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Pages from Gert's book
It was a great pleasure for me to be able to write about my...
Gert Fortgens | Feb 15, 2024
Quercus marlipoensis acorns
A new study has analyzed the germination characteristics of...
Website Editor | Feb 15, 2024
Gall on Quercus grahamii
A new species of oak gall wasp has been named in honor of...
Website Editor | Feb 14, 2024

Plant Focus

A small but mature Alabama sandstone oak producing acorns © Patrick Thompson
A Critically Endangered dwarf oak 

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