Earth & Sky

Why do most evergreen trees have a pyramid shape?

Why do most evergreen trees have a pyramid shape? Does this shape help support the winter snow?

Many of these trees grow in places that have severe winters, and the tree’s shape does help keep wet, heavy snow off its upper branches. Conifers also tend to have shallow roots – they lack long, sturdy tap roots – so they’re subject to being knocked down by wind. Their shape reduces wind resistance – and helps keep the tree standing upright. The tree’s shape also lets it get more light, because the top branches don’t shade the bottom ones.

What’s more, the major branches of conifers are layered, 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. It’s also noteworthy that the trees have needles instead of broad, flat leaves – in climates that sometimes feature abrasive, blowing ice crystals. So those who admire the shape of a Christmas tree might want to recall that its shape has evolved in response to wind, snow, and light.

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