Acer palmatum ‘Ō-kagami’

Japanese Maple

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Acer palmatum ‘Ō-kagami’ has intense-red leaves in spring that are large turn to a glossy, green-blue in summer, and fiery scarlet in autumn. This maple is a robust, upright grower. It prefers moist, well-drained soils, but may suffer from leaf scorch due to excess sun, wind, and drought. It is cold hardy and great for bonsai. Acer palmatum is deciduous and native to Japan, Korea, China, eastern Mongolia, and southeast Russia.

Synonyms: Acer palmatum 'Okagami', Acer palmatum 'O-kagami'

Uses: Small garden

GROWTH HABIT

Winter Foliage: Deciduous


Height: 4.0m

Width: 3.0m
Estimated 10 year height and width

GROWING CONDITIONS

Soil: Clay, Sandy

Position: Full sun, Partial shade

Tolerates: Heavy Frosts, Light frosts

SEASONAL COLOUR

Summer
Autumn
Winter
Spring
Foliage
Fruit
Stem
Flower

Acer palmatum ‘Ō-kagami’ stock information

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Explanation of terms

Globular crowns have a rounded form with vertical and horizontal dimensions being approximately equal. Ovoid crowns are somewhat elliptic, broader at the base than they are at the top, with the vertical axis greatly exceeding the horizontal axis. Obovoid crowns are also somewhat elliptic, with the vertical axis greatly exceeding the horizontal axis but are broader in the upper part of the crown. Conical crowns are approximately triangular in their outline and are broadest at their base. Columnar crowns have a vertical axis that greatly exceeds the horizontal axis but the proportions of the upper and lower crown are similar. Irregular crowns have an asymmetrical and uneven outline. Weeping crowns have strongly pendulous branches. Vase crowns are much broader in the upper crown, which is often relatively flat rather than rounded.

Information sourced from the Tree Species Selection for Green Infrastructure guide produced by the Trees & Design Action Group. Find the guide here: https://www.tdag.org.uk/tree-species-selection-for-green-infrastructure.html

Healthy crowns differ in their density as a function of leaf and branching characteristics. Three categories are used: dense, moderate and open. In some cases, it has been possible to underpin these categories with leaf area index (LAI: leaf area per unit ground area (m2 m-2) data. Dense crowns typically have a LAI of >6m2 m-2, moderate crowns 3-6m2 m-2 and open crowns <3m2 m-2.

Information sourced from the Tree Species Selection for Green Infrastructure guide produced by the Trees & Design Action Group. Find the guide here: https://www.tdag.org.uk/tree-species-selection-for-green-infrastructure.html

The four-level scale, tolerant to drought; moderately tolerant to drought; moderately sensitive to drought; and sensitive to drought, makes use of a number of sources of information. The Niinemets and Valladares (2006) scale integrates a range of climatic factors and the physiological potential to survive with <50% of foliage damage or dieback to create a continuous five-level scale (see table below).

Scale used by Niinemets and Valladares (2006) to rank 806 temperate woody species according to their drought tolerance. Trees were allocated a ranking based on their ability to survive on a site, with <50% foliage damage and dieback. P : PET is the ratio of precipitation to potential evapotranspiration.

Scale ranking Annual precipitation (mm) Distribution of precipitation (coefficient of variation) P : PET ratio Soil water potential (MPa) Duration of dry period
1: Very tolerant >600 Minimal >3.0 > -0.3 A few days
2: Intolerant 500-600 <10% 1.5 : 3 -0.3 to -0.8 A few weeks
3: Moderately tolerant 400-500 10-15% 0.8-1.5 -0.8 to -1.5 Up to a month
4: Tolerant 300-400 20-25% 0.5 : 0.8 -1.5 to -3 2-3 months
5: Very tolerant <300 >25% <0.5 < -3 More than 3 months

Information sourced from the Tree Species Selection for Green Infrastructure guide produced by the Trees & Design Action Group. Find the guide here: https://www.tdag.org.uk/tree-species-selection-for-green-infrastructure.html

Most temperate deciduous trees can cope with several weeks, waterlogging during the period of winter dormancy as metabolic activity is minimal. However, waterlogging during active growth is more serious because roots are more active and require aerobic soils. In general, the more active the growth, the more rapidly the effects of waterlogging can be seen. Factors such as the water oxygenation status and temperature will also affect how acutely waterlogging stress develops so there can be a great deal of variation around how trees experience waterlogging stress.

For this scale, tolerant species can survive consistent waterlogging for the duration of the growing season. Moderately tolerant species can survive consistent waterlogging for approximately one month during the growing season. Moderately sensitive species are only likely to survive if the waterlogging event is less than two weeks during the growing season and sensitive species are only likely to survive if the waterlogging event is less than a few days during the growing season. However, it is important to note that as this scale relates to the likely time-course to tree mortality, symptoms of waterlogging (and associated dysfunction) will be apparent within a shorter period of time.

Information sourced from the Tree Species Selection for Green Infrastructure guide produced by the Trees & Design Action Group. Find the guide here: https://www.tdag.org.uk/tree-species-selection-for-green-infrastructure.html