Quercus × filialis Little

Sponsor

Kindly sponsored by
The Trees and Shrubs Online Oak Consortium

The International Dendrology Society, The Wynkcoombe Arboretum, and several private individuals

Credits

Allen Coombes & Roderick Cameron (2026)

Recommended citation
Coombes, A. & Cameron, R. (2026), 'Quercus × filialis' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/quercus/quercus-x-filialis/). Accessed 2026-07-11.

Family

Fagaceae

Genus

Quercus
Subgen. Quercus, Sect. Lobatae
Q. phellos × Q. velutina

Synonyms

Quercus × inaequalis E.J.Palmer & Steyerm. non Watelet
Quercus × dubia Ashe non Newb.

Other taxa in genus

Glossary

dbh: Diameter (of trunk) at breast height. Breast height is defined as 4.5 feet (1.37 m) above the ground.
hybrid: Plant originating from the cross-fertilisation of genetically distinct individuals (e.g. two species or two subspecies).

References

Credits

Allen Coombes & Roderick Cameron (2026)

Recommended citation
Coombes, A. & Cameron, R. (2026), 'Quercus × filialis' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/quercus/quercus-x-filialis/). Accessed 2026-07-11.

The leaves of Quercus × filialis can lack lobes and teeth. Chevithorne Barton, Devon, UK, July 2016. Image © James MacEwen.

This hybrid was described from Poplar Bluff, Missouri from a specimen collected by E.J. Palmer in 1919 and was said to be intermediate between its parents in foliage, winter buds and fruit. The leaves were said to be very variable and often asymmetrical. Judging from herbarium specimens they can be nearly entire, to sinuately lobed or with up to three bristle-tipped lobes on each side, some reaching about ½ way to the midrib. (Palmer & Steyermark 1935; Little 1943).

Distribution United States Arkansas, Delaware, Illinois, Louisiana, Mississippi, Missouri, New Jersey, New York

Habitat Low hills bordering lowlands.

USDA Hardiness Zone 5-9

RHS Hardiness Rating H6

Taxonomic note This hybrid was first described as Q. × inaequalis, a reference to the often asymmetrical leaves. This name had previously been used for a fossil species, and Little proposed the new name, Q. × filialis, referring to the hybrid origin as the filial generation or offspring of a cross between parents of different species (Little 1943). Ashe applied the name Q. dubia in 1894 to what he presumed was a hybrid between Q. phellos and Q. velutina or Q. coccinea. It is now considered a syonym of Q. × filialis but is in any case an illegitimate name, as this epithet had also been validly applied to a fossil by Newbery in 1886 (Little 1943).

A massive specimen of this hybrid grows next to the Staten Island Museum, New York. It was planted in the 1930s by William T. Davis, the founder of the museum and an accomplished hybrid-oak hunter. The leaves display an intriguing range of wavy to shallowly and asymmetrically lobed margins, with the leaf base also asymmetric and sometimes almost auricular (see photos below) (Cameron 2022). A tree accessioned in 1925, from seed collected in Hot Springs, Arkansas, by E.J. Palmer, is at the Arnold Arboretum, listed in their database with a dbh of 47.3 cm in 2020 (Arnold Arboretum 2025). In Europe, Quercus × filialis grows at Chevithorne Barton, Devon, UK, and at Arboretum du Passadou, France.

Bronze young leaves of Quercus × filialis mature to glossy dark green, some with an occasional tooth. Chevithorne Barton, July 2016. Image ©James MacEwen.

The massive Quercus × filialis at Staten Island Museum, planted in the 1930s by William T. Davis. 14 August 2021. Image Roderick Cameron.

Quercus × filialis bark, Staten Island Museum, 14 August 2021. Image Roderick Cameron.

The buds of the Quercus × filialis at Staten Island Museum are closer to the Q. phellos parent, 14 August 2021. Image Roderick Cameron.

Quercus × filialis leaves showing variablity of lobing and leaf vase, Staten Island Museum, 14 August 2021. Image Roderick Cameron.

Quercus × filialis leaf undersides, Staten Island Museum, 14 August 2021. Image Roderick Cameron.

Quercus × filialis at the Arnold Arboretum, Massachussetts, USA; 11 September 2021. Image Roderick Cameron.

Quercus × filialis bark, Arnold Arboretum, 11 September 2021. Image Roderick Cameron.

Quercus × filialis at the Arnold Arboretum with buds that show the Q. velutina influence; 11 September 2021. Image Roderick Cameron.

Quercus × filialis at the Arnold Arboretum has leaves closer to the Q. velutina parenr; 11 September 2021. Image Roderick Cameron.

Quercus × filialis foliage at Arboretum du Passadou, France, in 2010. Image © Jan De Langhe, Ghent University Botanical Garden, 2010.

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