Quercus × dysophylla Benth.

Quercus × dysophylla was described as a species by George Bentham in 1840 from specimens collected by Karl Theodore Hartweg in Huasca, Hidalgo, Mexico, while collecting for the Royal Horticultural Society, but it is now accepted to be a natural hybrid. While the parents are easily distinguished, the hybrids can present a range of intermediates. They can usually be identified by having broader leaves than Q. crassipes, often with a few teeth, and with the tomentum more yellowish on the leaf underside. They differ from Q. crassifolia in having narrower leaves with fewer or no teeth.

In some gardens in the UK, this hybrid has grown rapidly. At Sir Harold Hillier Gardens, there are two trees grown from Mexican seed collected in 1999, which were 12.3 m × 23 cm in 2017 and 8.8 m × 38 cm in 2012. At Chevithorne Barton, a grafted plant was 6 m × 13 cm in 2017 (The Tree Register 2025). In addition, it also grows at Royal Botanic Gardens, Kew, at Penrice Castle, Wales, and Thenford House, Northamptonshire. In Belgium, it can be found at Meise Botanic Garden (Plantcol 2021). At Arboretum des Pouyouleix, France, a tree planted in 2013 was 7.5 m × 21 cm in 2021 (B. Chassé pers. comm.). At Arboretum de la Bergerette, France, a plant grown from seed collected as Q. crassifolia appears to belong here. A tree seen at Iturraran Botanical Garden, Spain, had mostly entire leaves and was about 15 m tall in 2019.

The epithet ‘dysophylla’ is from ancient Greek meaning bad or abnormal leaf. It is formed from φύλλον (phúllon, ‘leaf’), and the prefix δυσ- (dus-, ‘hard, difficult, bad’), the opposite of εὖ (eû, ‘well, good’) as in ‘eulogy’; the prefix occurs in English words such as ‘dysfunctional’ and ‘dystopia’ – not to be confused with the Latin prefix dis, meaning opposite, as in ‘disrespect’. The epithet’s relevance to this plant is uncertain. Cameron (2019) suggested that it may relate to the variability of the leaves, but this would hardly be unusual for a Mexican oak. He also pointed out that Bentham seemed to have a penchant for this epithet: he used it for seven species with little in common, in various families, and is the only author to have used it as an epithet. It is worth noting that before publishing these names, Bentham had worked on the genus Dysophylla, describing several species in 1829–1830 from specimens collected by Wallich. When Blume described Dysophylla in 1826, he did not give a derivation for the name, but the type, Dysophylla auricularia, is said to be bad smelling (Stevens 2004). One of the first generic names to use the prefix ‘dys’ was Dysoda, which means ‘fetid, foul-smelling’, and refers to the unpleasant smell of the plants (Loureiro 1790), but it seems unlikely that this sense applied to the oak Bentham described as Q. dysophylla.