1273 Acer buergerianumCommon Names: trident maple,three-toothed maple Family: Aceraceae (maple Family)
Trident maple is a rather small, wide spreading, often bushy, tree, reaching up to 20-30 ft (6-9 m) tall with a similar spread. The leaves are around 2-3 in (5-8 cm) long and 3-4 in (8-10 cm) wide, with three triangular lobes, often pointing forward, like a trident. They are purplish to bronze when they emerge in spring, becoming dark green above and bluish green on the undersides, then turning orange and red in autumn. The fruits are samaras about an inch (2.5 cm) long with wings that can be horizontal and parallel to each other, or converging, even touching each other above the nutlet, a condition called connivent. Three varieties are recognized. Acer buergerianum var. formosanum has leaves with wide triangular lobes that point forward, and samaras with horizontal wings. Var. ningpoense has bluish green leaves with wide lobes that point distinctly sideways, and samaras with wings that converge above the nutlet. Var. trinerve is a smaller shrub, to just 20 ft (6 m) in height, and usually much less. Its three narrow lobes are deeply incised and irregularly toothed, and its fruits have horizontal wings.
The cultivar, ‘Maruba Tokaede’, probably a selection of Acer buergerianum var. ningpoense, has rounded leaves with blunt lobes if it has any lobes at all. ‘Streetwise’ ® is a new selection from a commercial grower in Athens, Georgia, said to have foliage that reliably turns wine red in autumn. The Japanese have developed several cultivars that are (unfortunately) rarely found in the West: 'Goshiki Kaede' has variegated pink and green leaves; 'Kifu Nishiki' has leaves that are rounded and lack lobes; 'Mino Yatsubusa' is shrublike and has long, narrow leaves.
The three varieties of Acer buergerianum are native to Japan, Korea and eastern China. Although trident maple in cultivation is typically a small, bushy shrub-like tree, in its native forest habitat in eastern China, it grows to an impressive 100 ft (30 m) or more in height.
Light: Grow trident maple in dappled shade or where it gets morning and/or late afternoon sun, but not full sun at midday. Moisture: The Japanese maples do best in soils that are on the moisture retentive side, but still free draining. Soils that do not dry out in summer nor become waterlogged in winter are ideal. Ph should be neutral to slightly acidic. Trident maples grown in alkaline soils develop yellowing of the leaves. The best autumn leaf color occurs when the maples experience some drought stress in late summer and early fall. Established specimens are fairly drought resistant compared to other maples. Hardiness: USDA Zones 5 - 9 . In zone 9, trident maple will need midday shade in the summer. Propagation: Plant seeds as soon as ripe, preferably outdoors. For seeds that have been dried and stored, soak in water for a day or two, then stratify in damp sand for 2-4 months at 34-46° F (1-8° C). Cultivars are grated onto seedling of the species. Although difficult and with limited success, cuttings from fast growing stem tips can be rooted under mist.
Trident maple makes a handsome specimen in a small landscape or courtyard. They are used as street trees in Japan, and said to tolerate air pollution. Trident maple would be a nice little shade tree over a detached deck. They are sometimes grown in containers on the patio. Leafless in winter, the exfoliating bark reveals multiple shades of brown and gray and makes this little specimen tree appealing in all seasons. The Japanese maples are the most frequently used deciduous plants for bonsai, and trident maple is one of the favorites.
Trident maple is one of several Japanese maples that so elegantly grace well managed gardens in Japan and, increasingly, in the West. They should be used as street trees more often due to their small size, attractive habit, and tolerance of salty soils, air pollution, and irregular watering .
Steve Christman 10/5/16