(introduction...)

Pick up some leaves of a mango tree or coffee tree. Let us look at them.

· Leaves are usually of a green colour, more or less dark.
· They are joined to the stem by a stalk called the leaf- stalk.
· The leaf-stalk is continued into the leaf by the midrib.
· Other smaller veins branch out from the midrib. These are the primary and secondary veins.
· The whole flat part of the leaf is called the leaf blade or lamina.

A leaf