Trajectories of principal directions of growth, natural coordinate system in growing plant organ

Abstract

In symplasticly growing organs the principal directions of growth, which are indicated by the eigenvectors of the symmetric part of the growth tensor, can be associated with each positional point and joined up to form a network of orthogonal trajectories, unless the growth is isotropic. The trajectories represent a natural coordinate system suitable for description of growing organs. These trajectories often can be recognized in patterns of nonrandom alignments in the cell wall network: these alignments are normal to anticlinal and periclinal walls. Coordinate systems that fit the trajectories in different types of growing organ are listed.