10X THE SPEED OF Blood in Your veins

Flows for a deciduous tree such as an oak . . . run up to roughly 40 meters per hour, or about 10 millimeters per second. That’s an inch every two and a half seconds, more than ten times the speed with which blood is flowing through your capillaries as you quietly read this.

(The Life of a Leaf, Steven Vogel; University of Chicago Press, 2012. Pg. 111)

To view the annotated version of the video above, hover on the control bar at bottom and click on the CC icon.


by GFB after reading Vogel’s Life of a Leaf

Leaves work very hard to manage their internal temperatures, which fluctuate wildly. Leaves have numerous ways to avoid too much solar. Yes, too much solar is not a good thing and leaves overheat.

One way to manage overheating is to produce both sun leaves and shade leaves. You may have noticed that not all of a tree’s leaves look the same – that’s why. The sun leaves are those at the top and outermost edges of the tree’s canopy where there is greater solar. The shade leaves are in a more protected position and are larger because they are out of direct sun. Every year a tree determines what leaves will be sun leaves, and what leaves will be shade leaves. The tree is responding to its environment. What if a companion tree has been removed, or a large building erected? The tree can create a shade leaf in exactly the same spot that it made a sun leaf the year before and visa-versa.

The leaf’s choice is based on managing its solar input; it is not genetic. Sadly, trees are defenseless against pruning shears and saws. Cutting away branches during a tree’s leafy season upsets the balance and throws the leaves into distress mode as shade leaves are no longer protected and the larger surfaces suddenly have too much solar. Removing leafy twigs and branches also means decreased photosynthesis and less food to send to the tree’s roots. There is a very complex working relationship between the leaves and the roots. Together they provide for the tree’s sustenance and success in life.