Quercus calophylla Schltdl. & Cham.

This is one of the more attractive Mexican oaks, as its epithet testifies. Bob Berry, probably the greatest collector and grower of Mexican oaks, said it was his favourite tree (Chassé 2011; Tupper 2016). The eponymous beautiful leaves emerge covered in orange tomentum that turns yellowish brown or tawny before becoming dark glossy green above with striking white undersides. These undersides were responsible for the name it was previously known as, Q. candicans, but it turns out that the type specimen described under this name was not even an oak.

It is widely distributed in Mexico, where it is found growing as a large spreading tree on steep mountain slopes and hills, in humid forests, often on limestone soils, though in Michoacán it grows on volcanic soils of acid to neutral pH. A feature of this species is that the same plant can appear to bear differently shaped sorts of leaves: young leaves can have conspicuously toothed margins, and as they mature the margin expands to absorb the teeth, so that mature leaves have practically entire margins with short bristles prolonging each nerve. The upper surface, a lustrous dark green, is slightly bullate or blistered; the midrib is slightly impressed above and prominent below, while secondary venation is clearly reticulated on both surfaces, but only prominent below. The handsome white undersides are the result of a dense tomentum that can turn yellowish as it matures. The foliage is particularly eye-catching when a breeze ruffles it, the leaves flipping from cream to dark green. Depending on climatic conditions, it can be fully or semi-deciduous, and the leaves usually turn red before falling. Also attractive is the bark in young trees, which is pale grey and pachydermatous, or reminiscent of elephant skin, similar to Q. mexicana; the bark becomes darker and fissured with age (le Hardÿ de Beaulieu & Lamant 2010).

Quercus calophylla appears to have been first introduced to cultivation by Bob Berry at Hackfalls Arboretum, New Zealand, from seed collected in 1984 in Michoacán, Mexico. At the San Francisco Botanical Garden there are several specimens from a 1986 collection by Dennis Breedlove (see below). In the UK, the earliest record is that of the 1991 expedition to Mexico by Compton, d’Arcy and Rix (CDR 1109), which prospered for a time at Chevithorne Barton and survives at Tregrehan as the UK Champion.

At Chevithorne Barton the two trees from CDR 1109 were ‘probably the stars of the collection,’ growing to form handsome upright trees reaching 11 m and apparently en route to greater heights. Michael Heathcoat Amory ominously warned that they were marginal in the climate there and his boast in 2009 that they had not suffered any frost damage for the last six years proved premature: the trees were badly damaged in the very cold winter of 2010–2011 and the bark split, and though they both produced vigorous shoots from the base, one was dead and one badly damaged by 2012 (Heathcoat Amory 2009; pers. obs.). Other trees still survive in the collection, including one from PCH 162, which measured 9 × 15 cm in 2017 (The Tree Register 2023). The Hillier Manual (Edwards & Marshall 2019) warns that leaves, young shoots, and the beautiful bark can suffer frost damage, but several other UK collections hold this species, including Penrice Castle in southern Wales (4 m in 2021), Chyverton, Cornwall (9 m × 24 cm in 2016, despite having had its top broken in 2006), and Tregrehan, Cornwall, where a beautifully straight young tree planted in 1994 has reached 24 m × 40 cm in 2022 (The Tree Register 2025).

It grows in several gardens in Europe, but apparently at a slower pace: at Arboretum des Pouyouleix, central France, a specimen from seed collected in Puebla in 2006 and planted in 2008 had reached 4.5 m × 10 cm dbh in 2021, and has fruited since 2019 (B. Chassé, pers. comm.); at Arboretum de la Bergerette, south-central France, a tree planted in 2008 was 2.6 m × 3 cm in 2016 (S. Haddock, pers. comm.). In the benign conditions of Iturraran Botanic Garden, northeast Spain, a tree had reached 15 m in 2019 (pers. obs. AJC). At Trompenburg Gardens and Arboretum in Rotterdam, however, two trees were damaged by –10°C frost in February 2018. They were grown from seed collected in Puebla in 2009 at 1,940 m elevation and had overwintered outdoors in open ground since 2013, growing vigorously and producing heavy foliage that required staking. They reached 4 m in 2018, with attractive bark subsequently cracked by frost, and by 2022 the trees were leafless with no new growth in spring (G. Fortgens, pers. comm. 2023).

In the US it grows in Aiken, South Carolina, where it was unharmed by the severe –7°C frost in 2017 (Russell 2017). At the San Francisco Botanical Garden, there are four trees accessioned in 1987, from seed collected by Dennis Breedlove in Jalisco, Mexico, at 2130 m elevation in 1986; one of them, ‘a particularly beautiful specimen’ about 10 m tall in 2004, caught the eye of John Grimshaw (2009). A tree from the same Breedlove collection is still standing at the Shields Oak Grove at UC Davis Arboretum, despite substantial dieback due to recent droughts there (E. Griswold. pers. comm. 2023).

Quercus calophylla seems to have done best in cultivation in the Southern Hemisphere. At Grigadale Arboretum, Argentina, a tree from seed collected in Puebla in 2009 was planted in 2014 and reached 2.6 m × 7 cm dbh in 2018 and 6.7 m in 2022, forming a broadly pyramidal and dense canopy (Grigadale Arboretum 2023). Bill Funk (2015) includes it among the Mexican oaks that have grown well and formed outstanding trees at Mereweather Arboretum in Victoria, Australia. But it is at Hackfalls Arboretum in New Zealand that the finest specimens in cultivation are to be found. Bob Berry collected the species from both the Western Sierra Madre (Michoacán) and the Eastern Sierra Madre (Veracruz), i.e. from what Trelease originally treated as different forms but Muller determined were indistinguishable (see below). Berry found they appeared to differ in acorn size and leaf shape, with the eastern form showing longer petioles. The species is semi-deciduous there and has displayed interesting phenology in spring (September/October), when old leaves are red and still on the tree as new leaves emerge covered in rust-coloured tomentum, creating an effect which Berry compared to that of a scarlet oak. The tree of Veracruz origin has shown the best colouring. The largest specimen at Hackfalls had reached 26 m × 84 cm dbh in 2020. Some of the trees at Hackfalls may be hybrids with Q. planipocula and Q. xalapensis, and Berry also grew several hybrids from seeds collected from his own Q. calophylla specimens, putatively crossed with North American red oaks including Q. imbricaria, Q. shumardii, and Q. palustris (Cameron 2020; Berry 2016).

The bark is used in traditional Mexican medicine to soothe toothache, and its effect is said to last for two weeks. The wood is used for cabinet making, and in Chiapas and Veracruz the leaves are used to wrap tamales by laying one on another, in the form of a cross (Romero Rangel et al. 2015; Larousse Cocina 2023).

The scientific name of this species was subject to one of the more remarkable incidents in oak nomenclature. In 1801 Luis Née applied the name Q. candicans to a medium-sized oak he found near Tixtla, Guerrero in 1799, but the herbarium specimen he used was a leaf that, though lobed like a young leaf of the oak species and sporting white undersides, was in fact from a plant in the Asteraceae (daisy family). The name was taken up in 1924 by Trelease, who used it to distinguish an oak species found in the Eastern Sierra Madre, similar to what Schlechtendal and Chamisso in 1830 had called Q. calophylla, found in the Western Sierra Madre. Muller (1942) determined that the two species were indistinguishable, and so Q. candicans, as the earlier name, became the accepted name and Q. calophylla its synonym. Née’s specimen in the Madrid herbarium seemed to convince most botanists as bona fide, including Dennis Breedlove, who annotated the label as the proposed lectotype for Q. candicans; only Alphonse de Candolle smelled a rat, writing in 1864 that it looked strange for an oak and seemed closer to Populus alba. It was not until 2018 that Valencia et al. determined that the specimen was in fact Roldana lineata (Asteraceae), which meant Née’s name was transferred to that species and Q. calophylla was restored as the correct name for the oak (Cameron 2023).

The epithet derives from the Ancient Greek κᾰλός (kalós, ‘good, beautiful, noble’) + φύλλον (phúllon, ‘leaf’).