A Unified Model of Shoot Tropism in Plants: Photo-, Gravi- and Propio-ception
Figure 1
Geometric description of organ shape.
The median line of an organ of total length L is in a plane defined by coordinates x, y. The arc length s is defined along the median line with s = 0 referring to the base and s = L referring to the apex. A(s) is the local orientation of the organ with respect to the vertical, and C(s) the local curvature. The orientation of the gravity field vector g is parallel to the y axis. The orientation of the light field vector l forms an angle AP with the y axis. The resulting angle of the two tropisms is called AR.