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Nature Notebook – Moss Photosynthesis in Winter

Surrounded by the blah-looking browns of decomposing vegetation, the greens of the mosses beckoned us to a closer look. We wondered if, like invasive plants, the mosses are capable of photosynthesis during winter.

Although they differ structurally from “regular” plant leaves, moss leaves also utilize chlorophyll to produce starch for the plant. They need water, some sunlight and temperatures that are at least just above freezing.

Roots do not absorb the necessary water. Mosses don’t have true roots, they have rhizoids. Their only purpose is to anchor the moss to its substrate. The leaves absorb water from the surrounding environment (dew, raindrops, snow, etc.) The light that penetrates a shallow snow cover is enough for photosynthesis. If the snow cover is significant, the moss just waits until the light level becomes strong enough.