Fig. 5.3-12. Tangential section of wood of Zygogynum (no common name). The long cells here are fibers. Because they are part of the wood, they are xylary fibers (wood is a type of xylem called secondary xylem). These fibers are so fiber-like (long, thick walls, small pits) they are the type of xylary fiber known as libriform fibers.