Plant of the Month

Plant of the Month: December 2024

Durmast Oak

Quercus petræa (Matt.) Liebl.

= Quercus sessiliflora Salisb.

FAGACEÆ; Beech Family

The Durmast oak is common in its native home of Europe and W Asia, reaching N Iran, but I have encountered only one big old specimen in western North America. It may be undeservedly rare. This article shares all I know of the species.

Usually Durmast oak is decribed in tree guides in comparison to its cousin the far more common English oak (Quercus robur L.), also of Europe. The latter is better known both wild and cultivated, more variable, and more valued. Whether it is better-looking is subjective. It was these two oak species, largely, that caused John Claudius Loudon to write the following in 1854:

"The oak, both in Europe and America, is the most majestic of forest trees. It has been represented . . . as holding the same rank among the plants of the temperate hemispheres that the lion does among the quadrupeds, and the eagle among birds; that is to say, it is the emblem of grandeur, strength, and duration; of force that resists, as the lion is of force that acts. In short, its bulk, its longevity, and the extraordinary strength and durability of its timber, attest its superiority over all other trees, for buildings that are intended to be of great duration, and for the construction of ships. In one word, it is the king of forest trees."

Considering the rarity of Durmast oak in the North American nursery trade over the centuries, it is no surprise that so few are encountered here. The Seattle specimen at Garfield Playfield is obviously very old. The playfield dates from 1911 (then called Walla Walla playfield), and likely the oak dates from that period; it stands on the east border nearer the north end. It has been pruned to limit its width due to a ballfield. In 2011, it was designated an official City of Seattle Heritage Tree.

A Seattle Park Department inventory of trees in its nursery in 1893, lists English Oak and 4 other species, but no Durmast oaks.

English oak has given rise to dozens of cultivars including yellow-leaved, narrow-growing, and so on. The 2019 Hillier Manual of Trees & Shrubs book lists 18 cultivars, my 1996 book North American Landscape Trees lists 14. In contrast the Hillier book has only 4 Durmast variants, and my book 3.

Durmast oak is Ireland's national tree, also of Wales. Durmast is an English word used since the 1700s. Another name is Sessile oak, because its acorns are essentially unstalked --markedly unlike those of English Oak (on stalks 1 to 5 inches long).

From the 1791 book Flora Rustica by Thomas Martyn (illustrations below): "Durmast Oak differs very widely from the true British species [Quercus robur] . . . The whole tree has much the air of the Chestnut [tree], and is of a freer growth than the true Oak [Quercus robur]; and the bark is of a lighter color and smoother."

Seattle's big old tree measured in 2004 81.5 feet tall, its trunk 10 feet 10 and a half inches around. Now it is 86 feet tall, its trunk 12 feet and a quarter-inch around, and its north-south branch spread 88 feet. A specimen in Baltimore, Maryland, was cited in 2005 as 90 feet tall, its trunk 10 feet around; it may be deceased now.

Some Durmast oak cultivars are handsome enough to be well worth growing as ornamental trees. Possibly this species will be less weedy in Seattle than English oak has been. I have never looked in the neighborhood around the big Seattle tree, looking for seedlings. The two species do hybridize. It would seem that when the big Seattle tree blooms, some pollen from other oaks may "father" some of its acorns.

Renowned British tree expert Alan Mitchell preferred Durmast oak to English Oak, and wrote in his 1981 book The Garderner's Book of Trees: "This is a far finer tree than the Common oak in growth, form and foliage. The bole is straight and clean without burs and the branches radiate mainly straight to make a high dome."

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