Quercus robur Concordia - English Oak

Quercus robur 'Concordia' is a very beautiful cultivar of the pedunculate oak, with moderate growth and bright yellow foliage until summer. Extremely bright and easily maintained through pruning, this contrasting tree will find its place in a medium to small-sized garden, in combination with green or purple foliage. Just like its big brother the common oak, it is perfectly adapted to most of our temperate regions. It only needs light, slightly calcareous, fertile, and fresh soil to thrive.

The pedunculate oak, also known as the common oak, English oak, male oak, or gravelin, belongs to the Fagaceae family. It is native to a large part of temperate Europe. It appreciates sub-oceanic to oceanic climates, or continental climates without excess and relatively humid. This tree is very common in our lowland plains and hills, but rare in the Southern Alps and Mediterranean region, which are too dry and too hot. In its natural habitat, it can reach up to 50m (164ft) in height and have a spread of 25 to 30m (82 to 98ft 5in), while its trunk can measure up to 2m (6ft 7in) in diameter. With a fairly exceptional longevity, this oak can live up to 2000 years according to some estimates.

The 'Concordia' cultivar will reach an average maturity height of 7m (23ft) with a spread of 5-6m. The growth of this oak is moderately fast. Its habit is erect during its early years, with the canopy gradually expanding to adopt a more rounded shape. The trunk, quite short, is initially green and smooth, then becomes grey, thick, and deeply fissured. Its young branches are glabrous and grey in colour, shiny. The foliage, late deciduous, is composed of alternate, soft, obovate leaves that can reach 5 to 15cm (2 to 5.9in) in length and 3 to 8cm (1.2 to 3.1in) in width. Each leaf is divided into 5 to 7 pairs of asymmetrical rounded lobes, separated by relatively deep sinuses. The base of the lamina is narrow and has 2 small lobes. The colour of the lamina is acidic green when it buds, becoming more yellow with increasing light intensity, with the lower surface being paler. The leaves turn brown quite late in autumn and remain attached to the branches before falling. The flowering of this oak occurs in April-May, shortly after the appearance of the foliage, on the annual shoots. The female flowers are placed in a cupule carried by a long peduncle: this distinctive characteristic is the origin of the species name, pedunculata. The male inflorescences are elongated, pendulous catkins, tinged with yellow. They are produced on older branches. The female flowers give way to ovoid and elongated acorns, measuring 1.5 to 3cm (0.6 to 1.2in) in length. They are often grouped in pairs or threes and attached to a long peduncle. A cupule covered with scales covers one-third of the acorn. The color changes from green to brown when ripe, in September and October. The root system of this tree is deep and powerful, with both a taproot and extensive lateral roots, providing a solid and durable anchor in deep and compact soils.

The 'Concordia' oak, a contrasting tree, will become one of the main features of a natural or even contemporary garden large enough to accommodate it. In spring, a graceful ballet of young acidic green leaves takes place, turning to golden yellow as they unfold, a shade to be associated with the purple of hazelnut trees or the 'Purpurascens' variety, as well as the blue flowers of Sophora davidii or buddleias. It can be planted individually or in a grove. It also has the advantage of providing pleasant shade, which will reflect light in winter, and producing abundant leaf litter, favourable for the growth of certain plants that germinate under its cover. Its fruits, sometimes produced in abundance, feed small animals such as squirrels and jays.