Acer palmatum, called Japanese Maple or Smooth Japanese Maple is a species of woody plant native to Japan, Korea and China. Many different cultivars of this maple have been selected and they are commonly grown in other parts of the world too, for their attractive leaf shapes and colors. They are highly sought after and are relatively costly trees given the size.
Acer palmatum is a deciduous shrub or small tree reaching heights of 6–10 m, rarely 16 m, often growing as an understory plant in shady woodlands. It may have multiple trunks joining close to the ground. In habit, it is often shaped like an upside-down circle (especially when younger) or takes on a dome-like form, especially when mature. The leaves are 4–12 cm long and wide, palmately lobed with five, seven, or nine acutely pointed lobes. The flowers are produced in small cymes, the individual flowers with five red or purple sepals and five whitish petals. The fruit is a pair of winged samaras, each samara 2–3 cm long with a 6–8 mm seed. The seeds of Japanese maple and similar species require stratification in order to germinate.
Even in nature, Acer palmatum displays considerable genetic variation. As such, even seedlings with the same parent tree can show difference in such aspects as leaf size and shape, and colour.
(1) A. palmatum var. Thunbergii, Pax (A. palmatum, Thunb.). Lvs. deeply 5-9-lobed or cleft; lobes oblong-lanceolate, coarsely and doubly serrate or incised. Var. atropurpureum, Van Houtte (var. nigrum, Hort.). Lvs. dark purple, coarsely doubly serrate. Var. sanguineum, Carr., is lighter red than var. atropurpureum. Var. bicolor, Koch (var. atropurpureum variegatum, Hort.). Lvs. dark purple, with large carmine blotches, the lobes half purple and half carmine. Var. aureum, Nichols. Lvs. yellow. Var. versicolor, Schwerin (A. polymorphum septemlobum versicolorum, Van Houtte). Lvs. bright green, with large white spots. Var. roseo-marginatum, Schwerin (A. polymorphum roseum marginatum, Pynaert). Lvs. small, deeply cut, with narrow pink margin. Var. crispum, Andre. Lvs. small, with involute margins; of distinctly upright growth.
(2) Var. septemlobum, Koch (A. septemlobum, Thunb.). Lvs. mostly 7-lobed; lobes broad, equally doubly serrate. Var. rubrum, Schwerin. Lvs. large, deep red when young, becoming almost green later. Var. reticulatum, Andre. Lvs. greenish yellow, with green margin and dark green veins. Var. tricolor, Nichols. Lvs. with red, pink and white spots.
(3) Var. linearilobum, Sieb. & Zucc. (var. scolopendrifolium, Hort., not Schwerin). Lvs. divided nearly to the base; lobes linear, remotely serrate or nearly entire. Var. atrolineare, Schwerin (var. linearilobum atropurpureum, Nichols.; var. pinnatifolium atropurpureum, Hort.). Lvs. dark red.
(4) Var. dissectum, Koch (A. polymorphum var. decompositum, Sieb. & Zucc. A. polymorphum palmatifidum, Van Houtte). Lvs. divided to the base in 5-9 pinnatifid lobes. Var. ornatum, Carr. (var. dissectum atropurpureum, Hort.). Lvs. deeply cut deep red. Var. Frederici-Guilelmi, Carr. (var. pinnatifidum roseo-pictum, Lem.). Lvs. finely cut, green, with white and pink spots.
(5) Var. sessilifolium, Maxim. Lvs. deeply cut, with very short petioles. G.C. II. 16.—Of little decorative value.
More information about this species can be found on the genus page.
Acer palmatum includes hundreds of named cultivars with countless forms, colors, leaf types, sizes, and preferred growing conditions. Heights of mature specimens can range from 0.5 m to 25 m, depending on type. Some tolerate sun, and others like shade. Almost all are adaptable and blend well with companion plants. The trees are particularly suitable for borders and ornamental paths because the root systems are compact and not invasive. Well drained soil is preferred, and the trees grow strongest when not over-fertilized. Many varieties of Acer palmatum are successfully grown in containers.
A decidious Tree growing to 8m by 6m.
The plant prefers light (sandy), medium (loamy) and heavy (clay) soils, requires well-drained soil and can grow in heavy clay soil. The plant prefers acid, neutral and basic (alkaline) soils and can grow in very acid soil. It can grow in semi-shade (light woodland) or no shade. It requires moist soil.
Of easy cultivation, it succeeds in most soils preferring a good moist well-drained soil on the acid side and partial shade[11, 182]. Grows well in heavy clay soils. Chlorosis can sometimes develop as a result of iron deficiency when the plants are grown in alkaline soils, but in general maples are not fussy as to soil pH. Requires some shelter in the cooler areas of Britain and protection from cold drying winds. Plants are hardy to about -25°c, but spring growth is subject to damage by late frosts. A very ornamental tree, it is a polymorphic species and there are many named varieties[11, 182]. Grows well with rhododendrons. Most maples are bad companion plants, inhibiting the growth of nearby plants[18, 20].
Seed - best sown as soon as it is ripe in a cold frame, it usually germinates in the following spring. Pre-soak stored seed for 24 hours and then stratify for 2 - 4 months at 1 - 8°c. It can be slow to germinate. The seed can be harvested 'green' (when it has fully developed but before it has dried and produced any germination inhibitors) and sown immediately. It should germinate in late winter. If the seed is harvested too soon it will produce very weak plants or no plants at all[80, 113]. When large enough to handle, prick the seedlings out into individual pots and grow them on until they are 20cm or more tall before planting them out in their permanent positions. Layering, which takes about 12 months, is successful with most species in this genus. Cuttings of young shoots in June or July. The cuttings should have 2 - 3 pairs of leaves, plus one pair of buds at the base. Remove a very thin slice of bark at the base of the cutting, rooting is improved if a rooting hormone is used. The rooted cuttings must show new growth during the summer before being potted up otherwise they are unlikely to survive the winter. Only strong-growing cultivars succeed from cuttings, plants of the dissected or variegated cultivars will rarely grow into good plants.
Do you have pest and disease info on this plant? Edit this section!
'Ornatum' - Red Laceleaf Japanese Maple.
Momiji (A. palmatum) shows autumn colours in Kyoto, Japan.
w:Japanese Maple. Some of the material on this page may be from Wikipedia, under the Creative Commons license.
This page was last modified on 19 September 2010, at 13:34.
This page has been accessed 5,210 times.