ALDER: CHARACTERISTICS, HABITAT, CULTIVATION, USES - BIOLOGY - 2024

The Alder (Alnus glutinosa) is an arboreal species belonging to the Betulaceae family. It is commonly known as alder, common alder, black alder, humerus, altza, and ameneiro. It is a beautiful and elegant tree that receives various uses and is characterized by its unique color (wood and leaves).

It is a tall tree (averaging 25 meters), with a pyramid-shaped crown (like a conifer) in its early years, and it becomes round in appearance over the years.

Alnus glutinosa has a pyramidal crown in its early years. Source: Bruce Marlin

Leaves and wood change color once they are cut or fall from the tree. The wood just cut from the tree has a yellowish color, but this color turns reddish over time. In particular, alder wood can resist and remain intact for many years while submerged in water.

It has medicinal properties such as lowering cholesterol, fighting tonsillitis and pharyngitis. It is often used as a pain reliever, to relieve nasal congestion, as well as to wash wounds.

The bark has a large amount of tannins and its infusion is used to control diarrhea. The branches next to the freshly cut or pruned foliage serve as a dewormer for birds, and as a tanning agent.

Alder has a useful wood for making kitchen utensils, tool handles, toys, boxes, and other light woodworking materials.

The alder is a species that has a symbiotic association with actinomycetes to form nodules on its roots and in this way obtain nitrogen and enrich or improve the soil.

characteristics

Appearance

-Species: Alnus glutinosa (L.) Gaertn.

Some synonyms for the common alder are: Alnus glutinosa subsp. antitaurica, Alnus glutinosa subsp. barbata, Alnus glutinosa subsp. betuloides, Alnus glutinosa subsp. glutinous.

The black alder acquires a rounded crown over the years. Source: Crusier

Habitat and distribution

The alder is a tree that can be associated with many other tree species that coexist in areas near watercourses or streams. This tree grows well in moist, deep and relatively acidic soils.

It is a demanding species in terms of water requirements, but it manages to survive semi-dry times, and thrive in hot or cold climates. In fact, this tree can withstand a temperature of -40 ° C. It develops up to 1700 meters above sea level, in mountains at the bottom of valleys.

It is a species native to Europe. Likewise, the literature indicates that its origin may be in Asia or Northwest Africa.

Alnus glutinosa is present in Albania, Algeria, Austria, Azores, Belgium, Chile, Denmark, Russia, Finland, France, Germany, Greece, Ireland, Italy, Hungary, Indiana, Iowa, Iran, Michigan, Minnesota, Morocco, Holland, New Zealand, Ohio, Ontario, Poland, Portugal, Romania, Sweden, Switzerland, Spain, Turkey, Ukraine or Siberia, among others.

Alnus glutinosa. Source: pixabay.com

Symbiosis

The nodules in Alnus glutinosa produced by Frankia sp. (an actinomycete prokaryote) can form between the second and third week of plant germination. This nodulation is stimulated if there are low concentrations of nitrates, and is inhibited when the external concentration of nitrogen is high.

From experimental inoculations it has been possible to determine which strains of Frankia sp. Are capable of forming efficient nodules for nitrogen fixation with Alnus glutinosa, and not only structural ones.

Additionally, the genus Alnus is associated with mycorrhizae, an important interaction that works for the absorption of nutrients, an increase in nitrogen and phosphorus, and an increase in plant health.

Specifically, in Alnus glutinosa, an effect of greater tree development has been found due to the simultaneous inoculation of Glomus intraradices (mycorrhizal fungus) with Frankia sp., Compared to when the microorganisms are inoculated separately.

That is, the microorganisms together can increase the nitrogen and phosphorus content in the leaves of this species growing in degraded alkaline soils.

From an ecological point of view, this is a great contribution made by the presence of Alnus glutinosa in soils. In short, it enriches the soil by providing it with more nitrogen and phosphorus that may be available for the development of other plant species.

Alnus glutinosa is a deciduous species resistant to very low temperatures. Source: wikimedia commons

Culture

Spread

It can be through seeds obtained from female catkins. These seeds dry in the sun even when they are supported by catkins.

Later they are sown in temperatures of 25 to 26 ° C during the fall or spring. It is important that the temperature is kept in this range in order to guarantee good germination.

Pruning

Pruning for this tree can be done as many times as required.

Irrigation

The water requirement of this tree is very important, since if it has to lack water, the individual can die. In the case of ornamental cultivation, irrigation must be abundant to guarantee water availability regardless of environmental conditions.

Floor

The common alder requires well aerated or loose soils and with a good amount of organic matter. The soil must retain permanent moisture due to the demanding water requirement of this species. The black alder does not support the presence of limestone where it is growing.

Light

This species must be directly exposed to the sun.

Alnus glutinosa forest. Source: Bernd Schade

Applications

The black alder wood has medicinal properties as it works to lower cholesterol, fight tonsillitis and pharyngitis. It is often used as a pain reliever, to relieve nasal congestion, and to wash wounds.

The bark has a large amount of tannins and its infusion is used to control diarrhea. The branches together with the freshly cut or pruned foliage serve as a bird dewormer, and as a tanning agent.

Likewise, wood is not considered of good quality, but because of the ease with which it is turned, it is used to manufacture pieces such as handles, pencils, cutlery, clogs, toys, boxes, among others. Wood is durable and is also used as fuel.

The property of this wood to change color allows it to be confused with other nobler woods such as mahogany. The leaves serve as a green dye, the bark to dye red, and the branches to dye brown.

On the other hand, the common alder serves as an ornamental species, to recover slopes, channels and eroded soils. Additionally, black alder is used as a windbreak barrier.

Alnus glutinosa is a species that has a symbiotic association with actinomycetes to form nodules on its roots and in this way obtain nitrogen and enrich or improve the soil.

Male and female inflorescences of Alnus glutinosa. Source: Stefan.lefnaer

Preparation modes

- Leaves: it is recommended to apply the fresh leaves directly on the injured or sore areas. Only the contact between the skin and the leaves produces an analgesic effect.

- Decoction: 15 grams are taken from the bark, added to half a liter of water and boiled for 10 minutes. Later it is filtered and can be stored to wash wounds, treat hemorrhoids or rheumatism.

- Gargling: to gargle it is necessary to boil 40 grams of the bark of the alder in one liter of water. It is subsequently filtered and allowed to cool. With this preparation, gargles are performed and the irritation of the throat and pharynx is deflated or relieved.

Toxicity

In no way should the leaves be consumed directly as their intake produces undesirable effects such as nausea, dizziness and vomiting. Although this last effect could be beneficial in case of poisoning from another cause.

References

1. Molina, M., Medina, M., Orozco, H. 2006. The effect of the Frankia-mycorrhiza-micronutrient interaction in the establishment of Alder trees (Alnus acuminata) in silvopastoral systems. Colombian Journal of Livestock Sciences. 19 (1): 39-48.
2. The tree. 2019. Alnus glutinosa. Taken from: elarbol.org
3. Arbolapp. 2019. Alnus glutinosa Alder. Taken from: arbolapp.es
4. Sánchez de Lorenzo-Cáceres, JM 2019. Alnus glutinosa (L.) Gaertn. Taken from: arbolesornamentales.es
5. Catalog of Life: 2019 Annual Checklist. Species details: Alnus glutinosa (L.) Gaertn.
6. Herbs and medicinal plants. 2019. Medicinal properties Alder. Taken from: herbsyplantasmedicinales.com
7. Infojardín. (2002-2017). Alder, Black Alder, Alno Alnus glutinosa (L.) Gaertn. Taken from: chips.infojardin.com