Scientific Name: Acer buergerianum
Common Names: Trident Maple, three pronged maple, san jiao feng, Chinese ahorn, tokaede
Cultivars: Acer b. formosanum, the Taiwan or Formosan Trident.
‘Eastwood Cloud’ – Almost pure white spring foliage, that slowly turns to a creamy pink and finally light green. Slower grower than the species.
‘Goshika Kaede’ – a pink and green variegated form with smaller leaves than the species.
‘Evergreen’s Rough Bark’ – valued for its bark appearance.
‘Kifu Nishiki’ – Rounded, almost unlobed leaves.
‘Kyuden’ – dwarf variety with short internodes and distorted leaves.
‘Mino Yatsubusa’ – Dwarf characteristics with long, narrow leaves.
‘Mitsubato Kaede’ – cork-like bark and short internodes.
‘Miyasama’ – naturally short internodes.
‘Miyasama Kaede Yatsubusa’ – Dwarf characteristics
‘Natuto’ – Notable foliage that forms a sharp pointed “T” with strongly involute (rolled) margins.
‘Nusatori yama’ – Foliage of this cultivar is almost entirely white, sometimes with rose overtones. Difficult to grow, rare cultivar.
‘Streetwise’ – good autumn colour and bark that exfoliates at an early age
‘Tancho’ – rolled edged foliage similar to ‘Naruto’
‘Wako nishiki’ – Variegated dwarf cultivar. Naturally tiny leaves.
Trident maples are a deciduous tree well suited for general bonsai cultivation. With multiseason appeal, these trees are adaptable and forgiving even of some of the worst blunders. Fast healing and fast growing, they are good for the novice and advanced bonsai practitioner alike.
Anatomy: Part of the Aceraceae family, Trident Maples are native to Eastern China, Taiwan and Korea, though now can be found across much of the northern hemisphere. In the landscape, Tridents are prized as shade trees that can grow in rather poor soil and are rather adaptable to city and suburban life as they have a high tolerance to air pollution. Growing up to 65ft(20m), though more typically to around 30ft (9m), they have a wide, low spreading habit, though the low growth is often pruned to offer a more typical sillohuette of a shade tree. They can be found in the landscape both as single trunked and multitrunked specimens, both styles suitable in bonsai cultivation.
Foliage: Glossy leaves have three short lobes closely set at the upper end, usually between 1-3in(2.5-7.5cm) across and in opposite pairs. Young trees often have slightly serrated edges, while more mature trees will have smoother margins. New growth is often bronze, changing to a medium to deep green with a paler underside in the summer and turning yellowish, sometimes flushed with red and orange in autumn.
Stem and Trunk: Bark is flakey and pale grey to orange-brown, though can retain a pink hue when grown in pot culture.
Flowers/Fruits/Seeds: Trident maples are monoecious (having seperate male and female reproductive units on the same plant). Flowers occur in spring- small and inconspicuous pednulous clusters of yellow-green. Winged fruit (sometimes called “keys”), consisting of two seeds, called “samara”, are abundant and often persists through the winter. The fruits wings point foreward and often overlap eachother.
Hardiness: Zone 5 in the landscape. Recommended zone 7 in a bonsai pot. Trident maples need early winter protection before the first freeze, as fast growing root systems are particularly prone to frost damage. Try to keep potted tridents at temperatures above 20F. Protect from prolonged periods of deep freeze by keeping in an unheated garage or shed once leaves have dropped. According to several sources, when the thick roots on a Trident Maple freeze, they can literally burst, much like frozen water pipes, though I have never experienced this personally. Regardless, a combination of frost protection and not letting the soil remain too wet before a freeze is essential. They are also susceptible to late spring freezes, and once the buds begin to swell should continue to be protected against sudden cold snaps of temperatures below freezing.
Light: Full sun. Midday protection can be offered, especially to help keep the pot cooler in the summer. Trident maples can tolerate partial shade. Drying winds can cause leaf scorch, and the trees should be protected from heavy winds at all times.
Soil: Slightly acidic, fast draining soil. These do fantastically in pure akadama or turface or pot in a standard bonsai mix, though with a slightly higher percentage of grit. Chopped sphagnum moss, with it’s acidic nature, is a good choice for organic material in a trident’s soil mix.
Watering: Daily watering during growing season, as the fast growing roots have a very high water content. Do not allow to dry out, but hold water if the soil is still too moist. Though they can handle dry periods when in the landscape, Trident maples do not tolerate drought conditions at all in bonsai cultivation.
Fertilizer: For trees in early development and growth, use a balanced or a high nitrogen, diluted fertilizer every two weeks through the growing season once the leaves have opened. Older more mature trees will respond better to a lower nitrogen slow release formula to control leaf size and general growth. Consider dosing occasionally with an acidic fertilzer (like one used for azaleas). Substitute a nitrogen free formula in late summer or fall.
Pests and Diseases: Generally pest free. Anthracnose, leaf spot, and powdery mildew (usually due to poor air circulation around the leaves and easily remedied). Chlorosis can occur if the soil pH is over 7.0. Aphids, boreres, scale and white flies. Verticillium wilt can be fatal.
Repotting: Every year in spring for young trees, every 2-3 years with older trees, before the buds open. Trident maples can tolerate severe root pruning.
Pruning and Styling: Cut back tips of new shoots, leaving two new pairs of leaves for younger trees and a single new pair for older, in spring and summer as needed through the growing season. When two new shoots appear at a node, clip and keep one pair of leaves per shoot. This was the crown will develop good ramification, a fine network of branches. Healthy trident maples can be defoliated in the summer to reduce leaf size and increase ramification. Trunk chopping is a viable option, done in late winter or late spring. Trident’s bounce back well and will reward you with a flush of new growth and branches forming. Trident maples backbud well to old wood.
Trident maples will frequently heal roughly, leaving large bulges and scars where pruning was done on large branches and the trunk. Care must be taken to hollow out, clean and smooth any pruning wounds to prevent unsightly bulges. By making the wounds concave, rather than simply flush with the trunk, the scar tissue will fill the space, rather than creating a large bulge. Two different schools of thought exist on pruning of large banches on maples. One is to do serious pruning of large branches after leaf fall in autumn or late winter when the tree is dormant. The other is to do pruning of large branches in early spring or late summer to give the tree a chance to heal before winter. These recommendations seem to come about equally in different references.
Wire: Wire with care as the bark is easily marked and growth is fast. Check frequently to keep wire from biting into the bark. Wiring can be done at any time during the growing season, though because of the fast growth of tridents, mid to late summer is best. If you wire in spring, be prepared to remove and rewire sometime during the growing season.
Leaf Reduction: Leaf pruning can be done in midsummer to encourage a new crop of smaller leaves. Trident maples react well to full or partial defoliation (though partial defoliation, of up to a half of the leave mass, is less stressful on the tree), but only attempt if the tree is very healthy and has been growing vigorously. If partial defoliate is chosen, remove foliage evenly all over the tree, rather than defoliating complete areas. Completely defoliating a single branch or two is more likely to result in the maple ignoring those branches to favor the branches that still retain leaves. Do not defoliate every year, as it does put undo stress on the tree. Defoliation can result in better autumn colour.
Jin/Shari: Trident maple wood rots easily. Carved trunks are not uncommon, however the bare wood should be treated with a wood preservative/hardener.
Styles and Forms: Broom, group and forest plantings, raft, and clump styles, though they can be grown in almost any manner. Because of the species rapid root growth, these are well suited to stunning root-over-rock plantings.
Seeds: Indoors-Soak seeds in hot water for at least 24 hours, no more than 48 hours. Place in moist, but not wet, soil. Fresh seeds may germinate very quickly, but germination can be erratic. If they do not germinate in 60 days at room temperature, moist chill for at least 60, but no more than 120 days is possible before returning to room temp. Another method is to cold store them in the refridgerator immediately upon sowing for up three months. Dry stored seeds have a low germination rate, and seeds are best when collected fresh or from a reputable dealer. Maples germinate best in full sun, but do not allow the soil to completely dry out.
Outdoors- sow outside as soon as ripe, ignore till spring, other than making certain soil medium doesn’t dehydrate completely.
Cuttings: Hardwood cuttings (4-6 in/10-15cm long) in late winter, early spring. (Softwood cuttings (4-6 in/10-15cm long) in early to midsummer as new growth is just starting to harden off. Larger cuttings may be taken, and there are even reports of cuttings several inches thick rooting well. Trident maples have a period of extremely strong root growth in the two weeks prior to budding, which may be a good time to take larger cuttings, as they are more prone to send out new roots during this time.
Layering: Airlayer and ground layering in spring.
BCI Trident Maple Entry –
Evergreen Garden Works: Acer –
Bonsai Learning Center Trident Maple –
http://www.bonsailearningcenter.com/Tip … tmaple.htm
Bonsai Survival Manual Colin Lewis, 1996
Trees and Shrubs Ernie Wasson, Tony Rodd, 2004
Growing Shrubs and Small Trees in Cold Climates Nancy Rose, Don Selinger, and John Whitman, 2001
Japanese Maples, Third Edition, J.D. Vertrees, 2001
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