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The Oak at La Porteña al Sur

I recently had the opportunity of seeing one of the largest pedunculate oaks (Quercus robur) in South America. It stands at the edge of the large lawn in front of the homestead at La Porteña al Sur, once part of a vast estancia (estate) with a rich history stretching back to arrival of the Spaniards in the region of what is now Buenos Aires. The tree is remarkable for the size it has attained in a relatively short time, but also for its habit. And like the cork oak across the River Plate in Parque Anchorena, Uruguay, it raises questions about the longevity of oaks in this area.

La Porteña al Sur was once part of a large tract of land that was given out to early Spanish colonizers in the late 16th century. These estates, known as suertes, were four and a half square leagues (about 10,500 hectares) and

The green bower inside the La Porteña al Sur oak

extended along the coast of the River Plate. After changing hands several times, the property was acquired by Simón Pereyra in 1850. Simón died two years later, at which time his son, Leonardo Pereyra Iraola embarked on a five-year tour of Europe, where he was able to appreciate the beauty of the many wooded parks and estates he visited, and to learn of the advantages of forestation: namely, soil conservation, mitigation of erosion, and the creation of a microclimate that benefits livestock. Inspired by what he saw, on his return he began extensive plantations of trees on his estate, for which purpose he contracted a Belgian landscape designer, Carlos Vereecke. This project was such a success that in 1948 it was to catch the attention of the populist government of President Juan Perón, who expropriated it, ostensibly to save this dendrological and cultural treasure from being lost through the continuous subdivision of inherited property (Argentine law follows the Napoloeonic code in that respect). The expropriation did not include the section where the Quercus robur had been planted, but it is believed that the tree was planted as part of Leonardo’s forestation project.

The tree is estimated to be about 130 years old, and has a height of 16.5 m and the trunk’s girth measures 4.19 m at 1.20 m (smallest trunk circumference below the lowest fork), neither dimensions being particularly

Ground layering on a low-lying branch

noteworthy. The crown spread, however, extends to an average 34.3 m. The long branches extend down to the ground, so that the there is no space between the canopy and the soil: one does not so much go under the tree as into it. And inside the canopy is where this oak is most impressive, where the long spreading branches create a cool and restful “green bower” of dappled light and lush greenery.

Peter Laharrague has written about notable oaks in Argentina in his article “The Cultivation of Oaks in Argentina” in International Oaks No. 12, 2000, and listed two specimens of Q. robur with slightly larger dimensions, and slightly lesser age. When I wrote to him asking for details, he informed that he had in fact measured the oak at La Porteña al Sur in 2002, and recorded a height of 19 m. (It may be that the tree lost apical branches since then, or perhaps that I underestimated the height: the tree sits in a small dip, and Peter may have done a better job in compensating for that.) For girth he measured 3.90 m and 28 m for crown spread, indicating a healthy growth rate in the last 12 years.

In one aspect, this oak reminded me of Charlie Buttigieg’s article in the latest issue of International Oaks, where he writes of multiple ground-layered branches in Quercus canariensis in Australia. Here a particularly long branch descends to the ground and it appeared that it had rooted, because it did not budge when I attempted to lift it. Several shoots have sprouted straight up from the branch.

The oak appears, at a distance, to be in good health, but on closer inspection the proliferation of epicormic shoots raises concerns. They may be a temporary reaction to fungus attacks, or perhaps a 

Epicormic shoots: sign of trouble?

more worrying indication that a fast growth rate implies a shorter life span. According to Peter, a few years ago the tree was in a similar state of decline, and after some soil fertilization and other measures it had recovered. Perhaps it requires another lift-me-up. But it is at any rate a remarkable tree and the space under the canopy is quite special: a genuine green bower that could serve as the ideal place for a family picnic—or even a banquet for several dozen.

More photos of the Q. robur at La Porteña al Sur can be viewed in a photo gallery here.

With thanks to Andrea Pereyra Iraola, the current owner, for the invitation to view this remarkable tree.