23 December 2021
Norway spruce, Picea abies. Illustration: Flora von Deutschland, Österreich und der Schweiz by O.W. Thomé from 1885.
The traditional Christmas tree in Sweden is the Norway spruce (Picea abies), a conifer with needle-like leaves. The needles have a slim outfit, a thick wax coating and several other physiological adaptations to survive the cold winter, but the tree can't cope with a temperature change of 30C degrees! Normally a needle lasts on the tree for a few years before it is replaced by a new one. But when we bring it indoors, the sudden temperature change is a huge shock to the tree, and after a few days several thousands of needles are lying on the floor...