Simple leaves are single, undivided blades. Therefore, structures associated with compound leaves are not found in simple leaves. These include:

* Petiolules: Small stalks attaching leaflets to the rachis.

* Rachis: The central axis of a compound leaf, to which leaflets are attached.

* Leaflets: Individual, smaller blades that make up a compound leaf.

Additionally, simple leaves may lack structures found in complex leaves, such as:

* Stipules: Small leaf-like appendages found at the base of the petiole.

* Tendrils: Modified leaf parts that help the plant climb.

It's important to note that simple leaves can still have veins, a petiole, and a blade like any other leaf.