=5. Acer sáccharum= Marshall. Sugar Maple. Sugar Tree. Hard Maple. Rock
Maple. Plate 115. Usually large, tall trees. The bark of small trees is
smooth or rough, becoming fissured on old trees, tight or on very old
trees sometimes the ridges loosen on one edge and turn outward. The
leaves are extremely variable on different trees, and frequently show a
wide variation on the same tree, as to form and in the presence or
absence of hairs on the petioles and on the under surface of the leaves.
In our area all of the forms which have the majority of the leaves
longer than wide or about as wide as long, may be considered as falling
within the type. The average sized leaves are 6-12 cm. long, 3-5 lobed,
more or less cordate at the base, generally with a broad sinus,
sometimes truncate or slightly wedge-shape, sinuses generally
wide-angled and rounded at the base, sometimes acute, hairy beneath when
young, becoming smooth at maturity except for a few hairs along the
veins or in the main axils of the veins, or sometimes remaining more or
less pubescent over the whole under surface, more or less glaucous
beneath; flowers appear in April or May, on hairy pedicels 3-7 cm. long,
the staminate and pistillate in clusters on the same or different trees;
fruit ripening in autumn, samaras glabrous and usually 2-4 cm. long.
=Distribution.=--Newfoundland to Georgia, west to Manitoba and south to
Texas. A frequent to a very common tree in all parts of Indiana. It is
confined to rich uplands, or along streams in well drained alluvial
soil. Throughout our area it is constantly associated with the beech. It
is absent in the "flats" of the southeastern part of the State, and on
the crest of the ridges of the "knob" area of Indiana, but it is a
frequent or common tree on the lower slopes of the spurs of the "knobs."
=Remarks.=--The under surface of the leaves of the sugar maple in the
northern part of its range are green, while those of the southern part
of its range are quite glaucous beneath. To distinguish these two
intergrading forms the southern form has been called =Acer saccharum=
var. =glaucum= Sargent[61]. All of the trees seen in Indiana have leaves
more or less glaucous beneath. This character, however, is not always
evident in dried specimens. The writer prefers not to apply the varietal
name to the forms of our area. The sugar maple always has been and will
continue to be one of the most important trees of the State. In its mass
distribution in Indiana it ranks not less than third. In the quality and
uses of its wood it is equalled or exceeded only by the oak, ash and
hickory. When compared with white oak it is a little lighter but thirty
per cent stronger and fifty-three per cent stiffer. The greatest amount
of the annual cut of maple is worked into flooring which is shipped to
all parts of the world. It is much used in the manufacture of furniture
and ranks third in use for veneer and hard wood distillation, and as a
fuel wood is excelled only by hickory. Since pioneer times, the sap of
this tree has been made into sirup and sugar and their manufacture now
forms a valuable industry. On an average it takes 3 to 4 gallons of sap
to make a pound of sugar, and an average sized tree will annually yield
about 3 to 4 pounds of sugar.
[Illustration: Plate 115.