1. (UsingCroizat's terminology, this network may be described as a “secundary” or “upper nerving center” of the phyllome.) Within the basis of petioles, just above the distal limitation of the leaf base, the partners of either of the lateral pairs of petiolar bundles join: Fusion of both partners of the outermost pair of bundles results in formation of the central bundle which dives down into the center of the petiole; it is to be considered the true or primary ventral median bundle. The next pair of bundles fuse, too, thus forming the adaxial bundle which actually is a secundary or false ventral median bundle. Both are completely inverted bundles. In this way, the number of originally formed seven main petiolar bundles is reduced to five.