Alnus glutinosa Luszyn - Common Alder

Alnus glutinosa 'Luszyn', also known as Common Alder or Black Alder, is a cultivar found in a public park in the Polish city of Luszyn in 2016, initially mistaken for the columnar variety 'Pyramidalis'. 'Luszyn' develops a much wider canopy. Its branches are upward-oriented, with a broad conical crown. The leaves are dark green, ovate, and recurved. Its brown branches are adorned, from March onwards and before the foliage appears, with numerous, very decorative, pendulous yellow-green to brown catkins. This medium-sized tree thrives in waterlogged and poor soils, where it is sometimes the only one able to grow.

In harsh climates and poor, marshy, and suffocating soils, the Common Alder with its rot-resistant and lightweight wood reigns supreme. This deciduous tree from the birch family is widespread in the native flora of Europe, extending up to Scandinavia. It is sometimes called "vergne" or "verne". The variety 'Luszyn' is mainly distinguished by its serrated leaves. It is a small, pyramidal and airy tree, with drooping branches, reaching a height of 10 to 12 metres at maturity with an approximate spread of 5 metres. Its growth is rather slow. Its foliage is light green and vibrant, even lighter underneath and slightly sticky to the touch, especially on young leaves. The buds are purple and also sticky, particularly in winter. The spring inflorescence is a 2cm long kind of small cone called a strobilus, containing tiny winged fruits that will be dispersed by the wind. This tree retains its foliage for a long time.

As a pioneering species, loving water regardless of its source, the Common Alder can be used as a specimen tree, in groups, or to retain banks along streams, natural basins, or in waterlogged, acidic soils in damp undergrowth. It should be kept away from foundations and buildings, as its extremely developed root system (up to 4 metres deep) is capable of blocking drinking water pipes. The 'Luszyn' Common Alder has a distinctive appearance that makes it very attractive when planted alone. Otherwise, plant it with shrubs or trees that have similar requirements, such as Nyssa sylvatica or Bald Cypress. Plant ferns like Onoclea sensibilis at its base, in neutral to acidic and moist soil, in full sun or partial shade. An elegant small tree, ideal for stream or marsh scenes, in dappled shade or full sun.

The Common Alder is also used in forests to prepare and improve the soil before planting poplars. Considered a green manure by foresters, it cleanses and enriches the soil in which it is planted, as its roots convert atmospheric nitrogen into plant proteins. Its wood is almost rot-resistant in water and was once used for underground water conduits and gutters. A significant part of the city of Venice is said to have been built on Common Alder pilings.