Quercus phellos L.

Willow Oak is an outstanding landscape tree, notable for the fine texture of its foliage in summer and attractive gold colour in autumn. It also has advantageous characteristics that endear it to the nursery trade (swift growth, tolerance of adverse conditions, and ease of transplant). It is probably the best known of the few oaks with leaves with entire margins, a group that Sternberg (2004) refers to as ‘no-lobers’ (Shingle Oak, Quercus imbricaria, would be the other member of the category that is found in the US, and one needs to venture south to Mexico or across to southeast Asia to find the others). True Willow Oak always has entire margins: though some sources such as The Hillier Manual (Edwards & Marshall 2019) assert that the leaves of young trees are often lobed, any lobing is usually interpreted as a sign of hybridisation with another lobed Section Lobatae oak.

Quercus phellos grows in the low wet borders of swamps and streams and rich sandy uplands, and is distributed from Staten Island, New York, to northeastern Florida, through the Gulf states to the valley of the Sabine River in Texas, and through Arkansas to southeastern Missouri. In the states on the Atlantic coast, it is usually confined to the low maritime plain, though it does not grow close to the coast (Sargent 1895). Its quality and growth rate are affected by soil characteristics: it is rarely found on upland sites, but does occur on flats on old terraces where soil is underlaid with hardpan that slows drainage; in these sites, it is of poor commercial quality (Miller & Lamb 1985).

Quercus phellos likes moisture and full sun and does best in acid soil (Sternberg 2004). Some authors, including The Hillier Manual (Edwards & Marshall 2019), go as far as to say it requires a lime-free soil, but that seems an exaggeration, given its popularity as a street tree in the US. It is widely used there in urban plantings in the south, but also in New York, where it is one of the most planted oaks. For Dirr (2009), it is the best oak for overall texture and form, making a splendid avenue, street or boulevard tree, and also excelling in large areas such as commercial establishments, golf courses and parks. It dominates landscaping in the Southeast, valued for its fine texture, ease of transplanting, and full canopy, even as a young tree. It has been admired in urban plantings from Spartanburg, South Carolina and Chapel Hill, North Carolina (Dirr 2009) to New York City, where Piet Oudolf chose it to accompany Q. bicolor as the protagonists of his design of Battery Park (Cameron 2022).

Across the Atlantic, where it arrived in the late 17th century, Loudon (1838) was not seduced by its charms. He described it as the least beautiful of North American oaks, ‘its foliage being light in colour, thinly spread over the tree, and dying off, in autumn, with very little change,’ but he was writing at a time when northwestern Europe was much colder than it is today, and it is possible that conditions in that region have only tipped in Willow Oak’s favour in the relatively recent past. Most contemporary authors seem to concur with Hugh Johnson (2010), for whom it is a ‘superb ornamental’, and it has been relatively widely planted in recent years. Willow Oak leaves do change colour in autumn, turning yellow or bronze-yellow to bronze-orange (in some selections, it turns red, see below). A salient characteristic is that leaves do not all turn at the same time, creating a pleasing mottled look of green and yellow early in the autumnal season. In spring, the foliage is also notable, emerging in very narrow, tentacle-like leaves of dark purple.

Like other section Lobatae oaks, Quercus phellos is susceptible to oak wilt (Bretziella fagacearum) in the US, and damage from Gypsy moth (Lymantria dispar). Other foliage problems are pine-oak rusts (Cromartium sp.) and leaf blister (Taphrina caerulescens), which affect red oaks more than white oaks (Sternberg 2004). According to Dirr and Warren (2019), however, Willow Oak has so far ‘weathered the hosts of insects and diseases that negatively impact the genus’. They recommend it for street use but alert that it should be given room to spread with age: they suggest 10 m between trees, for in fifteen years branches will be touching.

In the US, the current champion tree and the runner-up, according to the National Champion Tree Program (2025), both grow in Virginia: the tallest in Matthews (33.5 m × 268 cm dbh) and the thickest in Northampton (32.3 m × 269 cm), both measured in 2023. Trees in cultivation are significantly smaller. In the UK, the current champion for height grows at Kew, planted in 1906 and reaching 26 m × 92 cm in 2022. A taller tree was recorded by Elwes and Henry in 1905, growing at Whitton Place, Hounslow, about 31 m × 119 cm, its trunk attacked by fungus and decaying rapidly (Elwes & Henry 1910). The current champion for girth is also at Kew, a modest 20.5 m × 106 cm, though several trees with larger trunk diameters, since lost, are recorded in the Tree Register, the largest 131 cm across (The Tree Register 2025). In Europe the largest trees are taller than in the UK, though thinner in diameter, both champions growing in the Netherlands and measured in 2025: the tallest in a private garden in Helmond, North Brabant (31.8 m × 93 cm) and the thickest at Julianapark, Limburg (25.4 m × 97 cm) (Monumental Trees 2025).

Quercus phellos is not widely planted in the Southern Hemisphere, though curiously it is found in Uruguay, thanks mainly to a specimen planted in Arboretum Lussich near the seaside resort Punta del Este, which evidently has been the source of seed for several specimens that can be found nearby as street trees or in private gardens, and also in Montevideo. Some of this progeny are evident hybrids with lobed red oaks, resulting in narrow leaves with aristate lobes, reminiscent of the Acutifoliae series of Mexican oaks (pers. obs. RC).

As an oak tree with narrow, entire leaves, it captured the attention of 17th-century Europeans. It first appears in a catalogue of plants sent to England from Virginia by John Banister, included among several oaks and identified as Lini aut Salicis folius (‘flax- or willow-leaved’). It was first described in 1704 by Ray, who was not sure whether it was an oak (what is now known as subgenus Quercus) or a holly-oak (today’s section Ilex), and called it Quercus, an potius Ilex Marilandica folio longo angusto Salicis´(‘Oak or more likely holly-oak from Maryland with long narrow leaves like a willow’). Catesby illustrated it and described it in 1730, under the common name Willow Oak, citing Ray’s polynomial. When Linnaeus published it in 1753, however, he used the quite inappropriate nomen triviale ‘Phellos’, which derives from the ancient Greek φελλός (phellós) and means ‘cork’, especially the cork in a fishing net, and is also the name for Cork Oak (Quercus suber). There is nothing corky about Willow Oak’s bark, as it is distinctively smooth or lightly fissured when young, though it becomes thicker and fissured with age. By 1723 the species was growing in Thomas Fairchild’s garden, as reported by W.T. Aiton in 1813 – not by Catesby, as Loudon 1838 and Elwes and Henry (1913) would have it. In 1724 it was being offered for sale by Robert Furber (Aiton 1789).