To make it through winter, trees have developed two very different strategies.

Deciduous trees, whose broad leaves are too delicate to survive the freeze, pull their sugars back into the body of the tree and let their leaves die and fall, as we explored in a previous EarthDate.

Coniferous trees—like pine, spruce, fir, and cedar—have a few different solutions.

First, their “leaves” are needles, adapted to the cold. They’re thick, have less surface area, and are coated with a waxy substance called cutin, which traps moisture within them.

So that the needles are not damaged by freezing, as cold weather approaches, water within their cells moves to spaces between the cells and concentrates with sugar to lower its freezing point.

The whole tree, in fact, produces a protein that acts like antifreeze, binding ice crystals and causing them to form less-damaging hexagonal shapes instead of their traditional needle form.

This system works so well that evergreen needles can stay on trees through several winters. They fall off only due to age and are quickly replaced by new needles.

By retaining their leaves, evergreen trees also retain their nutrients. Preserving their nitrogen, potassium, phosphorus, calcium, and magnesium allows them to survive in extreme environments, like high-mountain soils that may have little of these minerals.

And staying green throughout the late fall and early spring allows them to conduct photosynthesis and produce sugars when deciduous trees can’t.