In certain areas it is possible to find a few broad-leaved trees in scattered patches, but trees in the boreal forest are almost exclusively needle-leaved evergreens. The needles are thin and arranged in patches, helping to shed snow and block wind. They have a waxy coating which helps prevent water loss, and contain a thick, sugary sap that prevents freezing in the winter.

These needles influence the numbers and types of animals that live in the boreal forests. They can not support the large numbers of vegetarian species which, in more southern regions, munch away at the softer, more digestible leaves of broad-leaved trees. Needles are nearly inedible to everything from caribou to small rodents to most birds.