Abstract
The leaf venation of dicotyledons form complex patterns. In spite
of their large variety of morphologies these patterns have common features.
They are formed of a hierarchy of structures, which are connected to form
a reticulum. Excellent images of these patterns can be obtained on
leaves from which the soft tissues have been removed. A numerical image
processing has been developed, specially designed for a quantitative analysis
of this type of network. It provides a precise characterization of
its geometry. The resulting data reveals a surprising property of
reticulum's node: the angles between vein segments are very well defined
and it is shown, that they are directly related by the radii of the segments.
The relation between radii and angles can be expressed in a very simple
way using a phenomenological analogy to mechanics. This local organization
principle is universal; all studied leaf venation patterns show the same
behavior. The results are compared with physical networks such
as fractures arrays or soap froth in terms of hierarchy and reorganization.