Habitat and Range.—Low, damp ground on which, in New England at least, the sugar maple is rarely if ever seen, or upon moist, rocky slopes.
Apparently a common tree from Ottawa westward throughout Ontario.
The New England specimens, with the exception of those from the Champlain valley, appear to be dubious intermediates between the type and the variety.
Maine,—the Rangeley lake region; New Hampshire,—occasional near the Connecticut river; Vermont,—frequent in the western part in the Champlain valley, occasional in all other sections, especially in the vicinity of the Connecticut; Massachusetts,—occasional in the Connecticut river valley and westward, doubtfully reported from eastern sections; Rhode Island,—doubtful, resting on the authority of Colonel Olney's list; Connecticut,—doubtfully reported.
South along the Alleghanies to the Gulf states; west to the 95th meridian.
The extreme forms of nigrum show well-marked varietal differences; but there are few, if any, constant characters. Further research in the field is necessary to determine the status of these interesting plants.
Habit.—The black maple is somewhat smaller than the sugar maple, the bark is darker and the foliage more sombre. It generally has a symmetrical outline, which it retains to old age.
Leaves.—The fully grown leaves are often larger than those of the type, darker green above, edges sometimes drooping, width equal to or exceeding the length, 5-lobed, margin blunt-toothed, wavy-toothed, or entire, the two lower lobes small, often reduced to a curve in the outline, broad at the base, which is usually heart-shaped; texture firm; the lengthening scales of the opening leaves, the young shoots, the petioles, and the leaves themselves are covered with a downy to a densely woolly pubescence. As the parts mature, the woolliness usually disappears, except along the midrib and principal veins, which become almost glabrous.
Horticultural Value.—Hardy throughout New England, preferring a moist, fertile, gravelly loam; young trees are rather more vigorous than those of the sugar maple, and easily transplanted. Difficult to secure, for it is seldom offered for sale or recognized by nurseries, although occasionally found mixed with the sugar maple in nursery rows.