Reed, a tall grass that grows in marshy places and in shallow water in sluggish streams and ponds. It has a stout, woody stem and a thick network of roots. The giant reed, found in the Mediterranean region and in the southwestern United States, grows to a height of 20 feet (6 m). The stem is the source of the reeds used in the mouthpieces of certain woodwinds, such as clarinets. It is also used to make a type of wind instrument called the panpipe. The common reed, found throughout the world, grows to a height of 12 feet (3.7 m). Its stem is used in baskets and matting and, in Europe, to thatch roofs.

The giant reed is Arundo donax; the common, Phragmites communis. Reeds belong to the grass family, Gramineae.