What does pulvinus mean?
A pulvinus is a swollen, cushion-like structure at the base of a leaf stalk, or petiole, where the stalk joins the stem. It is especially associated with plants whose leaves can change position or fold in response to environmental conditions. In the sensitive plant, for example, movement at the pulvini causes the leaflets to close after a touch, while in other plants pulvini help leaves orient themselves in relation to light, temperature, and moisture. The term is chiefly used in botany and related scientific literature. Its name comes from Latin, where pulvinus meant a cushion or bolster. A pulvinus should not be confused with a pulvillus, which is a smaller pad-like or hair-like structure occurring in other botanical or anatomical contexts.
nounA cushion-like swelling at the base of a leaf stalk, or petiole, where it joins the stem. In some plants, pulvini allow the leaves to move in response to changes in light, temperature, or moisture.
- A cushion-like swelling at the base of a leaf stalk where it attaches to the stem, often serving as a flexible joint.
"The sensitive plant’s leaves fold when touched because movement occurs at the pulvinus at the base of each leaflet."
"The leaflets of the sensitive plant fold when touched because of the pulvinus at the base of each leaflet."
"Botanists examined the pulvinus under a microscope to understand how the plant changes the orientation of its leaves."
The standard plural is pulvini, referring to multiple pulvini.
"The plant uses pulvini to fold its leaflets when disturbed."
A pulvinus is a tiny natural hinge: it can help leaves fold, droop, or reorient themselves without the leaf stalk itself bending.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does pulvinus come from?
The word comes from Latin pulvinus, meaning “cushion” or “bolster.” Botanical writers adopted the term for the cushion-like swelling at the base of a petiole. The Latin root also underlies related terms such as pulvinar and pulvillus, although these have distinct meanings in different fields.
How pulvinus is actually used
This is a specialized botanical term used in formal scientific and horticultural writing. It is usually singular when referring to one structure and pulvini when referring to several.
Easily confused with pulvinus
A pulvinus is the swollen, joint-like base of a leaf stalk, whereas a pulvillus is a smaller pad-like or hair-like structure occurring in particular plants or anatomical contexts.