A hardwood, the maple is an ancient tree. Most maples are deciduous, though Acer lacarinum, a tree of the tropics, is evergreen. The maple is a collection of species in the genus Acer, which derives from the Indo-European ac, meaning “sharp.” The name may derive from the pointed leaves of a maple, though there is nothing particularly sharp about them. Nevertheless, the German for “maple,” Spitzblatt, and the Russian ostrolistny klejen mean “sharp leaved.” Another possibility is that maple wood is hard and was used to make pikes and lances. In this context, maple wood was indeed sharp. The Dutch Saanse aak means “maple.”
Maple tree tapped for syrup (Edward Fielding/Dreamstime.com)
Curiously, the word aak may be the root of “oak,” a tree unrelated to maple. Whatever its origin, the Latin Acer is neuter despite the custom of referring to trees as feminine. By the 18th century, Acer was the common label for maple, and Swedish naturalist Carl Linnaeus, bowing to tradition, assigned the nine species of maple he knew to its genus. The Greek for maple is gleinas or gleinon. From it have arisen the Polish klon, the Lithuanian kleveas, the medieval Latin clenus, the Middle High German linboun or linboum, the Lower High German lehne, the Swedish and Norwegian leonn, the Danish lam, and the Gutnish leund.
Origin, Diffusion, and Distribution
One hypothesis holds that the maple originated in Hubei, Sichuan, and Yunnan provinces of China. The oldest fossil of a maple dates to 100 million years ago in Alaska. Had the maple originated in China, it must have migrated to Alaska and so must be older than 100 million years. By 90 million years ago, in addition to Alaska the maple had colonized Greenland, Spitsbergen, and Iceland. Fossils from the Paleocene and Eocene Epochs (65-38 million years ago) place the maple in several regions of North America. Fossils of the Middle Eocene Epoch place the maple in Wyoming. The oldest fossil in Europe, from the species Acer haselba- chensis, dates to 38 million years ago. The Miocene Epoch (25-5 million years ago) marked the apex of the maple, which was more widely distributed than at any time before or since. The maple even colonized lands near the poles. The warm climate allowed the maple to range far from the equator. The onset of the ice ages in the Pliocene Epoch (5-1.7 million years ago) forced the maple to retreat to what is today the temperate zone. As its geography contracted, the maple’s population shrunk. From its putative origin in China, the maple spread west across the Himalayan Mountains to Iran, Afghanistan, Turkey, the Balkans, and Europe; south to Southeast Asia, Malaysia, Indonesia, and the Philippines; and northeast to Manchuria, Korea, Japan, Siberia, and across Beringia to North America, Greenland, Iceland, and Spitsbergen.
Principally a temperate plant of the Northern Hemisphere, the maple tree is found in North America, Europe, Asia, and North Africa, but also in tropical Southeast Asia. Specimens grow in the mountains of the Philippines, Sumatra, Borneo, Sulawesi, and Malaysia. One may find them in the sunny climate of the Mediterranean Basin, including North Africa, and Mediterranean California. The maple tree grows in the Balkans, Lebanon, Turkey, Iraq, Iran, Afghanistan, Pakistan, the Himalayas, China, Japan, Korea, Manchuria, Siberia, and the Kurile Islands. In the United States, the maple has colonized every locale but the southern tip of Florida and southwestern California. It occupies all of temperate Canada.
The primary use of the maple is to landscape public and private spaces. Landscape architects favor Acer saccharum and Acer rubrum for their fall colors. Acer diabo- licum has gained adherents because of its showy flowers. Acer macrophyllum, yielding yellow flowers, is especially pretty in spring. Landscapers have planted maples in public parks and gardens in North America, Europe, Asia, and Africa. As late as 1959, 17 percent of trees planted along streets in Berlin, Germany, were the maple. Only the genus Tilia claimed a larger percentage. Acer platanoides graces the esplanade in Helsinki, Finland. The Netherlands has planted Acer pseu- doplatanus along its roads, though the tree is ill suited for this purpose. Its roots, growing near the surface of the soil, swell to such a large diameter that they uplift streets and sidewalks. Since the colonial era, Americans have planted the sugar maple along roads. In China, Acer truncatum serves this function. Acer buergeria- num is planted along streets in Japan, Korea, and Pretoria, South Africa. The people of Southeast Asia plant Acer laurinum along roadways in Indonesia, Malaysia, and the Philippines.
Because maple wood lacks tannin, it is not naturally weather resistant and so is not ideal for use outdoors. It decomposes when in contact with the soil and when exposed to weather. Nonetheless, its wood has been in demand since antiquity.
According to first-century BCE Roman poet Virgil, the Greeks built the Trojan horse from maple. Today, maple is a popular wood for the floors and walls of homes, bowling alleys, gymnasia, and other structures. The interior beams of buildings are often maple. Woodworkers make maple into furniture. The soft wood of Acer macrophyllum, Acer rubrum, and Acer saccharinum is suitable for making kitchen utensils and wooden tools. Violin makers use the species Acer pseudoplatanus to make the back, sidewalls, and pegs of violins.
Several species of maple yield honey, though maple trees are better known as a source of syrup. Acer saccharinum (the sugar maple) is the species of choice. Its sap is 1-3 percent sugar, being mostly water. It does not taste especially sweet and may have gone unnoticed but for the fact that Native Americans called attention to it. They taught Europeans to make syrup through the simple process of boiling the sap. By driving off the water, the maker derived syrup. When boiled, eight gallons of sap yielded one gallon of syrup. The colonists, eager for a cheap substitute for sugar, produced maple syrup in quantity. Acer saccharinum produces sap in early spring. Sap flows as the temperature rises during the day. The principal producers of maple syrup are Quebec, Canada, and New Hampshire, Vermont, New York, West Virginia, and Ohio in the United States.
The ancients did not regard the maple as a medicine. First-century CE Greek physician Dioscorides did not mention it, and it did not appear in the medical texts of China and Japan. Nonetheless, the species Acer negundo yields a drug suitable for chemotherapy. A maple tree also contains glycosides that, while not a medicine, are an insect repellant and insecticide. They protect the wood from termites.
Attributes and Cultivation
Maples grow in all types of soil, though most prefer a pH between 5 and 6.5. Acer campestre and Acer monspessulanum are atypical in preferring alkaline soil. Where the soil is too basic, the gardener may add compost, leaves, and peat to it. Maples prefer well-drained soil. They will not tolerate waterlogged soil. Japanese maples do poorly in windy conditions. Cold or salty wind is particularly damaging. Other species are more tolerant of wind.
The maple languishes in shade, though where temperatures exceed 90°F, partial shade at midday is desirable. A maple with poor color likely does not receive enough sunlight. Purple-leaf maples especially need full exposure to the sun. A maple tree should be planted when dormant: between late fall and early spring. Where the soil freezes in winter, the gardener should plant a maple tree in early spring. Because a maple tree has shallow roots and cannot tolerate dry conditions, it should not be planted during the rainless days of summer. The gardener should dig a hole twice the size of the root ball so that the roots may expand. Before planting a tree, the gardener should add compost to the hole. Once planted, a tree should be watered where the climate is dry.
Once fertilized, the flowers yield seeds, which have wings that resemble helicopter blades. The wind disperses seeds. The gardener who wishes to propagate a maple tree may gather seeds from the ground, refrigerate them for 60 to 120 days to stratify them, and plant them in potting soil. Growth is not rapid. The gardener must nurse a seedling one to three years before it is ready for transplantation outdoors. A tree grown from seed is unlikely to be as spectacular as one sold by a nursery. A maple tree may also be propagated by a cutting, though weeping maples are difficult to propagate is this fashion.
Species and Varieties
One authority asserts that maples are “trees of perfection.” Their palmate leaves have 5 to 9 and sometimes 11 lobes. Not all maples have green leaves in spring and summer. Acer palmatum, known as Bloodgood, has dark purple leaves. The variety Orido-nishiki has pink and cream leaves. Beni-kamachi has scarlet leaves. Shi-deshajo has pink leaves. Acer platanoides, known as the Crimson King, has, as the name suggests, dark red leaves. Acer pseudoplatanus, like the variety Shi-deshajo, has pink leaves. In autumn, this species yields red, golden, crimson, and orange foliage. Acer japonicum and Acer japonica produce conspicuous flowers, yielding them before they put forth their leaves in spring. Other species, producing leaves and flowers simultaneously, are less showy.
The subspecies Acer palmatum atropurpureum is the most widespread red maple. Its leaves are, according to one authority, “black-red.” The tree reaches 25 feet in height. The variety Okagami of this subspecies grows only half as tall. Its leaves are dark red in spring and scarlet in autumn. Another variety of this subspecies, Oshio-beni, grows 18 feet tall. In spring, its leaves are orange and red, in the summer red-green, and in autumn scarlet. A third variety, Moonfire, grows 12 to 15 feet tall. Its dark red leaves hold true in spring, summer, and fall. A fourth variety, Suminagashi, grows to 12 feet. It has red leaves in spring, maroon in summer, and crimson in autumn.
Acer buergerianum originated in China, but the work of Japanese horticulturists has led to its renown as a Japanese maple. Atypical of maples, this species tolerates dry conditions. Because it is impervious to pollution, it has been planted in cities. In spring, it bears green leaves, which turn red and orange in autumn. Like Acer buergerianum, Acer griseum originated in China but is known as a Japanese maple. Called the paperback maple, the tree displays orange-brown bark. The species holds its leaves, which turn red in autumn, until late in the season.
Acer japonicum, known as the full-moon maple, grows to 30 feet. Its purple-red flowers attract admirers. The Asconitifolium variety of this species has leaves that resemble the fronds of a fern. It yields red flowers, and its green leaves turn red, yellow, crimson, and orange in autumn. The variety Vitifolium derives its name for the resemblance of its leaves to grape leaves. Its green leaves turn golden, scarlet, and crimson in fall.
Acer ciriatum—the vine maple of North America—resembles Acer japonicum except that the American maple has sticky leaves. One authority characterizes the color of its flowers as “wine and white.” The name vine maple derives from the species’ way of surviving in shade. When overshadowed by a large conifer in the forest, the vine maple winds its way up the conifer to sunlight. A small tree Acer ciriatum grows to 15 feet. The dwarf of this species, Little Gem, grows to only 3 feet. Because of its smallness, Little Gem may be grown in a container.
Barrett, Rosemary. Maples. Auckland, New Zealand: Firefly Books, 2004.
Harris, James. The Gardener’s Guide to Growing Maples. Portland, OR: Timber Press, 2000.
van Gelderen, D. M., P. C. de Jong, and H. J. Oterdoom. Maples of the World. Portland, OR: Timber Press, 1994.