1. Acer ginnala Maxim. (Amur maple, Siberian maple)
A. tataricum L. ssp. ginnala (Maxim.) Wesm.
monoecious, shrubs or small trees to 3(8) m tall with spreading branches, the bark
of young trees more or less roughened and gray, eventually becoming separated
into long thin plates on older trees. Twigs yellowish brown to brown, the
winter buds ovate, pointed at the tip, with 2 or 4 overlapping outer scales
usually obscuring 2 or more inner scales. Leaf blades 2–8 cm long,
broadly triangular-ovate in outline, the undersurface lighter green than the
green to bluish green upper surface, glabrous or hairy along the main veins,
usually with 3 main lobes (rarely with 2 additional short lobes), these tapered
to sharply pointed tips and with the sinuses angled or V-shaped, the lateral
lobes cut 1/3–1/2 of the way to the base, the central lobe often longer
than the lateral ones and broadest at or just above the base, the margins
irregularly toothed (sometimes appearing doubly toothed). Inflorescences
produced during or after expansion of the leaves; dense, narrow panicles from
branch tips; the flowers individually short-stalked. Calyces 1.8–2.5 mm
long, the sepals fused only at the very base, the 4 lobes oblong-elliptic,
rounded at the tips, whitish green, the margins scarious and usually with a
fringe of short, curly hairs. Petals 4, 1.5–2.0 mm long, narrowly
spatulate to oblanceolate, yellowish white. Staminate flowers with (7)8 stamens
inserted on the margin of a nectar disk. Pistillate flowers with the ovary
densely hairy. Fruits dispersing mostly long after the leaves are mature, the
samaras 2.0–3.5 cm long, glabrous or sparsely hairy, the wings
1.5–3.0 cm long, narrowly spreading, sometimes appearing parallel or
nearly so. 2n=26. April–June.
known thus far from only from Howell and Lincoln
Counties (native of eastern Asia;
naturalized sporadically in the northeastern U.S.
west to Minnesota).
Disturbed portions of mesic upland forests and old fields.
ginnala can be difficult to distinguish from glabrescent individuals of A.
rubrum. It may be distinguished by its more compact and usually shrubby
growth form, as well as its winter buds with usually fewer observable bud
scales. Amur maple was first reported for Missouri
by Ebinger and McClain (1991), who documented an extensive population near
Elsberry in fields and forests surrounding the Plant Materials
Center of the Natural
Resources Conservation Service. It is fairly widely cultivated in northeastern
North America and Europe, but it appears to
escape relatively uncommonly. In the autumn, the foliage turns a beautiful
bright crimson color. A number of cultivars (mostly differing in leaf shape and
coloration) exist and several poorly defined subspecies also have been
described. Naturalized plants in the midwestern United States correspond to ssp. ginnala.