Quercus serrata Ishii

The Quercus serrata 'Ishii' is a rare Japanese selection of the Dentate Oak in cultivation characterised by a small size and variegated foliage of great elegance. In its youth, Pyramidal developed a more spreading crown, similar to some Japanese maples. This small tree has glossy, toothed green leaves, pale yellow, and cream white, which colour beautifully in autumn before falling. Its bark, which cracks over time, is not without interest. Hardy and undemanding in terms of soil, this refined-looking oak will find its place more easily in small gardens.

The Quercus serrata 'Ishii' is derived from a botanical species called the Korean Oak, Jolcham Oak, or Dentate Oak. Like all oaks, it belongs to the fagaceae family. This species, native to China, Japan, and Korea, was introduced to Europe in 1983 by Charles Sargent. In nature, it grows in deciduous forests, on sometimes rocky soils, up to 2000 m altitude. Preferring warmth but perfectly hardy, this tree adapts to any type of deep and well-drained soil, whether acidic, neutral, or alkaline. However, it does not tolerate severe droughts well and does not like to be moved. It is a monoecious oak, meaning there are male and female individuals. The 'Ishii' selection is female. To obtain acorns, a male or hermaphroditic oak nearby is necessary.

The growth of this 'Ishii' oak is prolonged; it will form a small tree about 4 m tall and 2 m wide on average at the age of 10. Its habit, initially conical in its youth, spreads more over the years. Its bark is grey or reddish-brown and longitudinally fissures with age. Its branches bear clusters of leaves at their ends. Each leaf, lanceolate in shape, narrow, with toothed edges, measures up to 10 cm long. When they emerge in spring, the very young leaves are pubescent and pale orange-brown. As they unfold, they show a beautiful variegation of cream white to pale yellow on a relatively dark green background. The upper surface of the leaves is slightly shiny, while the underside is greyish and somewhat pubescent. In autumn, their colour gradually changes to bronze and then brown. In spring, this oak produces small greenish female flowers grouped in catkins in April-May. Once pollinated, the flowers transform into solitary or paired acorns, which mature in 1 year. Its deep and robust root system, with a taproot type, provides a solid and long-lasting grip in the deep soils it prefers.

The Quercus serrata 'Ishii' deserves a prominent place in the garden, in a not-too-scorching exposure that could damage its beautiful variegated foliage. It should be planted in isolation to showcase it. It naturally fits into a Japanese-style garden in front of a bamboo curtain, accompanied by Nandinas and small conifers (Chamaecyparis Lawsoniana Yellow Spire, Chamaecyparis obtusa Chirimen). To accompany its beautiful foliage from spring to autumn, one can also choose from numerous infinitely refined Asian flowering shrubs, such as Japanese cherry trees and apricots, star magnolias, or autumn camellias, which require the same growing conditions.