Here's why:

* Xylem is a type of vascular tissue that runs throughout the plant, from the roots to the leaves. It acts like a system of tubes that transports water and dissolved minerals upwards.

* Phloem is the other type of vascular tissue, responsible for transporting sugars (food) produced during photosynthesis from the leaves to the rest of the plant.

So, the xylem brings the water the leaf needs for photosynthesis, and the phloem carries the food produced by the leaf to other parts of the plant.