Japanese Maple ‘Seiryu’ · Acer palmatum ‘Seiryu’

'Seiryu' is the only cultivar within the Dissectum group of Acer palmatum that holds an upright habit. Every other laceleaf maple develops a weeping, mound-forming shape with branches arching towards 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 means "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 shifts through yellow and orange with red highlights, a more varied transition than the monochrome red of the purple-leaved dissectums. The colour break settles between mid-October and late November under Atlantic Portuguese conditions.

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

Site preferences match the rest of the palmatum group: cool, free-draining, slightly acidic to neutral soil, with half-shade obligatory in the central Algarve and the inland Alentejo, where summer sun rapidly scorches the fine lamina. The cultivar performs reliably in sheltered Greater Lisbon (Sintra, Cascais), across Greater Porto, along the Silver Coast, and in walled gardens of the central Algarve where afternoon shade is assured. Drought tolerance is limited: supplementary irrigation through the first three summers is standard practice, and a maintenance irrigation cycle in extended summer drought is advisable thereafter.

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