
Which trees have catkins?
Hello. In this tutorial, we will be learning about which trees have catkins – and what exactly catkins are. Are you ready? let’s get started!
Which trees do catkins grow on?
We have quite a few species of catkin-bearing trees, some with catkins that are more noticeable than others. And some bearing catkins, which you might not know are actually catkins! Our main catkin-bearing trees, are: alder, aspen, birch, hazel, oak, poplar, sweet chestnut, walnut and willow.
Amongst these trees, the catkins you are most likely to spot on your nature walks, are: alder, birch, hazel and willow.

Young alder catkins
Young, female alder catkins take the form or short, round, green cones. Young male catkins are short, thin, green and stubby, with a lattice pattern across them.

Mature alder catkins
Mature female alder catkins develop into woody cones, which release their seeds. Mature male catkins lengthen and soften into soft, dangly, green and pink catkins.

Birch catkins
Young birch catkins are short, thin, light brown and stubby, growing in clusters of 2-3. Mature catkins become soft, long yellow and dangly.

Young hazel catkins
Young, male hazel catkins are short, stubby and moss green with a mustard-coloured scale trims rotating across their surface.

Mature hazel catkins
Mature hazel catkins elongate to become soft, thin, dangly and a soft, mustardy yellow. Of note, the female flowers are small buds with tufty, bright red hairs.

Willow catkins
Willow catkins start off green or yellow and develop puffy, white-coloured seeds. So, if you see something white, puffy or fuzzy, it is most likely a type of willow.
What are catkins?
Believe it or not, catkins are actually flowers! Yes. Catkins grow on shrubs and trees and are dangly clusters of lots of tiny flowers. They just don’t look like flowers at first glance because they are not colourful and pretty.
There are two reasons for this. First, the petals on catkins are either so tiny and drab that you don’t notice them, or they do not actually have petals at all. Second, they do not need to be bright and beautiful, because they do not need to attract birds, animals or insects. The pollen on catkin-bearing tree is usually wind-borne.
Did you know, that most catkin bearing trees are coloniser or pioneer species. They are the first trees to grow in a new area – often before the habitat can support a large variety of insects or other animals. So, they depend on the wind to help fertilise their flowers. And wind does not much care for fancy blooms or pretty petals!
Are catkins male or female?
This is a good question! As you know, flowers can be male or female. The male flowers carry the pollen, which is used to fertilise the female flowers, which then produces the seeds. Some plants have their male flowers and female flowers on separate plants – these are called dioecious. And some have both their male and female flowers on the same plant – these are called monoecious. This is the same for trees.
For example, alder, hazel and birch are monoecious, which means both their male and female flowers grow on the same tree. But their flowers do not look the same. In these trees, their male flowers form the pollen-bearing catkins. While their female flowers are rather inconspicuous may be difficult to spot (at least in birch and hazel).
However, willow is dioecious. It’s male and female flowers grow on separate trees. But, in the willows’ case, and usefully for us, they both look like our typical catkin – making them easy to spot.
Summary
Well… there we go! A brief introduction to which trees have catkins and how to identify them. I hope you enjoyed this tutorial? Let me know in the comments. Happy nature walking and see you soon!
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Next, why not check out these links and resources:
- Identifying common catkins
- Identifying trees by their buds
- Catkins quiz
P.S. Looking for field guides? Check these out.
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