Japanese maple (Acer palmatum) is one of Japan’s most famous ornamental trees. This guide includes identification features, bark, flowers, fruits, and photographs taken in Japan.
Overview
| Item | Description |
| Scientific Name | Acer palmatum |
| Common Name | Japanese Maple |
| Japanese Name | Iroha momiji |
| Family | Sapindaceae |
| Origin | Japan, Korea, China |
| Plant type | Deciduous trees |
| Height | 2–8 m |
| Flowering season | Spring |
What Is a Japanese Maple?
- The Japanese maple is one of the most iconic deciduous trees in Japan.
- The tree is known for its delicate palmate leaves, which display brilliant colors in autumn.
- Its brilliant autumn foliage has made it one of the most popular ornamental trees worldwide.
Identification Features
Leaves
・Young leaves of the Japanese maple are typically divided into five lobes, while mature leaves usually have seven to nine lobes. The outermost lobes are generally the smallest. Its Japanese name, “Iroha maple” (Iroha kaede), comes from the traditional Japanese iroha syllabary. The seven lobes of a mature leaf were said to correspond to the first seven characters of the sequence—”i, ro, ha, ni, ho, he, to”—giving rise to the tree’s popular name.
・The leaves are relatively small, measuring about 3–7 cm (1.2–2.8 in) across excluding the petiole, and are borne in opposite pairs along the branches. Among Japan’s native maples, this species has some of the smallest leaves, giving rise to the alternative name “Koha maple,” meaning “small-leaf maple.” The leaf tips are pointed, the margins are irregularly double-serrated, and fine hairs can be found at the base of the veins on the underside of young leaves. These hairs gradually disappear as the leaves mature.
Bark
The bark of young trees is green, gradually becoming pale grayish-brown with age and developing shallow vertical fissures. Compared with many maple species native to Europe and North America, the bark remains relatively smooth.
Japanese maples typically grow to about 15 m (49 ft) in height, although exceptional specimens may reach 30 m (98 ft). The trunk is often irregular or somewhat crooked, but the wood is occasionally used for timber and tool making. Mature trees may develop a trunk diameter of up to about 1 m (3.3 ft).
Flowers
Although often overlooked, the Japanese maple produces small, drooping deep-red flowers from April to May as the new leaves emerge in spring. The species is monoecious, with clusters containing both male and bisexual flowers. Each inflorescence typically bears around 20 flowers and hangs from the tips of the branches.
The flowers are about 5 mm (0.2 in) in diameter and have five sepals, five petals, and eight stamens. Bisexual flowers possess a flattened ovary and small, reduced stamens, whereas male flowers have well-developed stamens and a small, vestigial pistil. Another distinguishing characteristic of the Japanese maple is the absence of hairs on the pedicels and petioles.
Seeds
Following the flowers, paired winged fruits measuring about 1–2 cm (0.4–0.8 in) in length are produced. The fruits are green at first but ripen to red during the summer. Their distinctive wing-like structures aid in wind dispersal. In autumn, the fruits separate into two samaras, which spin through the air as they are carried by the wind.
Japanese Maple Varieties
The Japanese maple has a long history of cultivation in Japan. From the late Edo period to the early Meiji period, hundreds of horticultural cultivars were developed. While several hundred cultivars were once recognized, the origins and genetic backgrounds of many have since been lost. Major cultivars include the following.
Japanese Maple (Acer palmatum) – Growing Conditions
| USDA Hardiness Zones | ・Suitable for USDA Zones 5–8 ・Some cultivars can grow in Zone 9 if protected from intense afternoon sun. ・Extreme winter cold below about −29°C (−20°F) may damage young trees. |
| Light Requirements | ・Best growth in partial shade to full sun. ・In cooler climates (Zones 5–6), full sun is usually acceptable. ・In hotter climates (Zones 8–9), afternoon shade is recommended to prevent leaf scorch. ・Varieties with red foliage generally develop better color with several hours of sunlight each day. |
| Soil Requirements | ・Prefers moist, well-drained soil rich in organic matter. ・Grows best in slightly acidic to neutral soil (pH 5.5–7.0). ・Avoid heavy clay soils that remain waterlogged after rain. ・A layer of organic mulch helps maintain soil moisture and keeps roots cool. |
| Watering | ・Water regularly during the first two to three years after planting. ・Keep the soil evenly moist but not constantly wet. ・During hot, dry weather, deep watering once or twice a week is usually better than frequent shallow watering. ・Established trees are moderately drought-tolerant but perform best with consistent moisture. ・Excessive watering can lead to root problems and poor growth. |
| Additional Notes | ・Japanese maples have relatively shallow root systems and benefit from mulching around the base. ・Avoid planting in windy locations, as strong winds can damage leaves and increase water loss. ・Protection from intense afternoon sun and drying winds is especially important for finely dissected cultivars. |
FAQ
How fast does a Japanese maple grow?
Japanese maples (like Acer palmatum) are generally slow to moderate growers compared to many other trees.
Typical growth rate is
About 6–12 inches (15–30 cm) per year under normal conditions
Some faster varieties may reach 12–24 inches per year, but that’s less common
How tall does a Japanese maple get?
Many reach 10–25 feet tall over 10–20 years
Dwarf varieties may stay under 6–10 feet even when mature
Why are Japanese maple leaves turning brown?
Japanese maple leaves usually turn brown because of leaf scorch caused by heat, drought, wind, or intense sunlight. Poor drainage, overwatering, fertilizer burn, and certain diseases can also cause browning. Maintaining consistent soil moisture and protecting the tree from extreme conditions helps prevent the problem.
Can Japanese maple grow in full sun?
Japanese maples can grow in full sun, but they generally perform best when protected from intense afternoon heat. In warm climates, partial shade helps prevent leaf scorch and keeps the foliage looking its best throughout the growing season.
Is Japanese maple native to Japan?
Yes, the Japanese maple is native to Japan, but its natural range extends into Korea, China, Mongolia, and the Russian Far East. The tree is named for its long history of cultivation and cultural importance in Japan.