Clubmoss (Selaginella selaginoides) stem. Light micrograph of a section through a stem from a lesser clubmoss plant, showing the central stele and outer layer of epidermis (dark red) with its cuticle. The stele consists of xylem tracheid cells, metaxylem and protoxylem cells (light red), and phloem sieve tube cells (pink). Magnification: x37 when printed 10 centimetres wide.