Venation
The venation, or veining, of leaves relates to the mode in which the woody tissue, in the form of ribs, veins, etc., is distributed in the cellular tissue.
There are two principle modes—
the parallel-veined, of which the iris is an example;
the reticulated-veined, or netted-veined, of which the Elm is an example.
Small veins are called veinlets.