The environment in the Arctic Circle is very hostile.
The habit of forming mycorhizas is found more frequently in warm climates than cold; indeed, the percentage of the flora exhibiting this peculiarity seems to increase with a certain regularity from the Arctic Circle to the equator.
It is continuous round the pole and roughly is bounded by the arctic circle.
The tree is very widely distributed, growing abundantly on most of the mountain ranges of northern and central Europe; while in Asia it occurs at least as far east as the Lena, and in latitude extends from the Altaic ranges to beyond the Arctic circle.
Even within the Arctic Circle they are in many localities abundant and excessively bloodthirsty during the short summer.
