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Acer palmatum 'Seiryû'
Seiryu Japanese Maple
Japan, Korea, and China (species); 'Seiryû' is a Japanese horticultural selection
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Overview
Acer palmatum 'Seiryû' is a deciduous tree reaching 10–15 feet (3–4.5 m) tall with a spread of 8–12 feet (2.4–3.7 m), with an upright vase-shaped to broadly upright habit. It belongs to the dissectum group of A. palmatum, with deeply dissected seven-lobed leaves 2–4 inches (5–10 cm) wide; the sinuses are cut nearly to the center of the leaf and the lobes are further incised, producing a lacy, thread-like leaf texture. Leaf color is medium to bright green through spring and summer, shifting to orange through red-crimson in October with a display lasting 2–3 weeks. Most dissectum A. palmatum cultivars such as 'Crimson Queen' and 'Red Dragon' have a weeping, cascading form and are typically grafted onto a standard to achieve height; 'Seiryû' grows upright on its own roots and reaches its mature height of 10–15 feet (3–4.5 m) without a grafted understock. Small dark red to purple flowers appear in pendant clusters in April and May. Samaras 0.75–1 inch (2–2.5 cm) long ripen in September and October. Growth rate is moderate at 6–10 inches (15–25 cm) per year. Limitation: the finely dissected leaf segments scorch along margins under summer temperatures sustained above 85°F (29°C), drought, or exposed windy sites, where the narrow lobe tips desiccate before the rest of the leaf.
Native Range
Acer palmatum is native to Japan, Korea, and China, growing in mixed broadleaf forests at low to middle elevations. The 'Seiryû' cultivar is a horticultural selection developed in Japan and does not occur in wild populations.Suggested Uses
Used as a specimen in Japanese-style gardens, woodland gardens, and mixed shrub borders where a dissected-foliage A. palmatum with a vertical rather than cascading form is desired, at 10–12 foot (3–3.7 m) spacing. The lacy leaf texture, upright habit, and orange to red-crimson fall color supply multi-season interest. Hot-summer climates, exposed windy sites, alkaline soils, and sites with restricted moisture are unsuitable.How to Identify
Appearance
Size & Dimensions
Height10' - 15'
Width/Spread8' - 12'
Reaches mature size in approximately 15 years
Bloom Information
Small dark red to purple flowers 0.3–0.4 inch (8–10 mm) across appear in pendant clusters in April and May as new leaves emerge. Samaras 0.75–1 inch (2–2.5 cm) long ripen in September and October.Detailed Descriptions
Flower Description
dark red to purple; small pendant clustersFoliage Description
medium to bright green through spring and summer; orange to red-crimson in fall; deeply dissected seven-lobed leaves with sinuses cut nearly to the center and lobes further incised, 2-4 inches (5-10 cm) wideGrowing Conditions
Sun Requirements
Requires 3-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Site in partial shade to full sun with 3–8 hours of direct sun per day in moist, well-drained, humus-rich soil with a pH of 5.5–7.0. Full sun siting is only suitable in cool-summer climates. Water weekly during the first two growing seasons. Established plants tolerate dry intervals of 7–10 days before the dissected leaf segments show scorch along margins. Summer temperatures sustained above 85°F (29°C) cause marginal scorch on the narrow leaf lobes. Hardy in USDA zones 5–9 with reliable performance in the Pacific Northwest, upper Midwest, and northeastern United States. Grown on its own roots, this cultivar does not require monitoring of a graft union or removal of rootstock suckers. Routine fertilization is not required in humus-rich soils.Pruning
Routine pruning is not required. The upright vase-shaped form develops naturally without staking or training. Corrective pruning can be done in late spring to early summer (May and June) after leaf-out. Dead or crossing branches can be removed at any time. The dominant upright leaders should be retained to hold the vertical habit. Late summer and fall pruning increase the risk of dieback at cut ends.Pruning Schedule
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late spring