Jan 30 2009
The Mystery of Tree Knees
What are those odd growths among the cypress trees? They are called knees, and are found around trees in swampy areas. Years ago I had learned that their purpose was to provide oxygen when the water level rises, as it does around here after any significant rainfall. But I may have learned something untrue. I just checked Wikipedia and found this -
Knees are woody projections sent above the normal water level, roughly horizontally from the roots, with a near-right-angle bend taking them roughly vertically downward into soil, usually passing through water first. One rather popular view of their function is that they provide oxygen to the roots that grow in the low dissolved oxygen (DO) waters typical of a swamp (see also mangroves, which have similar adaptations). However, there is little evidence for this; in fact, swamp-dwelling specimens whose knees are removed continue to thrive.
Damn. Scientists know how to build a reactor that sends protons crashing into one another in a spray of quarks, but “they” don’t know why a cypress tree has knees. Maybe very few are drawn to that particular field of study. Or maybe it’s a swamp of study.
