There are several species of garden-worthy native trees, shrubs, and vines that make their home in the shade of taller trees. Included in this group are the pagoda dogwood (Cornus alternifolia), an understory tree with horizontally-spreading branches trimmed in early June with upright flat-topped clusters of creamy-white flowers; Virginia creeper (Parthenocissus quinquifolia), an exuberant vine with bold scarlet autumn foliage; and our native honeysuckle (Lonicera canadensis), an early May-flowering shrub with lovely pale-yellow blossoms quickly followed by bright red fruits.
All three of these native woodies grow at the back of Marjorie’s Garden under the shade of red oak and bird cherry. In early June, however, the dogwood must share center stage with a rarely-cultivated native maple.
Known as mountain maple in the Great Smokies of Tennessee and North Carolina where it grows as a thirty-foot tree, Acer spicatum is often reduced by deer and moose browsing to a large multi-stemmed shrub in New England forests, hence the alternate common names of moose maple – a name it shares with another native maple, A. pensylvanicum - and low maple. Yet another common name, water maple, refers to its mountain habitat, described by Donald Culross Peattie as “the neighborhood of white and singing water”.
In Maine I have found examples of both growth habits, tree form and shrubby. My introduction to the species was a lovely small tree growing in the shade of tall pines near Boothbay where a former student and I were collecting data for her research project. It was near dusk and the small maple was in full flower, the upright spikes of greenish-yellow flowers turning horizontal branches into candelabras.
I was so enchanted by the tree that I returned later with the intent of collecting seed, only to find the tree nearly destroyed by timber harvesters dragging pine logs out of the woods. Only one of the original three trunks had survived to mature a handful of seeds on its branches. I collected these seeds and successfully produced seedlings, two of which now grow at the back of Marjorie’s garden.
Mountain maple is easily grown from seed sown outside in fall or stratified in the refrigerator for three to four months followed by spring sowing. Considering the scarcity of this species in nurseries and garden centers, growing your own from seed may be the only way to bring this lovely maple from woods to garden.
Mountain maple deserves to be more frequently grown in shady gardens. In June, its shoot tips are graced with upright spikes of chartreuse flowers that glow like candles in the understory. Small two-winged samaras ripen through the summer to red or yellow before they are carried off on autumn winds as the the tree’s foliage turns to yellow, orange and scarlet. In winter months, the tree’s bright red young twigs add a touch of color to the snow-covered landscape.
An inhabitant of beech-maple-hemlock woods, hemlock ravines, and pine forests, mountain maple demands shade. Scorching of the leaves and the thin bark occurs when it is exposed to full sun, a trait which it shares with the striped maple, the other moosewood. A sheltered location protects the weak wood of both species from damage by wind.
Mountain maple is not tolerant of urban stresses, such as soil compaction and pollution. It is intolerant of flooding and its shallow roots, seldom more than a few inches below the soil surface, make it very susceptible to drought. On the plus side, it can be grown from USDA Zone 2 to the mountains of Zone 7 and it has no serious insect or disease pests. Both A. spicatum and A. pensylvanicum are among the most resistant of all maples to attack by the Gypsy moth.
Europeans have long recognized the garden worth of mountain maple, first introduced in 1775 and again in 1905. Like many gardeners in the United States today, they had a penchant for the exotic. For many of us, however, there is growing interest in sustainable managed landscapes that express the uniqueness of native flora. Plants like mountain maple have come into their own.
Complete coverage of native woody plants for New England landscapes can be found in my upcoming book, The New England Gardener’s Year. Visit the book’s Facebook page (http://www.facebook.com/negardener) for updates on publication dates (ebook and print versions) and advance ordering in time for Christmas giving.