Trees with Knees

Cupressaceae, the conifer family, includes some of the world’s most ancient trees, some dating back to over 150 million years ago. Famous members of this family include the coastal redwood, giant sequoias, and bald cypress. The redwoods and sequoias certainly have their claim to fame, but what is so special about bald cypress trees?

In addition to the bald cypress being the state tree of the beautiful state of Louisiana and being exceptionally well adapted to moist environments, these trees have unique features at their trunks. Figure 1 shows knob-like structures, called knees, protruding from the near the base of the cypress. Knees are commonly seen growing out of shallow water banks or supersaturated soil.

Christopher H. Briand published “Cypress Knees: an Enduring Enigma” after inspecting over 200 years of investigations. His thorough analysis can be found here (http://arnoldia.arboretum.harvard.edu/pdf/articles/2000-60-4-cypress-knees-an-enduring-enigma.pdf); Spoiler Alert! There is no known purpose to cypress knees! It’s been thought that the knees aid in collecting oxygen, nutrients, or storing carbohydrates. The knees may also provide a mechanical function, further anchoring these swamp trees into the muddy soil. Eventually, each of these theories was debunked by laboratory analysis or on-site knee removal.

These trees play an instrumental role in mitigating soil erosion and floodwaters. If they want to keep their knees a secret, let them for now.

Do you have a theory? Share it below!

Related Articles

Responses

Your email address will not be published. Required fields are marked *

Want to learn more about your local community forest?

Join Us
LOGO

American Grove is an online community for sharing knowledge, experience, and insights about the trees and forests that enrich our cities, towns, and neighborhoods nationwide.

Group logo of Great American Tree
Group Highlight Great American Tree
Member Highlight Morgan Garner
My love for the environment has fueled my career as a physical scientist. I am…
Would you like to leave feedback or have a question? Email us, click here.
Skip to toolbar