A specimen collected in the "bottoms" about two miles east of
Huntingburg in Dubois County has 3-lobed leaves which are tomentose
beneath at fruiting time and has fruit intermediate in size between the
type and variety _Drummondii_ which I doubtfully refer to variety
tridens Wood.
=4. Acer nìgrum= F. A. Michaux. Black Maple. Black Sugar. Plate 114.
Medium to large sized trees with dark furrowed bark on old trees; leaves
a little wider than long, 6-15 cm. long, on petioles usually 3-15 cm.
long which are more or less swollen at the base and by maturity develop
a scale like appendage on each side of the petiole at the
base--especially on each of the terminal pair of leaves, sometimes with
foliar stipules which are 2-3 cm. long on stalks of equal length, leaves
with three main lobes, the two lower lobes generally have a small lobe
at their base, margins of lobes entire and undulating, sinuses between
main lobes generally rounded at the base, wide and shallow, base with a
narrow sinus, the lower lobes often overlapping, rarely somewhat
dentate, dark green above and a paler yellow green below, hairy on both
surfaces when young, becoming at maturity glabrous above and remaining
more or less pubescent beneath; flowers appear in May when the leaves
are about half grown on long hairy pedicels, the staminate and
pistillate in separate clusters on the same or different trees; fruit
matures in autumn, the samaras about 3 cm. long.
=Distribution.=--Quebec to Georgia, west to South Dakota and south to
Louisiana. Found in all parts of Indiana and invariably associated with
sugar maple, and often with beech in addition. Frequently almost pure
stands of sugar maple may be found with the black maple absent. Where
found it is usually a frequent to common tree, and when it occurs on a
wooded slope it is more frequent near the base and appears to be able to
advance farther into moist situations than its congener.
=Remarks.=--This tree cannot be distinguished from the sugar maple by
its form, but at short range can be separated from it by its richer
green foliage and by the drooping habit of the lower lobes of the
leaves. It is commonly separated from the sugar maple by the darker
color and by the narrower and shallower furrows of the bark, but these
characters will not always separate the two species. Hence, when buying
black maple trees from a nurseryman you may receive the sugar maple.
Those who distinguish the two species agree that the black maple is the
more desirable tree for shade tree planting. The black and sugar maple
are the two most desirable trees for shade tree planting in Indiana.
They are long lived, have a very desirable form, beautiful foliage, a
long leaf period, and are quite free from disease and insect injury.
[Illustration: Plate 114.