Run your hand along a spruce branch and it prickles. Sniff your fingers and they smell of resin. Around the spruce, the birches are almost bare and the ground is yellow with leaves, yet the spruce is as green as it was in July. So why don't spruce trees lose their needles in autumn? Look at the ground beneath one. There are brown needles lying there. Where did they come from?
What happens to a spruce when autumn arrives?
A spruce is a conifer, a tree with needles instead of broad leaves. The needles are its leaves: they catch sunlight and make food, just like a birch leaf. The difference is shape. A birch leaf is broad and thin like paper. A spruce needle is narrow, tough and covered in wax that feels smooth between your fingers.
Birches drop their leaves because broad leaves cannot survive winter. The ground freezes, the tree can barely draw up water, and water keeps escaping through the leaves. A broad leaf would dry out and freeze apart. The narrow, waxy needle loses very little water and copes with frost and dry winter air.
A spruce loses needles all year. It just never loses them all at once.
A single needle can stay on the branch for many years. When it is old enough it falls, and new needles grow at the branch tips every spring. That is why there are always brown needles under a spruce. Pines are easier to catch in the act: they shed many of their oldest needles in autumn, so look for yellow needles deep inside a pine branch in October. More autumn investigations are gathered in our autumn outdoor laboratory guide, and the birch side of the story is in why leaves change colour.
Why does this matter for children?
The spruce and the birch are two answers to one question: how does a tree survive a northern winter? Neither is wrong. Seeing that helps a child grasp one of biology's big ideas, that living things are adapted to where they live. The Norwegian curriculum asks young pupils to explore how organisms are adapted to their surroundings, and two trees in one garden make a perfect outdoor textbook.
Try it at home: needle versus leaf
Suitable for: 4–12 years
You need a few spruce needles, a birch leaf that is not yet dry, a white plate, a teaspoon of water, a magnifying glass if you have one, and paper and a pencil.
- Feel the needle and the leaf. Which is thicker, and which is smoother?
- Drip a few drops of water on both and watch where they sit as beads.
- Put both on the plate in a warm room, but not on a hot radiator.
- Check them every morning for four days and bend them gently.
- Draw how they look each day.
- Talk it over: which dried first, and did it match your guess?
⚠️ An adult helps collect twigs that are already on the ground. Do not eat needles or leaves.
What happens if you add a pine needle next to the spruce needle and compare those too?
Questions to wonder about
- Why does a Christmas tree drop needles indoors when a spruce in the forest keeps them all winter?
- The larch sheds all its needles every autumn. What might it gain from that?
- If a spruce replaces its needles bit by bit, is it still the same tree it was ten years ago?
Every child is made of good atoms. Next time you pass a spruce in the snow, look at the brown needles beneath it: a tree changing its clothes so slowly that no one sees it happen.
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