Weird and wonderful members of the plant kingdom - dealing with snow

Plants have evolved many strategies for dealing with inclement conditions. In the Canadian Lakes District, for example, trees have learned to grow so densely and closely together, that the snow stays on top of the spruce trees and the forest floor remains not only bare of snow, but warm. Many plants take advantage of this insulating layer to thrive under the spruces, as do hibernating animals. Evergreens, like spruce, are the most common form of adaptation to snow; they use a variety of techniques to protect themselves in climates that may be almost permanently frozen at ground level, including changing shape, leaf type, root system, and colour. Their name, evergreen, describes the most important adaptation. They are always green. Because they don't drop their leaves when temperatures cool, they don't have to re-grow them in the spring and this is crucial because growing new leaves takes a lot of energy. Plants get their energy from the soil and from the sun. Frozen soil doesn't contain many accessible nutrients and the sun usually remains low in the sky. These two factors limit the amount of energy available to the tree. By keeping their leaves, the evergreens are able to use that limited energy for structural growth rather than producing leaves. Because the ground freezes for months on end, roots are unable to get water. The adaptation id narrow needle-like structures limits water loss through transpiration. In addition, evergreen needles do not contain much sap, which means they don't risk of needle damage in freezing temperatures. The dark green needles absorb sunlight, and since they are always present, once temperature start to get warm, photosynthesis begins instantly. The conical shape of the evergreens allows the snow to slide off the branches rather than pile up which could cause broken branches from the weight of the snow.

Lichens are hardy organisms. They have been detected on otherwise bare rock in Antarctica, as close as 264 miles to the South Pole. This is the most southerly occurrence of land life, and is even further inland than even birds will travel - what the plants find to live on is anybody's guess!

The Skunk Cabbage, hardly a lovely name, has a feverish tendency. The plant can increase its temperature to as much as 13 degrees Celsius above its surroundings, and so it melts its way through even the thickest blanket of snow, to allow oxygen and sunlight to reach its leaves.

Snow photograph by pononwi, used under a creative commons attribution licence