Quercus phellos willow oak

Willow Oak is an unusual species that, honestly, does not look like an oak at first glance. Its deciduous leaves are narrow to linear‑lanceolate, typically 6–12 cm long and only 1–2 cm wide, with entire margins and a finely pointed tip; in shape they closely resemble willow leaves, hence its common name. The upper surface is bright green until early summer, later turning dark green and glossy, while the underside is paler, glabrous or only occasionally minute. In autumn the foliage colours into striking shades of yellow to yellow‑brown, sometimes with a bronze tint, and often remains on the tree longer than in most other oaks.

The tree develops a straight trunk and a regular, broadly conical crown in young age with a light, airy structure, formed by slender branches that are initially ascending and later spread more horizontally; in younger specimens the branching can recall that of Lebanon cedars. With maturity, the crown becomes more rounded, forming a regular canopy of broadly oval to rounded shape. The bark of young trees is smooth and grey‑brown, darkening with age and developing shallow longitudinal fissures, without the deep, coarse ridges typical of many other North American oaks. The current‑season shoots are slender, olive‑brown to grey, with small, ovoid, inconspicuous buds. From late summer onwards, small acorns ripen and often persist on the branches after leaf fall, extending the availability of food for birds and mammals.

In the landscape, willow oak is valued primarily as an ornamental specimen and as a tree for large parks, riverside promenades and formal avenues. Its narrow, glossy leaves and late, decorative autumn colour are effective both as a solitary feature and in groups. It is particularly well suited as a dominant element near water bodies, on expansive lawns in front of historic estates, or in arboreta, where its stately habit can be fully appreciated; in smaller gardens it is appropriate only as a carefully chosen specimen tree. In Britain it has gained popularity as a collection and park tree – notable specimens grow at Kew Gardens, near Syon House, at estates such as Powis Castle, and in parks in Hastings and Surrey – demonstrating how impressively it can grow and perform in a European climate.

Willow oak grows rapidly: once established, it can make 50 cm or more per year, and in maturity, which may take up to 50 years, it can readily reach heights and spreads of up to 30 metres. It is undemanding in cultivation and, apart from careful site selection and firm staking of standard trees during the first three to four years, requires little attention. It prefers full sun and deep, fertile soil, yet it is remarkably adaptable: it tolerates both drier sites thanks to its deep root system and temporary flooding, and copes well with hot summers as well as Central European winters. Its roots are deep and non‑aggressive, so they generally pose no risk near buildings or paved areas; nevertheless, the tree develops a broader root flare, and before the roots descend more deeply, it forms several short but strong structural roots radiating around the trunk – something that should be taken into account. It does not tolerate heavy applications of de‑icing road salt. Its frost hardiness is commonly given as down to −29 °C (USDA zone 5), with reports of individual trees surviving extremes of around −32 °C in Cincinnati, USA.

Last update 16-02-2026