Pulvinus is the swollen leaf base seen in leguminous plants. Which option best describes this structure?

• A. Swollen leaf base in leguminous plants
• B. Flower stalk
• C. Root cap
• D. Node

Answer: (A)

Pulvinus is a swollen leaf base that acts as a flexible joint at the junction between the leaf (or leaflet) and the stem in leguminous plants. This swollen region contains specialized parenchyma whose cells change turgor pressure when ions move in or out, causing rapid water movement. That shift in turgor makes the pulvini bend, producing movements of the leaf such as nyctinasty (closing or drooping at night) or rapid folding in response to touch. So the description “swollen leaf base in leguminous plants” best captures both its location and its function. It isn’t a flower stalk, root cap, or node, which are different structures with other roles.