A pulvinus (pl. pulvini) is a joint-like thickening at the base of a plant leaf or leaflet that facilitates growth-independent (nyctinastic and thigmonastic) movement. Pulvini are common in members of the bean family Fabaceae (Leguminosae) and the prayer plant family Marantaceae. Pulvini may be present at the base or apex of the petiole or where the leaflets of a compound leaf are inserted into the rachis. They consist of a core of vascular tissue within a flexible, bulky cylinder of thin-walled parenchyma cells. A pulvinus is also sometimes called a geniculum.