The arrangement of leaves on stem or its branches is called

Phyllotaxy is the pattern of arrangement of leaves on the stem or branch.

Vernation refers to the arrangement of young leaves in a bud while

The arrangement of veins and the veinlets in the lamina of leaf is termed as venation.

Heterophylly is the presence of differently shaped leaves on the same plant at the same or different nodes of a stem or branch.