Acer pensylvanicum Seeds | Striped Maple
LATIN NAME: Acer pensylvanicum
COMMON NAME: Striped Maple, Moosewood
Plant Profile
Striped maple is a small deciduous tree or large shrub of the soapberry family, five to ten metres tall, with a short trunk and a wide, layered crown of large, three-lobed leaves. It grows in the understorey of cool, moist forest, and it is one of the most elegant small trees in the North American flora, though it is rarely seen outside its native range.
The bark is the reason for the name. On young stems it is smooth and bright green, marked with narrow, vertical white stripes that run between the leaf scars, and it looks almost painted. As the tree ages the bark turns brown and the stripes fade, and on old trunks it becomes rough and scaly, so the character is a young tree’s feature and should be enjoyed while it lasts.
The leaves are large for a maple, up to twenty centimetres across, with three forward-pointing lobes and a finely toothed margin, and they turn a clear, soft yellow in autumn rather than the red of the sugar maple. The flowers are yellow-green, in drooping racemes, and they appear with the leaves in spring; the fruit is a paired samara with widely spread wings.
Its range covers the mountains and cool forests of eastern North America, from Nova Scotia to Georgia, in the understorey of beech, birch and hemlock forest. It is a tree of shade and of acid, moist, well-drained soil, and it is one of the first species to decline when a forest is opened up or grazed.
Science & Biotechnology
Striped maple is one of the few trees known to change sex. Individual plants can function as male in one season and as female in another, and the switch appears to be related to size, to light and to the previous year’s fruit crop. The phenomenon, sequential hermaphroditism, has been studied in this species because the flowers are relatively easy to score and the populations are accessible, and it is one of the clearest cases documented in a temperate tree.
The green bark is photosynthetic, and this is a genuine adaptation to life in deep shade. Young stems can fix carbon through the bark, which supplements the limited light reaching the leaves and helps the plant survive under a closed canopy. The white stripes are lenticels, pores that allow gas exchange, and their arrangement is what gives the stem its striped appearance.
The species is an understorey specialist, and its ecology reflects that. Seedlings grow slowly, they tolerate deep shade for decades, and they respond to a canopy gap with a burst of growth. Seed production is irregular, and the seed requires cold, moist stratification; germination is often poor, and much of the seed is eaten by rodents before it can germinate.
The common name moosewood comes from the fact that moose browse the twigs and bark in winter, and the tree is also eaten by deer, beaver and porcupine. Its palatability is one reason it is scarce in forests with heavy deer pressure, and it is used as an indicator of overbrowsing in some woodland studies.
Uses & Benefits
In the garden it is a specimen for a shaded woodland, a north-facing border or a cool, acid site, where its striped bark and soft yellow autumn colour can be seen. It is not a tree for a hot, dry or exposed position, and it needs shade for at least part of the day. It is slow, so it is best bought as a small container plant and planted where it will not be disturbed.
The wood is soft, light and of little commercial value, and it is used only for small carvings and for fuel. The bark has been used in folk medicine by Native American and settler communities as an emetic and a cough remedy, and the twigs were brewed as a tea, but the practice is historical and not supported by modern evidence.
Ecologically the tree is an important understorey component of the northern hardwood forest, providing cover for small birds and mammals and early pollen for bees. Its decline is one of the signs of deer overbrowsing and of the loss of closed-canopy forest, and it is therefore a useful indicator species for woodland managers.
For a gardener interested in native plants, striped maple is a good choice for a shady corner where little else will grow, and it is one of the few trees that gives winter interest from bark alone. It is also a good subject for a large container in a shaded courtyard, where its green-and-white stems can be seen at eye level.
Growing from Seed
Seed requires cold, moist stratification for ten to twelve weeks, and germination is often poor and uneven. Sow in autumn, in a shaded frame, in a loose, humus-rich, acid mix, and cover lightly; or stratify in damp sand at two to five degrees and sow in spring at fifteen to eighteen degrees. Leave the tray for two seasons before giving up, since some seed germinates in the second year.
Grow the seedlings in deep shade, in a cool, humid place, and keep the mix consistently moist but never wet. Plant out into a shaded, sheltered site with acid, humus-rich soil, and mulch with leaf mould. Protect the young stem from deer and from rabbits, since it is highly palatable, and water through the first two summers. The tree is slow and should not be pruned hard, as it does not regenerate readily from old wood.
Our Take
Striped maple is the tree for the shaded, acid corner that defeats everything else: elegant, unpushy and quietly strange, with green bark that photosynthesises and a sex life that changes from year to year. It is not a tree for a hot garden or an impatient gardener, but in the right place it is one of the most rewarding small trees you can grow.
Related Reading
Gardeners who grow Striped Maple often pair it with these related subjects: