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Editor's Picks

Past IOS President Allen Coombes, Curator of Scientific Collections at Puebla University Botanic Garden, discusses leaf variability in Quercus ceirpes (still image from the documentary)
A new documentary by Maricela Rodríguez Acosta
Website Editor | Feb 17, 2026
Quercus miyagii acorn and dried leaves
A rare oak endemic to the Ryukyu Islands of Japan
Elion Jam | Feb 16, 2026
A moss-covered oak (Quercus orocantabrica) in Mata de Albergaria, Peneda-Gerês National Park, Portugal  © Amit Zoran
Steve Potter reviews a new book that features oaks
Steve Potter | Feb 11, 2026

Plant Focus

Quercus canariensis in Cornwall Park, Epsom, Auckland, New Zealand, the champion specimen in New Zealand, planted in the 1920s, 27.2 m tall with a trunk diameter of 209 cm (G. Collett pers. comm. 2026)  © Gerald Collett
Antonio Lambe shares his views on this threatened oak native to Iberia and North Africa

Hybrid Highlight: Quercus ×heterophylla F. Michx.

Named in honor of one of America’s first botanists, John Bartram, Quercus ×heterophylla is known by many as Bartram’s oak. This interesting hybrid can be found in the US where the parent species of Q. rubra and Q. phellos overlap (essentially most of the midwestern to southeastern states) and in collections. This hybrid can also be found in Europe in arboreta and private collections. One of the largest European specimens stands in the Garden Kingdom of Dessau-Wörlitz, Germany. It measures over 15 ft in circumference and is 65 ft tall.  A noteworthy specimen in the US is located in Philadelphia, Pennsylvania and has nearly identical dimensions of the grand European tree (16 ft circumference, 61 ft tall). This tree is believed to be a direct descendant of a Q. ×heterophylla grown by John Bartram on his property.

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Quercus ×heterophylla in the Garden Kingdom of Dessau-Wörlitz, Germany © Andreas Gomolka
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Detail of the leaves on the tree in Dessau-Wörlitz  © Andreas Gomolka

This is an attractive hybrid typically characterized by long, slender leaves with 6-8 shallow lobes. Acorns are typically small (3/8 to 1/2 inch diameter) with shallow, flattened cups. The acorns are usually light to medium brown with dark striations. Seedling trees will vary of course, some having larger leaves or lager acorns. This hybrid makes a pleasing street tree and there exists a great opportunity to make superior selections. 

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A young Quercus ×heterophylla in central Missouri, USA © Ryan Russell
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Detail of leaves © Ryan Russell