The specialized cell types found in plant stems, leaves, roots, flowers, and fruits are organized into three tissue systems: the ground tissue system, the dermal tissue system, and the vascular tissue system. Each tissue system carries out a different general function: the vascular tissue system transports water and solutes over long distances within the plant, the dermal tissue system provides protection and gas exchange at the surface of the plant, and the ground tissue system provides cells that carry out photosynthesis, storage, and support. Each tissue system has many specialized cell types, and a few cell types are found in more than one tissue system.

Transmission electron micrograph of a parenchyma cell.

The different types of specialized plant cells are distinguished by cell shape and by properties of the cell wall and protoplast. The plant cell wall is one of the most important distinguishing...