What is the swollen leaf base called in some leguminous plants?

• A. Axillary Bud
• B. Leaf Base
• C. Petiole
• D. Pulvinous

Answer: (D)

The swollen leaf base in many leguminous plants is called the pulvinus. This is a specialized, joint-like region at the base of the leaf or leaflet that becomes turgor-driven and can change its water content quickly. By losing or gaining water on one side, cells cause the leaf to bend or rotate without growth, enabling movements like closing or folding of the leaf in response to light, touch, or gravity. This pulvinar tissue is what allows rapid, reversible leaf movements, a feature particularly notable in legumes. Other terms describe different parts or functions—an axillary bud is a potential new shoot in the leaf axil, the leaf base is a generic term, and the petiole is simply the leaf stalk—whereas the pulvinus is the specialized swollen base that drives movement.