Pulvinus

A pulvinus (pl. pulvini) is a joint-like thickening at the base of a plant leaf or leaflet that facilitates growth-independent movement. Pulvini are common, for example, in members of the bean family Fabaceae (Leguminosae)^[1]: 185 and the prayer plant family Marantaceae.^[1]: 381

Pulvini may be present at the base of the

Common examples for pulvinar movements include the night closure movement of legume leaves and the touch response of the sensitive plant Mimosa pudica. Sleep movements (nyctinastic movements) are controlled by the circadian clock and light signal transduction through phytochrome. Touch response (thigmonastic) movements appear to be regulated through electrical and chemical signal transduction spreading the stimulus throughout the plant.

Pulvinus in Mimosa pudica

In Mimosa pudica, the internal biological clock mediates the closing of leaflets at night and opening during day.^[2] Rapid (seismonastic) movement of leaves is triggered in response to touch and temperature.^[3]

A pulvinus is located at the base of each leaflet of the plant. Mechanical stimulation via touch is perceived and is translated to electrical stimulation causing the flow of ions out of the pulvinus cells.^[4] An upregulation^{[clarification needed]} of water channel proteins (aquaporins) and membrane proteins which move solutes across a cell membrane (H+ -

Using nuclear magnetic resonance, upward movement of water within the pulvinus joint in response to electrical stimulation was observed in the pulvinus at the base of the petiole (=the leaf stalk).^[9] Movement of water to the upper or lower part of the pulvinus causes asymmetric swelling, ^[9] therefore causing the stalk to either droop or rise.

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