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Editor's Picks

The oak tree in Skjomendalen © Gerhard Sørensen-Fuglem and Cecilia Piccirilli Bjerkeset
An oak grows north of the Arctic Circle in Norway
Website Editor | Aug 14, 2023
Unusual symptoms linked to phytoplasma infection in Quercus humboldtiii, Colombia © Eric Boa
Symptoms linked to phytoplasma infection found in Quercus...
Website Editor | Aug 06, 2023
Different names are being used for one species.
Website Editor | Jun 20, 2023

Plant Focus

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

Is Quercus rugosa Showing Its Roots?

We know that some oaks, particularly Quercus robur, can produce forms with unusually cut leaves. Many of these have been documented in International Oaks and are listed at oaknames.org. We were very surprised, however, to find a very unusual shoot on a tree of Q. rugosa at the Puebla University Botanic Garden in Mexico.

Lobed Quercus rugosa
A lobed leaf on Quercus rugosa at the Botanic Garden of the Benemérita Universidad Autónoma de Puebla

This species normally has unlobed but distinctly toothed leaves, but a single shoot was recently found with leaves deeply lobed. It seems to be unstable as later growth produced normal leaves, but we will certainly be keeping an eye on it. What is happening here is not clear. It could be a simple mutation, but as we know that the Mexican oaks, which most often have unlobed or shallowly lobed leaves, derive from ancestors further north where deep lobing is more common, is this tree expressing an ancient and long-hidden gene? What it does seem to show is that the genetic difference between lobed and unlobed leaves in oaks, often an important identification feature, may be very small. The tree is about 25 years old and was grown from seed collected on Cerro El Pinal in Puebla.

Quercus rugosa tree
Later growth on the same shoot produced normal leaves

Allen J. Coombes and Maricela Rodriguez

Photos © Allen J. Coombes