Moss: True North

I took a picture of this tree at high noon. Twelve o’clock. Why? To test an old piece of wilderness lore: the belief that moss grows on the north side of trees.

Does it? Or not? If you’re lost in the woods, should you look for moss on a tree trunk and set your path accordingly? Is this truth, or an old wives’ tale?

Every time I walk in the woods, I conduct a highly scientific survey on this topic–I glance at tree trunks from time to time. And I have conclusively proven beyond a shadow of a doubt that moss grows on trees.

But. Does it grow on one side more than on another? On the rare occasions that I actually know which direction I’m heading in, it does seem as though there’s kind of a lot of moss on the north sides. I’m more of an old wife than a scientist, so I tend to believe that there’s a strong bedrock of truth underneath most old tales and sayings and lore.

And as they say in the commercials, here’s scientific proof! Here’s a photo of the north side of the above tree. Moss.

Here’s a picture of the south side. No moss. (The blue-green stuff is lichen, not related to moss.) Case closed.

But alas, nothing is simple. Here’s a photo of the east side.

So here’s the deal. Moss can grow on any part of the tree, north, east, south, or west. However, moss is a plant that thrives in damp conditions. It needs water. The moss isn’t sucking water out of the tree, the moss depends on dew and rain to keep it alive. Moss needs moisture in order to live, make food, and reproduce.

Therefore, all things being equal, moss will tend to grow where there is most shade and therefore most moisture.

This tree is out in the open, with no other trees or buildings to shade it. The picture I took at noon shows that the north side is in shadow, the south side bathed in sun. So more moss will grow on the north, less on the south.

Moss grows on the north side of trees. It’s a tendency, not an absolute truth. But if you’re lost in the woods, you could do worse than follow the moss.