Alder
Alnus, family Betulaceae
Deciduous trees and shrubs with cone-like catkins, found near water in cooler regions
Alders are trees and shrubs in the birch family, found mostly in cooler parts of the world. They have serrated leaves and produce both male and female catkins, often before the leaves emerge. Alders play a key role in enriching soil and are used for wood, dye, and traditional remedies.
- Alders enrich soil by fixing nitrogen with bacteria in their roots
- Their wood was used for the foundations of Venice
- Alder bark and wood provide dyes and tanning material
- Red alder is the largest and most common alder in the Pacific Northwest
- Alder catkins are edible but mainly used in survival situations
What does Alder look like?
Alders are mostly medium to large deciduous trees, though some species are shrubs. Their leaves are simple, arranged alternately, and have toothed edges. The trees produce two types of catkins: long, drooping male catkins and shorter, woody female catkins, which open to release seeds. The female catkins look like small cones and stay on the tree after seeds are released. Most alders lose their leaves in autumn.
Where does Alder come from?
Alders belong to the genus Alnus in the birch family. They are native to cooler parts of the world, especially in the northern hemisphere and the Andes. The name 'alder' comes from Old English and Latin roots. Fossil pollen shows that alders have been around for at least 58 million years. Over time, they spread to riversides and wetlands, where they became common.
When and how Alder blooms
Alders flower early in the year, often before their leaves appear. Male and female catkins grow on the same plant. The trees thrive in moist soils, especially near streams and wetlands. Their seeds are light and easily carried by wind, helping them quickly colonize open ground after disturbances like floods or fires.
How Alder is used
People have used alder wood for centuries, especially for underwater structures like piers, as it resists decay when wet. The bark and wood are sources of tannin for leather tanning and dyes for textiles. Some Indigenous groups use alder bark in traditional remedies, and the wood is valued in furniture and musical instrument making. The catkins are edible but not tasty.
Kinds of Alder
There are about 35 species of alder, ranging from large trees like red alder and black alder to small shrubs such as green alder. Some species, like white alder, prefer warmer, drier areas along rivers. Alders are divided into three main groups based on their bud and catkin features. Hybrids and species with uncertain status are also known.
What Alder means
Alders are important in ecology for their ability to fix nitrogen, improving soil for other plants. They are often among the first trees to grow in disturbed areas. Alder appears in town symbols, such as the coat of arms of Grossarl in Austria, and is referenced in art, like the film 'The Tree of Wooden Clogs.'
Traditions that use it
Questions people ask about Alder
Where do alders come from?
Alders are native to cooler parts of the northern hemisphere and the Andes, growing along rivers, streams, and wetlands.
What are alders used for?
Alder wood is used for underwater construction, furniture, and musical instruments. The bark and wood are sources of dye and tannin, and some cultures use the bark in traditional medicine.
How do alders help the environment?
Alders form a partnership with nitrogen-fixing bacteria in their roots, which adds nitrogen to the soil and helps other plants grow.
What do alder trees look like?
Alders are usually medium to large trees with serrated leaves and produce both long male and short, cone-like female catkins.
Are there different types of alders?
Yes, there are about 35 species, ranging from large trees like red and black alder to smaller shrubs such as green alder.
Good reading and sources
- Encyclopaedia BritannicaArticle
- USDA Plants DatabaseUS Department of Agriculture, Article
- Plants of the World OnlineRoyal Botanic Gardens, Kew, Plant database
- Where it has been recordedGBIF, Plant database
- Sightings and photos by naturalistsiNaturalist, Plant database
The facts on this page come from the Wikipedia article "Alder", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). Phool rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes. It is not medical or foraging advice: many flowers are poisonous, and traditional uses are reported, not recommended. If something is wrong, tell us. Last refreshed 2026-10-03.
