Acer morifolium Koidz.

(Sect. Macrantha)

Common names

Mulberry-leaf Maple, Yaku Maple

Article sources

New Trees

Shrub or tree 10–12(–15) m; usually multistemmed. Bark green with white longitudinal stripes. Branchlets shiny red or purplish red, tinged with green on the undersides, with scattered lenticels. Leaves deciduous, 5–9 × 2–4 cm, unlobed and ovate to cordate, or remotely three- or five-lobed, upper surface lustrous dark green and often bronzed, lower surface pale green with slight rusty pubescence, later almost glabrous, six to eight lateral veins on each side of the midrib, margins conspicuously double-serrate, apex acuminate or acute; petiole 3–8 cm long, bright red and grooved; autumn colour golden-yellow with hints of red. Inflorescence terminal, racemose, 6–10 cm long. Flowers yellowish green, 5-merous, usually dioecious; sepals narrowly oblong, ~0.15 cm long, petals narrowly obovate and same size as sepals, perianth segments partially fused, stamens eight, inserted outside the nectar disc. Samaras 1.5–2 cm long, yellowish brown when mature, wings spreading horizontally. Flowering April, fruiting September to October (Japan). Van Gelderen et al. 1994, van Gelderen & van Gelderen 1999; Gregory, in prep. Distribution JAPAN: Ryukyu Is., Tanega-shima, Yakushima. Habitat Warm, temperate forest. USDA Hardiness Zone 7–8. Conservation status Not evaluated. Illustration Wharton et al. 2005; NT93.

Acer morifolium is a very pleasant addition to the snakebark maples in cultivation and is likely to become popular as stocks are multiplied (ideally by cuttings rather than as grafts). It is closely allied to A. capillipes, which it rather resembles, but can be differentiated by the brownish (rather than white) hairs on its leaves. Young trees (at least) show good patterning on the bark, with reddish and white streaks on the dark green background. This coloration dulls and darkens somewhat with age. The leaves flush a good red, and pass through bronzed stages to become a dark green above, duller below, with very strong venation, but they are variable in their degree of lobing. This seems particularly to be associated with youth and vigour, as those on the more vigorous new shoots tend to have more pronounced lobing (up to five being visible occasionally). On mature shoots a simple outline, or very weak lobation, is the norm. The autumn colour is good, in shades between soft orange and red.

Despite the low altitude and southerly latitude of its origin, A. morifolium is surprisingly hardy. There are vigorous trees of this species at Westonbirt, and at Hergest Croft (from BSWJ 6037, collected at 100 m on Yaku-shima in 1998) (B. Wynn-Jones, pers. comm. 2007), and it is also reported to be thriving very well at the David C. Lam Asian Garden in Vancouver (Wharton et al. 2005). The Vancouver material was collected at 180 m on Yaku-shima by Dr M. Tsukada of the Forest Experimental Station (University of Tokyo), Hokkaido (P. Wharton, pers. comm. 2007). The species arrived in the Netherlands from Japan in the early 1990s, since when it has been introduced on several occasions via different routes, some material in the United States being received from Chollipo Arboretum, for example (Heronswood Nursery catalogue 2000). Several variegated clones are known in Japan (Yano 2003).

Genus

Acer

Other species in the genus