Italian alder

Alder trees: facts and stories

In the past, alder trees were associated with evil, probably because their bark goes black with age, their foliage is dark, and their buds and sap are red. When this tree is pruned or cut down, it ‘bleeds’ a lot with this sap, which gives the wood a startling orange-reddish colour.

This has led to alders being included in many superstitions and legends. The landscapes that they grow in are also quite unsettling: usually marshes or swamps. Dark alder groves therefore became known as homes for witches, ogres and other nightmarish creatures. Alder trees were said to grow at the border between this world and the afterlife, so they were associated with imminent death.

In Germanic cultures, alders inspired poems, stories and music during the Romanticism movement. The Erlkönig story (literally ‘alder king’) tells of an evil creature who drags children and travellers to their deaths.

Alder trees aren’t just known for creepy things though: in Ancient Rome, they were associated with eternal life. Pliny the Elder wrote that “the alder, when driven into the ground in marshy localities, is of everlasting duration, and able to support the very heaviest weights”. For Celtic cultures, the tree symbolised solidity and persistence. For anyone having to endure long ordeals or put up with periods of hardship, the tree was associated with perseverance.

Did you know?

Alder trees are some of the only trees that are adapted to growing in water. They’re often found growing in wetlands, as they find it easy to grow in waterlogged soils. Over the course of their evolution, alder trees developed special attributes through prolonged contact with water.

Their wood is very hard-wearing when in water, but is soft and degrades easily in the air. The wood has a high concentration of tannins, which dissolve in water and make the cell walls in the wood stronger. This prevents alder wood from rotting. When underwater, the wood actually becomes rock hard! Alder wood has long been used in helping to channel rivers and also in making locks or mills. Without alders, Venice wouldn’t exist! The millions of stilts that hold up the city are made from alder wood. The same goes for the docks in Amsterdam’s canals.

Another fascinating adaptation that alder trees have undergone through their evolution is in their fruit. The tiny seeds that escape from the mini woody catkins (which look like conifer cones) are each fitted with small corky wings (achenes). These wings act like two little floats, so they can be carried away by the currents in rivers and streams. This enables alder trees to disperse their seeds and reproduce over long distances.

The benefits of Italian alder trees

Alders are allies when it comes to soil health (see above). Their roots work to stabilise, decompact, aerate, enrich and decontaminate soil. And what’s more: they draw up a lot of water too, so they can help to dry out the soil and reduce flooding.

Alders are also allies when it comes to biodiversity. As the species is quite rare in Brussels, the city’s range of trees is enriched by its presence here. It can serve as shelter and a source of food for all kinds of insects. Flowering very early in spring, the tree feeds the first pollinators of the season. All through winter, the tree’s small seed catkins remain on the branches and act like mini feeders for small birds (passerine birds).

Lastly, alder trees have many natural medicinal and dyeing properties, but these have largely been forgotten.

Alder trees grow quickly and show good resistance to urban pollution. They aren’t fans of drafts or sudden changes in temperature though. Unfortunately, this soil ally is threatened by Phytophthora mould. Since the 1990s when it was first discovered, this mould has been linked to lethal root and collar rot in alder trees.

How to recognise an Italian alder

Fruit

ovoid woody catkins that look like conifer cones; visible on the tree throughout winter

Seeds

tiny, winged

Leaves

shiny dark green top sides, paler green undersides; heart-shaped (cordate); rounded teeth at leaf edge (crenate)

Foliage

green in spring through to autumn; still visible on the tree at the start of winter, but no foliage thereafter (deciduous)

Bark

brownish grey, turning blackish grey with age; cracked

Specifics about this tree

This tree is a focal point on the urban landscape. It helps to shape Place Marie-José: without it, the square would look completely different.

This tree is also counted as a remarkable tree because it is a rare species for Brussels. This particular specimen is one of the 20 largest Italian alders in the region. It isn’t easy for alders to reach this size though, as they are threatened by Phytophthora mould. Since the 1990s when it was first discovered, this mould has been linked to lethal root and collar rot in alder trees. This mould is mostly transmitted along waterways.

If this specimen has escaped the disease up until now, it is probably because it is isolated. It was also planted in a place that suits it quite well: at the bottom of the valley, where it is often wet and sometimes waterlogged. The tree has a role to play in reducing the effects of flooding.

It is also responsible for giving the Marie-José STIB stop all of its charm. People gather under its foliage and on the nearby benches when waiting for trams 8 and 25. It goes without saying that it’s more pleasant waiting under the tree’s dome of greenery than under a glass/metal bus shelter. Do you think everyone takes notice of its presence?

(Story and photos created by Priscille Cazin- Sylvolutions)

This portrait is:

- Enriched with an illustration from the Belgian Federal State Collection on permanent loan to the Meise Botanical Garden.

- An initiative of Christos Doulkeridis, Mayor of Ixelles , Audrey Lhoest, portfolio holder for Environment, Green Spaces and Planting, and Tourism and the Ixelles Communal executive