Red Maple · Acer rubrum

Reaching 18 to 25 m at maturity with a rounded to upright crown and 9 to 15 m spread, arce rojo americano is among the fastest-growing maples available to specifiers, putting on reliable annual extension once established. The autumn display is the species' defining trait: foliage turns vivid scarlet, sometimes orange, in a more saturated register than Acer platanoides or Acer pseudoplatanus achieve in Iberian conditions. Small clusters of red flowers open on bare wood in March and April, before leaf-out, giving a short but legible early-season interest.

The specification constraint that decides everything is soil chemistry. Acer rubrum is calcifuge, and on the calcareous and alkaline substrates that cover most of the peninsula, the meseta, the valle del Ebro, the Levante, the sureste, and much of Andalucía, foliage develops severe manganese and iron chlorosis that no irrigation regime corrects. The species specifies cleanly only on acidic ground: Galicia and the cornisa cantábrica, the granitic central sierras (parts of Gredos, Guadarrama, Sierra de Gata), and the Sierra Morena silícea.

Where the project sits outside these acidic zones, container culture in an acidic substrate is the practical workaround; the species does not adapt to high-pH open ground at landscape scale. On suitable sites it tolerates seasonally wet conditions to an unusual degree, performing where many ornamental species fail, which makes it a strong candidate for low-lying parkland, retention-basin margins, and ground subject to winter waterlogging.

Hardy to roughly minus 35 °C at the cold end of its range, the species carries no climatic concern across Spanish winters; the meseta's late spring frosts are well within its tolerance. Roots run shallow and dense, with surface-mat behaviour that excludes underplanting and warrants a 4 to 5 m setback from paving and services. Specify into parks, campus grounds, and large private gardens on acidic ground; in calcareous Spain, reach instead for Acer campestre, Celtis australis, or Fraxinus angustifolia.