Petiole (botany)

[1]: 87 [2]: 171  It is able to twist the leaf to face the sun, producing a characteristic foliage arrangement (spacing of blades), and also optimizing its exposure to sunlight.

[1]: 87  There may be swollen regions at either end of the petiole known as pulvina (singular = pulvinus)[1]: 97  that are composed of a flexible tissue that allows leaf movement.

In some plants, the petioles are flattened and widened to become phyllodes (also known as phyllodia or cladophylls) and the true leaves may be reduced or absent.

In Acacia koa, the phyllodes are leathery and thick, allowing the tree to survive stressful environments.

In plants such as rhubarb (Rheum rhabarbarum), celery (Apium graveolens), artichokes, and cardoons (Cynara cardunculus), the petioles ('stalks' or 'ribs') are cultivated as edible crops.