A plant's sap is responsible for transporting sugars from the site of their manufacture (the leaves) to growth centers (further up the branch or trunk of the plant). And the system has to strike a delicate balance: if the sap has a low concentration of sugars, there isn't much energy flowing to the plant; if, on the other hand, there are lots of sugars in the sap it becomes too thick to pump efficiently. It's a situation a lot like transporting any payload through a traffic artery, be that a paved highway or a canal with kayakers. So what's in a plant's best interest?
Researchers reviewed 41 species of plants and found that, though most plants have sugar concentrations of 18 to 21 percent, the optimal sugar concentration is a bit higher: 23.5 percent. That's pretty sweet---twice as sweet as a Coke, for instance (10 percent sugar). At the other ...
