Figure 1.

Growth-induced longitudinal tissue tension in a stalk of rhubarb. The red outer surface of the stalk grows slower than the green inner core and generates a state of surface tension and bulk compression. The balanced interplay between tension and compression gives the stalk its characteristic rigidity. When the surface layers are peeled off the inner core, they contract and bend outward, while the inner core expands as tissue tension is released. The release of tissue tension is associated with a significant loss of rigidity. (Adapted from [2].)