Japanese Maple ‘Seiryu’ · Acer palmatum ‘Seiryu’

'Seiryu' is the only cultivar within the Dissectum group of Acer palmatum to hold an upright habit. Every other laceleaf maple develops a weeping, mound-forming shape with branches arching toward the ground; this one forms a small upright tree with a vertical, lightly rounded crown reaching 3 to 4.5 m in height and 2 to 3 m in spread at maturity. The Japanese name translates as "green dragon", a reference to the ascending silhouette above the finely cut foliage.

The deciduous foliage is deeply dissected into narrow filaments, a clear luminous green from leaf-out through late summer. Autumn coloration moves through yellow and orange with red highlights, a more varied transition than the monochrome red of the purple-leaved dissectums. The colour shift settles between mid-October and late November in conditions of the Atlantic strip and the cooler Mediterranean coast.

Growth vigour is unusually strong for a laceleaf maple, closer to a species-form Acer palmatum than to a weeping dissectum. This removes the need for high-stem grafting and the annual crown training that pendulous dissectums require; the framework organises itself, with only sanitary pruning in late winter.

Site preferences match the rest of the palmatum group: cool, free-draining, slightly acidic to neutral soil, with half-shade obligatory across the Mediterranean coastal strip (Levante), the Balearics and the semi-arid southeast, where summer sun rapidly scorches the fine lamina. Performance is reliable in the Atlantic strip (Galicia, Asturias, the Basque Country), in the Empordà interior, in sheltered Catalan coastal sites with assured shade, and at altitude in the Sierra de Guadarrama foothills. Hardiness is sound to approximately -15 °C, with reliable establishment across the continental interior (meseta) on protected sites. Drought tolerance is limited: supplementary irrigation through the first three summers is standard, and a maintenance cycle is advisable through extended summer drought thereafter. Not within the known Xylella fastidiosa host range of present regulatory concern in Spain.

Use as a focal specimen in walled patios, courtyards (patios cordobeses), shaded garden corners, or as a large container subject on sheltered terraces. It substitutes for a weeping dissectum wherever the project specification (pliego de condiciones) calls for a vertical silhouette rather than a cascade, or where the horizontal spread of a high-grafted pendulous cultivar exceeds the available footprint.