blade 
Main part of the leaf, rich in chlorophyll; it can vary markedly in shape, depending on the type of rib and size of indentation.
tip 
Apex of the leaf blade, at the opposite end from the part attached to the petiole; this part can vary markedly in shape.
midrib 
Hollow projection that extends the petiole into the blade and carries sap; it forms the basis of the leaf’s skeleton.
vein 
Branching of the midrib that carries sap to the various parts of the blade; it also functions as the leaf’s skeleton.
sheath 
Distension of the petiole, partly or completely surrounding the stem.