The world’s tiniest trees can grow just a few centimetres high – discover more about their adaptations to the freezing Arctic
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To see the top of a tree, it’s likely you’ll have to crane your neck upwards to see great, green canopies. In the Arctic, however, trees are so small that you can step right on top of them as you walk across frozen tundra.
Growing to just one to six centimetres in height, the dwarf willow (Salix herbacea) is the world’s tiniest tree. Although they don’t possess a traditional tree-like appearance, the dwarf willow is able to produce a single woody stem with branches, allowing it to be firmly part of the tree family.
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The reason behind these plants’ tiny height is, in fact, an ingenious adaptation to protect against the cold climate. In the summer, air temperatures can be eight to nine degrees Celsius warmer at ground level compared to just thirty centimetres above it. As such, dwarf willow grows low to take advantage of the warmer temperatures and calmer winds. As well as this, staying low helps growing buds avoid the erosion that strong winds bring.
A lack of summer warmth combined with the short growing season also means the plants run on limited energy. All resources must be spent on developing leaves, flowers, seeds and roots – meaning little energy is left over to produce wood to become tall like its larger counterparts.
Even at altitudes greater than 1,500 metres, you’ll find these hardy plants around. But how exactly do they survive?
Although the Arctic is a dry desert – with limited rainfall and liquid water only in the top few inches of soil – plants are still able to utilise this scant water to survive. Because of the cold, evaporation is very slow, with moisture at the surface very abundant.
Another important factor for plant growth is adequate sunlight. Typically, all areas of the earth receive about the same number of hours of daylight per year – around half the year. Yet in the Arctic, sunny weather comes just once during the summer. As such, the short growing season in the North means life cycles of both dwarf willow and other plants must be adapted to take advantage of conditions when they are at their prime.
Staying evergreen all year round is another adaptation dwarf willow possess – alongside other plants such as moss campion – in order to be able to grow and use sunlight ass soon as it becomes available.
What else grows in the Arctic?
Around 1,700 species of plants exist in the Arctic, despite the vast permafrost and freezing temperatures of the tundra. In fact, many of these species are able to thrive and grow under a layer of thick snow.
These plants include dwarf shrubs, herbs, mosses, lichens and graminoids (grass-like plants). Each possesses a unique set of adaptations helping it to survive. For example, the bearberry has leather-like leaves and hairs as protection from the cold. Meanwhile, the Arctic poppy has flower heads which follow the sun, along with cup-like petals to help absorb solar energy. Lichen – a vital food source for caribou – grows thickly on the ground and rocks, with its fuzzy covering providing additional protection from wind.
In contrast, just two species of plant live in Antarctica – Antarctic hair grass and Antarctic pearlwort, both of which are found in small clumps near the coast of the Antarctic Peninsula.
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