Xylem cells are long and narrow, like pipes, and they carry water

When a tree is cut across, the xylem cells can be seen under a microscope. When cut that way, they look like small circles.

Xylem is a tissue in vascular plants. Its cells have thick, hard walls. Xylem tissue dies soon after it is formed and is the wood in the middle of a tree. The dead cells are like pipes, hollow and rigid.

Xylem is one of two tissues in the plant which transport substances that plants need to live. Substances that xylem transports include water and minerals obtained through the plant's roots, as xylem runs from the roots to the stems and leaves. The other transport tissue is the phloem, which transports energy in the form of sugar (as well as any other chemicals) from the leaves to the rest of the plant.