The colossal fan

It is hard to find a tree with more beautiful branches in Brussels: This healthy specimen blithely extends its impressive array of branches over the green by Avenue Secrétin, as well as the border pavement, two tram tracks, and also a row of angled parking spaces. It has a stocky trunk that’s very short and powerful, carrying a huge dome that takes up almost all the space in the avenue.

An expanded beauty

Starting at just 3 meters from the ground, the tree starts branching out in all directions. When it is bare in winter, its breath-taking structure is clearly visible. During other seasons, it forms a huge ball of foliage that makes it an unmissable landmark in the urban landscape: dark green in spring and summer, then red in autumn. In its structure, it is reminiscent a large isolated oak tree flourishing in full light in the countryside. This tree’s isolated, central position in a very densely built-up neighbourhood makes it a real landmark on the landscape.

Everything about this oak tree is great. The leaves can each reach up to 15cm long, in a size and shape that are different from those of native oaks. The leaves are lobed, but with very pronounced indentations between the lobes.

This tree is so remarkable that it was included in the inventory of natural heritage in 2001, and on the safeguarding list in 2003. No doubt this colossus needed some protection against the pressures of urbanisation. The attention given to it is well deserved, as the tree is from a rare species for Brussels: quercus frainetto (its Latin name), or Hungarian oak. With an impressive trunk that’s more than 4 meters in circumference, this tree is the biggest of its species in the region, as well as in the whole of Belgium.

In the prime of its life

Faced with an oak of this size, the question of age is often mentioned. Given its size, this specimen looks like it may have survived over centuries. To measure its age accurately, you would have to “core” the tree. This involves taking core sample with an increment borer: extracting a thin piece of the tree’s trunk from the outer bark to the central pith. The rings can then be counted on the sample. This method could injure the tree though, exposing it to unnecessary risk of attack by fungi, parasitic insects or bacterial infections. A less invasive method is to use tomography (an imaging technique similar to ultrasound) to see the inside of the tree. However, tomographers aren’t often found roaming the streets in Brussels!

So, we’ll have to rely on looking around the tree thoroughly, and on cross-checking these observations with the region’s archives – these steps allow us to step back in time into the tree’s history. In addition, while looking up towards the canopy, we can learn more by locating (and hopefully not tripping up on) the piece of rock planted in the middle of the lawn of the square. This is a memorial stone that bears just two dates: 1830–1930. The oak tree was planted here at the same time as this stone, in 1930, to commemorate the centenary of Belgium’s independence. Oaks have a reputation for living a long time – more than 2000 years for common oak (quercus robur) and sessile oak (quercus petraea), 300 years for the Hungarian oak (quercus frainetto). They are often planted to mark moments in history. This makes it possible to measure their age with precision.

So, here, we have proof that this tree is almost a hundred years old. According to its striking 5.11m circumference, we can conclude that it has gained around 4.5–5cm in circumference per year. This is enormous, when you consider that an isolated oak tree (benefiting from light in all directions) only grows by about 3cm per year. This Hungarian oak continues to surprise the region’s dendrologists, as it has shown particularly vigorous growth.

Although the Hungarian oak may have a much shorter life span than native species of oak, this living monument still has many beautiful years to come. Growing between a large nursing house and the Jette cemetery, this tree has a fate far different from the oak trees in our forests: it won’t be turned into planks anytime soon.

(Textes et photos par Priscille Cazin https://www.sylvolutions.eu)

Twinning

This colossal Hungarian oak tree, which inhabits the entire area of Secrétin Square in Jette, has been noticed by the Belgian Society of Dendrology. It has been twinned with an individual of the same species from the Wespelaar Arboretum : Botanicum Tree