Companion cells in plants are associated with

The companion cells occur only in angiosperms where they accompany most sieve tube elements. Companion cell is a speciliased type of parenchyma cell which is closely associated in origin, position and function with sieve tube elements. These cells are living having abundant granular cytoplasm and a prominent elongated nucleus. Usually, the nuclei of the companion cell serve for the nuclei of the sieve tubes as they lack them. The companion cells do not contain starch. They live only so long as the sieve tube element with which they are associated and they are crushed with those cells. Longitudinal division of the mother cell of the sieve tube element forms the companion cells. One daughter cell becomes a companion cell and other sieve tube element.