What is the blade of a leaf?

The blade of a leaf refers to the broad, flat part of the leaf that is primarily responsible for photosynthesis. This structure is typically where the majority of chlorophyll is found, allowing the plant to absorb sunlight and convert it into energy. The blade's design usually maximizes surface area to capture as much light as possible while minimizing water loss.

The other options describe different features of a plant. The stem is a different structural element that supports the plant and transports nutrients and water. The tip of the root is also a distinct part that functions primarily in anchoring the plant and absorbing water and nutrients from the soil. The structure that carries water in plants refers to the vascular tissue known as xylem, which is distinct from the leaf blade itself. Hence, the definition of the blade accurately identifies it as the broad part of the leaf.