Quercus incana W.Bartram

Quercus incana has untapped horticultural potential and deserves a better reputation than it enjoys at the moment. An early introduction to Europe during the 18th century apparently did not prosper, but a reintroduction in the 1990s is now faring better, after an uneven start. In the wild it is an attractive tree of low stature and distinctive grey-backed leaves, distributed along the Atlantic Coastal Plan in southeastern USA, from southeast Virginia to central Florida and west to Texas.

The main attraction of this species lies in its foliage: lanceolate, entire leaves, pale green above and grey tomentose below, which emerge and senesce in appealing shades of red. As Grimshaw and Bayton observed in New Trees (2009): ‘the grey pubescence gives interesting colour effects as the bronze flush of new growth or the red autumn tints develop below it’.

These same authors, however, did not hold high hopes for its horticultural success in northern Europe, remarking that the specimens they saw in England had ‘the appearance of being there against their wishes.’ Plants at Chevithorne Barton, Devon, were doing particularly poorly, lacking distinct leaders and forming ‘a tangled top that looks more like an Elaeagnus than an oak’. In the intervening years since the publication of New Trees, however, trees of this species in cultivation have smartened up their act, forming young specimens of elegant, narrow habit. The best in the UK is to be found in the Sir Harold Hillier Gardens, where a specimen in the garden area BL110, one of two trees grown from seed of wild origin collected in Bienville Co., Louisiana in 1993, had reached 6.4 m × 8 cm in 2021; it is in a sunny site on sandy soil (The Tree Register 2025; pers. obs. RC 2024). The other tree of the same accession, in BH800, had caught Grimshaw and Bayton’s eyes as the most satisfactory representative they had seen of this species, measuring 4.2 m in 2008, growing in similar conditions. A tree of the same origin is growing at Westonbirt, in a more open location, and has not grown as tall (or as fast), standing at around 2 m in 2025 and looking somewhat stunted (D. Crowley, pers. comm. 2025). It thus appears that in cultivation in the UK it appreciates the companionship and shelter of others. Several other specimens of Q. incana are recorded by The Tree Register (2025) in the United Kingdom, between 5 and 6.5 m tall, with the current champion growing at Chevithorne Barton and leading the field at 6.5 m × 14 cm, measured in 2017.

In sunnier climes, where it enjoys the hot summers it seems to still crave in Britain, it has performed even better. At Arboretum des Pouyouleix, south-central France, it has prospered: two specimens grown from seed collected by Thierry Lamant in Van Zandt Co., Texas, in 2003, have formed fine trees of pyramidal outline and sound structure, already reaching 6 m in 2019. On these trees, the leaves of the second flush often bear one or two aristate teeth towards the apex (B. Chassé, pers. comm. 2025; pers. obs. AJC 2019). At Iturraran Botanic Garden, it has surprised with healthy growth and habit, despite the damp conditions there (1600 mm rain per year); it is possible that good drainage, made possible by the steep bank it has been planted on, allows it to thrive in the humid conditions it is not supposed to enjoy (Haddock 2024). At the Arboretum des Grandes Bruyères, near Orléans, which holds a French National Collection of American Oaks, it is one of the owner’s favourite New World oaks, with attractive foliage from spring through autumn (Brigitte de la Rochefoucauld 2011).

Several trees were trialled at Starhill Forest Arboretum, Illinois. The first was planted as an 8 year-old sapling in 1998, sourced from South Carolina. None have survived, indicating that the species is not hardy in the Zone 6 climate there. However, given probable climate change, a plant from the northern limit of its range may stand a better chance in future (A. McKean, pers. comm. 2025).

It seems to have been introduced relatively early, among the first North American oaks to be cultivated in Britain, but with scant success and apparently dropping out of cultivation entirely before being reintroduced at the end of the 20th century. Some uncertainty is caused by the fact that it was known under different names before Quercus incana became universally accepted as the correct name. What is probably this species was recorded in Hortus Kewensis (Aiton 1789) as Q. phellos var. sericea, cultivated in 1724, according to a ‘Catalogue of trees sold by Robert Furber’ published that year. The second edition of Hortus Kewensis (Aiton 1811) lists the taxon as Q. cinerea and gives the date of introduction as ‘before 1789.’ Loudon (1838) provided a detailed description of the species (as Q. phellos var. cinereus), but does not mention any specimens in cultivation. Elwes and Henry (1906–1913) suggested it may be a variety of Q. phellos and concluded that it is ‘extremely rare in cultivation,’ reporting having seen only one specimen, a healthy tree at Kew Gardens reaching about 9 m, which would make it about 1.5 m taller than the largest trees in cultivation today. This tree has not survived, and the species is not currently in the Kew collection. Bean (1976) stated the species was probably not in cultivation in Britain.

It was apparently first described by Mark Catesby in The Natural History of Carolina, Florida and the Bahama Islands (1743), where he gives it the common name Highland Willow Oak. His description, however, fails to mention the grey leaf undersides, the most distinctive feature of the species. It describes instead its small stature, pale green leaves, and small acorns, and the fact that it grows on dry, poor soil. Linnaeus (1753) cited Catesby when describing his Q. phellos var. γ, which Lamarck (1785) later called var. brevifolia. Michaux in 1801 raised it to species status as Q. cinerea, also citing Catesby’s publication, and it was long known by this name (e.g. Elwes & Henry 1913). However, Bartram had described it as a species in his Travels through North & South Carolina, Georgia, East & West Florida (1791), a decade before Michaux, with a brief Latin description that included mention of the grey tomentum on the leaf undersides (foliis … subtus incanis). Bartram’s name has been generally accepted as the name for this species, and it was neotypified in 2009 by Reveal, who designated Catesby’s illustration as the type.

The epithet derives from Latin meaning ‘grey’, but specifically the grey of hair that turns that colour with age. In botanical terminology, it is thus used to refer to grey pubescence. It can be traced to canere, which means ‘to become white’, and a descendant of this term is found in Spanish, where canas are hairs that have turned grey with age or stress. The epithet chosen by Michaux, cinerea, also means grey, but in reference to the colour of cold ashes. It derives from Latin cinis (= ‘ashes’) (Eckel 2021; wiktionary.org 2025). The common name, Bluejack Oak, refers to the blue-green leaf colour and its affinity to Blackjack Oak, another small, sometimes scrubby oak, with similar bark, also found on well-drained sandy soils in eastern USA.