The Art of Maple Tapping

Maples are unrivaled for their fall foliage coloring and variety of leaf shapes and textures. They are also grown for shade and timber. Many species are compact enough for the average garden. There are approximately 129 species that primarily grow in the northern hemisphere. Most species originate from East Asia, particularly China (with over 80 species), Japan, and the eastern Himalayas. Additionally, there are 9 species native to North America and a few to Europe, including Acer heldreichii subsp. trautvetteri (Greek maple). Most maples are deciduous, but there are a few evergreen and semi-evergreen species found in northern Turkey and the Caucasus.

The distinctive two-winged fruit, known as samaras, are more noticeable than the flowers, which are usually inconspicuous in most species. The bark is a notable feature in some maples, typically smooth and gray or greenish in color. Some maples, known as ‘snakebark maples,’ have longitudinal gray or red-brown stripes on their bark, while others have flaky or papery bark. Most maples prefer a cool and moist climate with ample rainfall in spring and summer. They thrive in planting positions sheltered from strong winds. Neutral to acidic soil conditions are ideal for showcasing their best fall colors. Maples can be propagated conventionally from seeds specific to each species. However, some species produce few fertile seeds, requiring a large number of seeds to be sown for sufficient seedling production. Cuttings are a challenging method for propagation due to the difficulty of inducing root growth in shoots. However, air-layering can be successfully performed on low branches.

Commonly planted maples:

Acer palmatum (Japanese maple)

The Japanese maple is the most widely grown maple in gardens. It is valued for its compact size, delicate ferny foliage, and brilliant autumn coloring that ranges from rich gold to the deepest blood-red. In a garden, it grows up to 12 to 15 feet, with a low-branching canopy and sinuous branches that form a dense and rounded crown. While it is more tolerant of warmer climates than most maples, it still requires shade and shelter to prevent leaf shriveling. There are over 300 cultivars available, ranging from rock-garden miniatures to vigorous small trees, each offering a variety of leaf shapes, sizes, and colors. Most Japanese maples need to be grafted to preserve their specific characteristics, making them relatively expensive.

Acer platanoides (Norway maple)

This species is a large, round-headed tree that thrives in a wide range of soils and conditions. It is found across Europe, from Scandinavia (where it can be reduced to a shrub) to the Urals, excluding the Mediterranean and British Isles, although it has been cultivated there for centuries. Yellow flowers appear before the leaves, and in autumn, the leaves turn golden to reddish-orange.

Acer x freemanii (Freeman maple)

This hybrid between Acer rubrum (red maple) and Acer saccharinum (silver maple) has foliage that is intermediate between its parent species. It can grow to 50 feet or more, featuring erect branches and a rounded crown. Freeman maples are often used as street trees and are typically propagated by layering.

Commercial maples:

Acer saccharum (Sugar maple)

This species is commercially important for its sap (used for maple syrup production) and durable timber. It ranges across eastern North America, from Newfoundland and Manitoba in the north to Florida in the south, and west to Utah. Regional subspecies exist in the south and west, including Acer saccharum subsp. floridanum, grandidentatum, leucoderme, and nigrum, which some botanists classify as distinct species. The sugar maple leaf is featured on the Canadian flag. While it can be slow-growing in the first ten years, it eventually becomes a low-branching, broad-crowned tree reaching 40 to 50 feet in height, or even taller in forests. Fall colors can vary, with yellow, orange, scarlet, and crimson being common. The Bigtooth maple (Acer saccharum subsp. grandidentatum), a widely distributed subspecies in western North America, features thicker leaves with bluish-white undersides contrasting with the deep green upper surfaces. It is a small, bushy-topped tree with pale bark that can reach up to 40 feet in height. Some attractive cultivars include ‘Globosum,’ ‘Green Mountain,’ ‘Legacy,’ and ‘Monumentale’.

Acer rubrum (Red maple)

Also known as scarlet maple, this large maple from eastern North America displays brilliant autumn colors of deep red, contrasting with the blue-white undersides of the leaves. In the wild, it can reach heights of up to 100 feet in forests on deep alluvial soil. When planted, it exhibits rapid growth with a straight trunk and narrow crown initially, but it spreads broadly as it matures. The timber of the red maple is highly prized for furniture making.

Acer pseudoplatanus (Sycamore maple)

This species occurs naturally from Portugal to the Caspian Sea and has long been established in England and North America. Cultivated trees typically reach heights of 40 to 60 feet and form a broad and dense crown of dark green foliage. The thick and scaly bark is pale gray. However, the leaves of this species do not exhibit significant fall coloration. Sycamore maple is commonly used as a park and street tree, preferring sheltered locations with deep, moist soil, although it can tolerate more exposed sites.

Acer macrophyllum (Bigleaf maple)

Bigleaf maple, also known as Oregon maple, is found in the wild from southern Alaska to southern California. It usually grows as an understory tree, but it can develop a broad, domed crown and a thick trunk, reaching heights of up to 100 feet. The leaves can grow up to 12 inches wide and turn gold and brown in autumn. Yellowish flowers hang in dense sprays, and the 2- to 3-winged fruits are approximately 3 inches across. This species prefers moderate shelter and deep, moist soil. Bigleaf maple is larger than other maple species.

Maple tapping often begins in late winter or early spring and typically lasts only a few weeks due to weather conditions. The sap extracted from maple trees, which has a high water content (approximately 96 to 99 percent), is commonly referred to as maple water. To produce maple syrup, the sweet and watery xylem sap is collected and concentrated. During the freeze-thaw cycle, the pressure buildup causes the sap to flow out of the maple tree trunks. It takes about 40 liters of sap (containing 2–3% sugar) to produce one liter of maple syrup with a sugar content of 66%.

In addition to sucrose, maple syrup’s flavor is a complex blend of various components, including minerals, amino acids, oligosaccharides, organic acids, phenolic and volatile aromatic compounds, as well as microbial contaminants present in the maple sap. The sap composition can vary throughout the seasons, and the color of the syrup tends to darken as the season progresses due to the presence of microflora. Syrup color can serve as an indicator of processing irregularities or microbial contamination.

Lighter maple syrups are typically sweeter and lack pronounced flavors, while darker syrups have a more intense, burnt caramel flavor and are often blended with lighter syrups to achieve a classic “maple flavor.” Darker syrups also contain higher levels of beneficial bioactive compounds such as polyphenols.

A stable maple syrup should not contain more than 10% moisture. Grade A maple syrup is classified into four color classes, which can be determined by either a transmittance value or the ratio between the intensity of light passing through the samples and the light emerging from them. At the beginning of the maple syrup harvest, the syrup is typically clear and mildly sweet. As the season progresses, the syrup darkens in color and develops distinct aromatic characteristics. Each color class is associated with a specific designation and accompanied by a description of taste. For example, gold color indicates a delicate taste, amber color indicates a rich taste, while dark and very dark color indicates a strong and robust taste.

Maple syrup is a delicacy prepared by boiling (conventional evaporation) or through reserve osmosis using sap obtained from various Acer species, primarily sugar maple (Acer saccharum Marsh, Acer nigrum, and Acer rubrum) trees. Among natural sweeteners, maple syrup is highly regarded as a superior alternative to refined sugar due to its mineral content and high concentration of phenolic compounds with bioactive properties.

In addition to maple syrup, these plants have a long history of traditional use in East Asia and North America for treating a wide range of diseases. They contain over 331 phytochemicals, including flavonoids, tannins, diarylheptanoids, phenylpropanoids, terpenoids, phytosterols, benzoic acid derivatives, simple phenolic compounds, phenylethanoid glycosides, and alkaloids. Some clinical studies have supported the use of maple as a medicinal plant, demonstrating its effectiveness in treating rheumatism, bruises, hepatic disorders, eye diseases, pain, and aiding in detoxification.

Furthermore, maples are a popular choice for bonsai and most of the species can be used. Dried maple wood can be used to smoke the food and some of the larger maple species have valuable timber.

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