This summer, while wandering through the beautiful VanDusen Gardens in Vancouver, British Columbia, I saw the remarkable bald cypress, complete with knees. I had written a short post on Deciduous Conifers previously, and had always wanted to see this tree, and especially those knees! There are theories swirling all around about the purpose of the knees. Could these projections of the roots act as a support and stabilization for trees that grow near water? That seems a likely theory. Or perhaps they aid in oxygen absorption? Possibly. Others theorize that the knees provide nutrients to the tree. Hmmm, maybe. Well, I have a few theories of my own:*
1. As the knees rise up through the soil they aerate and loosen the dirt, providing a healthier environment for beneficial microbes which help the tree grow. Go mycorrhizae!
2. The projections surround the tree like a barricade, creating a defense or fortification against browsing animals and unwelcome intruders. Booby-traps to trip the unwary.
3. Taxodium was jealous of Metasequoia who has armpits, so it grew knees. Much more elegant.
4. The knees are allelopathic, secreting a secret substance around the base of the tree and inhibiting germination of unwanted plants. No competition allowed.
5. These attractive knobs are really a distraction and a diversion from the real show which is happening in the treetops. The tree wants us to keep our eyes on the ground, focused on these lovely little bumps instead of looking up to where the real activity is taking place. Unfortunately for us, the tree has succeeded and no one knows what’s going on in the leafy treetops because we’re ogling the knees all the time. You won this one tree!
6. Living furniture. The forest gnomes and fairies have created tiny seats by using their woodland magic to call up the knees out of the earth. You can often find remnants of pixie dust on the bark.
7. Communication. The tree is sending up the knees in a complex mathematical pattern, which, if we could only interpret it, would probably be a profound message from the universe. Alas, at this point in our evolution it’s way beyond our understanding.
8. Tree song. When centered in the middle of the knees, very close to the trunk, a person can sing the tree song of an individual Taxodium by reading the knee notes, indicated by the height and width of the knees. Unfortunately this type of music has been lost to modern scholars. Only a few existing tree notes have been preserved and these are etched into a fossilized knee found in the swamps of South Carolina. Do re mi fa so la tree do!
9. Tree fun. It just feels good. Vanity. It just looks good.
10. Lighting. The bio-luminescent algae from the swamp form a symbiotic relationship with the Taxodium knees, creating a soft evening glow to light the way for the nesting warblers which carve their home into the knees, keeping them free of bothersome pests. The circle of life.
*All theories are based on a complete lack of evidence and the wild imagination of the author.
Just the Facts
Taxodium distichum Bald Cypress
50-70′ (15-21m) High 20-30′ (6-9m) Wide
Deciduous conifer of pyramidal habit
Attractive reddish brown fibrous bark
Grows best with plenty of moisture, but adaptable to many soil conditions. Grows in swamps in its natural habitat
When planted by water, knees will form in the shallow water at the lake’s edge and seldom on the land side.
‘Peve Minaret’ is a variety with a tight, upright dense habit to 10 feet (3m). Closely spaced needles and large fattened trunk on small tree create a beautiful specimen. Easily pruned.