Hello! I don’t know about you, but I love alder trees. They look like ladies draped in beads! They are also a commonly found tree and one which you should recognise (you are sure to find many on your nature walks.) So, today, we will learn how to identify an alder tree. Are you ready? Let’s get started!
First, a few quick facts: the alder, or Alnus glutinosa, is a member of the Betulacea family. It can live for 60 years and can grow up to 28m tall! Then, it is monoecious, with both male and female flowers growing on the same tree.
What does an alder tree look like?
Alder trees have distinctive, triangular shape that makes them stand out from many of our other trees. It’s horizontal branches are longer at the bottom of the tree than they are at the top. They are also distinctive in having little wooden cones (which makes it look like a beaded lady!)
Its leaves are round, dark green, thick and shiny, with an indented tip and wavy edges. While it’s leaf buds are a soft purple or mousy grey colour.
It’s male flowers are catkins, which are distinctively green with red slices when immature, then loose and yellow once they have matured. While it’s female flowers are the cones. These start as green oval appendages, then turn woody after fertilisation. Once open, the alder’s seeds are released. The seeds are really tiny and carried on both wind and water.
Lastly, the bark of the alder is distinctively spotty! At least on the younger bark. These orangey coloured spots are called lenticels and are actually little breathing holes!
Where does alder grow?
Alder loves cool, moist earth and can be found growing near ponds, rivers, lakes, marshes and in wet woodland. A useful tree, the roots of alder stabilise the soil, reducing water and flood erosion in this areas.
It is also a pioneer species and one of the few trees which can flourish in boggy, nutrient-poor soil. In fact, it lives in a symbiotic relationship with a nitrogen-fixing bacteria called Frankia alni. Together, they help enrich and stabilise the soil ready for new species to grow.
Who loves the alder?
Alder trees are loved by both birds and bees, who enjoy feasting on its seeds, pollen and nectar. In particular, it is favoured by birds such as the goldfinch, siskin and redpoll. In addition to the bees and birds, it is also loved by several moth species, such as the alder kitten and hook-tip, whose caterpillars feast on its leaves.
How is the alder tree used?
Alder wood is pretty special, in that instead of rotting if submerged in water, it actually solidifies and turns rock solid. So much, that it has been used to support the houses and canals of Venice. It is also used in boat making and in canal lock gates.
What is an interesting alder fact?
The alder woods found growing near marshes and bogs and are called carrs.
Well… There we go! I hope you enjoyed reading all about the alders and have learned how to identify an alder tree? Remember, if you see a triangular tree adorned with beads and baubles, it is most certainly an alder. If you want to learn more about alders, you can also visit the Woodland Trust or, return to our field guides home page for more trees, plants and wildlife.