Have you ever heard that moss only grows on the north side of trees? It’s an old myth that probably started as a way to help people navigate in a forest. It’s not exactly true, though. If you use that advice to help find your way through the woods, you may end up getting lost.
In reality, moss can grow just about anywhere. Although it is most likely to grow on the north side of trees, rocks and other surfaces, it doesn't grow there exclusively.
Where moss is most likely to grow depends on where in the world you live. In the northern hemisphere, moss most often grows on the north side of trees. But in the southern hemisphere, moss most typically grows on the south side of trees and other surfaces. That's because the north side is the shadiest side in the northern hemisphere, and the south side is the shadiest side south of the equator.
Moss grows best in shady spots that are moist or humid. In a forest or woodland, where sunlight peaks through the tops of the trees, these growing conditions can be met just about anywhere, no matter which direction the surface faces.
Mosses need to grow in moist habitats because they are nonvascular plants, which means they do not have a network of vessels and roots to get water from the soil. Instead, they get water from their environment, as it passes over the plant.
Moss can grow anywhere that it is wet enough. Trees provide a good growing surface because tree bark usually has a lot of grooves and crevices, which are good places for moss spores to take root. Plus, not many other plants can grow on a vertical surface like a tree trunk, so they don't have to compete for a spot to grow.
Mosses use trees and other surfaces as a foundation to grow. They don't steal away water or nutrients, so they can grow on them without causing any harm. That’s why you often see big, healthy trees with trunks covered in fuzzy green moss.
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