Perennial Pastimes

I’d heard of a bee’s knees, but not a tree’s knees. Turns out cypress trees have knees, as we discovered when walking through the gardens at Historic London Town last weekend. We rounded a corner and stumbled upon an eerie landscape: a tall Bald Cypress tree surrounded by what looked like little stumps or treelets poking up from a blanket of leaves. It was almost as if we had been transported to the Island of Misfit Trees.

Turns out these little* woody projections are called cypress knees, and they are a bit of a mystery. The knees grow vertically from the tree’s roots, but no one quite agrees on what function they serve. Normally, they are found in swampy areas. This Bald Cypress and its knees were in Historic London Town’s Bog Garden–a very moist area, but not one that was under water (or at least not when we were there).  One theory is that the knees may help get oxygen to the tree’s roots, especially in the case of trees that are growing in several feet of water. But scientists who tested this theory found that the knees aren’t very good conveyors of oxygen, as one might expect from what is essentially a very woody stump. Another theory is that the knees provide the tree with stability. But no one really knows for sure; there is another school of thought suggesting that perhaps these knees serve no purpose at all…. Except to keep us wondering.

*These knees are still relatively little — but they can actually get quite tall.

Tags: Bald Cypress, bog, cypress, garden, Historic London Town, knees, Maryland, stump, swamp, Taxodium distichum, tree, trees, woody projection