Evergreen trees are pyramidal. Why?
Those who admire the shape of a Christmas tree might enjoy knowing that its shape has evolved in response to wind, snow, and light.
Evergreen trees – such as spruces, pines and firs – are collectively known as conifers. The world’s smallest and tallest trees are members of this family, and there are more than 550 species of conifers in all. Instead of having broad, flat leaves, conifers usually have needle-shaped or scale-like leaves. The shape of their leaves is an advantage, because they often grow in climates that sometimes feature abrasive, blowing ice crystals.
But why are they shaped like pyramids? Although conifers grow across the globe (except in Antarctica), they’re often found in places that have severe winters. So an evergreen tree’s shape helps keep wet, heavy snow off its upper branches.
Also, conifers tend to have shallow roots. In other words, they lack long, sturdy tap roots. So wind can sometimes knock them down. Their pyramidal shape reduces wind resistance and helps keep the trees standing upright.
And, finally, a conifer’s shape helps it get more light, in places where daytime can be short. That’s because the top branches of a pyramid-shaped tree don’t shade the bottom branches. Conifers have layered branches, with an open area between the layers. This helps wind pass through, and it helps the tree get enough light, especially when sunlight comes in at a low angle, as it does during the winter months.
Bottom line: The pyramid shape of an evergreen tree helps the tree thrive in windy, snowy conditions. It also helps the tree’s lower branches receive more light.