It grows in the tundra, on the slopes of our mountains. We bend down to see it, its trunk, its branches, rise to about twenty centimeters. It belongs to the Willow family, the smallest tree in the world.
Too small to be seen
The covering willows do not stand proudly in the countryside. Under the botanist’s index, the mountain hiker can hardly believe he is walking through a willow forest… in the middle of an alpine slope. Likewise for the traveler of the arctic and subarctic regions, who cannot imagine in the tundras rub shoulders with the last trees still present at such latitudes, in a cold, extreme climate.
Flooring willows, some species in the world, measure at most about thirty centimeters. Their trunk is tiny, twisted, their branches hug the ground, their leaves remain tiny, short. Their flowers, male and female chestnuts, their silky seeds, are a good reminder of their family, the Salicaceae.
Far from Weeping willows, of white willows Along our rivers, Osiers of basket makers, a few Willows have adapted to life in extreme conditions, reducing their size to withstand the cold, strong winds, extreme conditions.
The smallest of them is found all around the Arctic Ocean, it is the last species woody from high latitudes. The Arctic Willow, Salix arctica measures 1 to 15 cm, barely. Its longevity, observed in Greenland, can reach 200 years …
The mountains of Europe welcome the stubby willow Salix retusa, the reticulated willow, Salix reticulata, the wild thyme willow, Salix serpyllifolia. All three are twisting, crawling sub-shrubs with trunk and branches more or less buried in the ground. The herbaceous willow of the snow combes, Salix herbacea, is denoted by its slightly smaller size, its erect branches evoking tiny forests.
They came from the depths of ice ages
Shortly after the dinosaurs disappeared, at the beginning of the Tertiary, Willows are present in ecosystems. They are going to be subjected to the most diverse climatic hazards for about fifty million years. They will see mountains grow, they will attack their summits, becoming crawling and tortuous, the leaves shortening, covering themselves with various protections, to resist the bites of the wind, cold, UV rays, and drought. The glacial times will push them back towards the plains, then will see them set out again in altitude following the retreat of the glaciers. Isolated from each other they evolve in multiple species, retaining their small size, their multiple adaptations to altitude and high latitudes.
Tree or sub-shrub?
If they are so small these Willows adapted to harsh climates, can we call them tree ?
According to the definitions, a tree is a tall, long-lived plant, the trunk of which stands upright, its ramifications developing into a crown at least 5 m high. This crown spreads out in the sun, offering its leaves the best exposition possible. The tree is anchored in the ground by its roots, and to support its structure is able to make real wood.
The willow trees meet all these criteria, except height. If we imagine them over the course of evolution reducing their size, bending, blending into the ground, adapting their leaves, growing slowly, very slowly, but for many years, then can we not continue to call them trees?
The men of the arctic and alpine zones have found many interests in Tiny Willows: fuel, source of vitamin C, medicinal role equivalent to tall Willows. Herbivores graze it, insects and spiders find refuge there. Alpine plants hug each other, protect each other.
The world’s smallest trees have adapted for millions of years to extreme environments. How will they react to climate change? Will they be able to adapt, are they in danger of disappearing, in competition with prolific species favored by milder temperatures?
Source: Au Jardin, conseils en jardinage by www.aujardin.info.
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