5b. ssp. nigrum (F. Michx.) Desmarais (black maple)

A. saccharum var. nigrum (F. Michx.) Britton

A. saccharum var. viride (Schmidt) Voss

A. nigrum F. Michx.

A. nigrum f. pubescens Deam

A. nigrum var. palmeri Sarg.

Pl. 196 o; Map 808

Bark gray to dark gray or brown, somewhat roughened, becoming deeply furrowed and sometimes with peeling ridges on older trees. Leaf blades 6–15 cm long, the undersurface pale yellowish green to green and usually also hairy, the lobes tapered to sharply pointed tips, usually lacking or with very few secondary lobes or teeth, the sinuses between the main leaf lobes mostly forming angles of greater than 90°, the margins often slightly curled under. Calyx frequently hairy, but without dense white hairs on the inner surface that extend past the lobes. Flower stalks elongating to 5–10 cm, usually hairy. Ovary and young fruit glabrous. 2n=26. April–May.

Scattered in northern Missouri, uncommon south of the Missouri River (northeastern U.S. west to Minnesota and Arkansas; Canada). Mesic to dry upland forests, margins of glades, ledges and bases of bluffs, and banks of streams.

Trees with the typical “black maple” morphology are most common in northern Missouri, but they may also be found occasionally elsewhere in the state. In addition to the characters in the key to subspecies above, such trees also have the petioles abruptly enlarged at the base and often with small, leaflike, stipular outgrowths. The leaves are duller on the upper surface than those of ssp. saccharum and tend to be both less deeply divided and less toothed along the margins (although these differences are difficult to quantify). For further discussion, see the treatment of ssp. schneckii and ssp. saccharum.