Norway Maple ‘Crimson King’ · Acer platanoides ‘Crimson King’

The defining character of 'Crimson King' is its dark crimson-purple foliage, which holds saturated tone from leaf-out in April through late summer before warming to red and bronze at leaf fall. Leaves are broad, five-lobed, and palmate, carrying the same morphology as the green-leaved species but with the dark pigment that distinguishes this cultivar. In Portuguese cultivation the tree reaches 10 to 15 metres in height and 6 to 10 metres in spread at maturity, with a rounded crown on a single clean stem.

Performance varies sharply across the Portuguese climate gradient. In the humid Minho and Douro, in cooler microclimates of Greater Porto, and across the Beiras at altitude, the dark foliage holds colour reliably and the tree establishes on the granite and schist soils of Diaplant's Amarante base. In urban Lisbon the cultivar performs as a framework tree (árvore de estrutura) on irrigated sites with reasonable soil depth. In the interior Alentejo and the inland Algarve, summer heat above 38 degrees C scorches the dark leaf surface and stresses young bark, and Celtis australis or Fraxinus angustifolia are the more defensible specification.

The cultivar earns its place where deep purple is required as a colour anchor rather than a feature accent: avenue alignment (arruamento) for visual rhythm against pale stone façades, public square (praça) planting where the dark crown contrasts with lighter-leaved species, and large garden schemes at the scale of mature Tilia or Platanus. Yellow corymbs in April provide a brief two-week contrast against the emerging purple foliage.

Root behaviour is shallow and laterally aggressive, which precludes specification within two to three metres of finished paving or shallow utilities. The species is susceptible to Verticillium wilt and to bark sunscald on young trunks in exposed positions, both pressures that intensify in the warmer Portuguese zones; staggered planting reduces single-pathogen failure risk. Maintenance is otherwise low: formative pruning in the first three years, light crown work thereafter, and irrigation through the first two summers on all but the wettest sites.