Remarks.—The red maple is not abundant enough in Indiana to be of any economic importance. It grows rapidly and should replace the silver maple for shade tree planting since its branches are not broken off as easily by ice storms and it is more resistant to insect attack.
3a. Acer rubrum variety Drummóndii (Hooker and Arnott) Torrey and Gray. This variety of the red maple is a form found in the dense swamps of the lower Wabash Valley. It is distinguished from the type by its twigs which generally remain more or less hairy until maturity; by the under surface of the leaves remaining more or less tomentose during the summer, and by its larger fruit. This variety is known with certainty only from Little Cypress Swamp in Knox County about 12 miles southwest of Decker. Here it is a frequent to a common tree associated with cypress, swell-butt ash, button-bush, sweet gum, etc. All of the trees of this locality have 5-lobed leaves.
ACER RUBRUM Linnæus. Red Maple. (× 1/2.)
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.