Figure 7.

Growth-induced longitudinal tissue tension in a stalk of rhubarb. The stalk is modeled as a cylindrical tube with elastic volume elements and growing surface elements. With decreasing surface-to-volume growth ratios from $\widehat{\vartheta }=1.000$, to $\widehat{\vartheta }=0.980$, $\widehat{\vartheta }=0.960$, and $\widehat{\vartheta }=0.940$, the surface tension increases and induces a higher curvature when the stalk is cut in fourths. Red colors indicate compression, green and blue colors indicate tension.