Leaf Terminology
Botanists (plant scientists) count on differences in plants (leaf shape) to help them name and identify plants.

Leaf Structure
The blade is the entire leaf unit. Sometimes this is made up of several smaller leaflets.

The margin is the term used to describe the edge of the leaf.

Base is the name given to the part of the blade that is closest to the stem.

The Apex is the tip of the leaf.

The Petiole is the thin stalk that connects the leaf blade to the stem.

Stipules are tiny leaf-like structures that may or may not be present at the base of the petiole.

Leaflet

A leaf-like structure, but it's only part of a leaf. Green ash, horse chestnut, and Virginia creeper, for instance, have leaves made up of several leaflets.

Compound leaf   
This is a leaf that's made up of leaflets. The two most common types of compound leaf where the leaflets are arranged something like fingers around a hand and where the leaflets are arranged something like a feather.
 

Simple leaf

A simple leaf is one with no leaflets. An oak leaf is a simple leaf.
 

Margins:  the spacing between the teeth along the edge of the leaf blade.

To see pictures of these go to this website http://www.cas.psu.edu/docs/CASDEPT/Hort/LeafID/Margins.html

 

 

Leaf Arrangement

Opposite - directly opposite each other on the stem - on both sides, but not directly across from one another. Whorled - three or more leaves per node, usually opposite each other Basal - have no stem all leaves come from the base. Tulips have basal leaves.

 Leaf Veins support the leaf, carry water and nutrients to the leaf, and can appear in three forms.

parallel leaf veins
Parallel