple, elliptical leaves. The side veins
coming off of the leaf’s central vein extend out to the leaf margin
and end in a tooth or small bristle tip.
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Fig. 15 American Beech twig
with fruit and seeds |
Note that the American Beach
tree is afflicted with a condition called beech bark disease. The
disease is caused by a fungus and results in disfigurement of the bark
to the point of, in severe cases, rough bark that may look more like
that of an oak than a beech.
