What are some differences between the xylem and the phloem S

What are some differences between the xylem and the phloem?

Solution

Xylem is a complex tissue that conducts water and minerals from roots to all plant parts. The xylem contains cells like vessels, tracheids, fibers and parenchyma. Vessels are the long tubes made up of small vessel members that are joined end to end at the walls. The tracheids are long and dead cells with tapered ends and conduct the water through pits. Tracheids are chief cells providing strength and support in the stems of gymnosperms. The fibers are thick walled cells made up of sclenrenchyma and provide the support. The parenchyma cells in the xylem useful for the storage. The movement of water and minerals through the xylem is a physiological process.

The thickness of xylem is greater than phloem. xylem is located at the center of vascular bundles and phloem is at outer side. The xylem expands in thickness as the plants grow. The cellwalls of xylem cells are thicker than phloem cells. The size of cells vary in xylem and phloem depending on the type of plant.

Phloem is a complex tissue that conducts food and metabolites from leaves to stem, flowers, roots and the storage organs. It comprises of sieve tubes, sieve tube members, companion cells, fibers and the parenchyma. The sieve tube members are long and slender cells with porous ends known as sieve plates. The sieve tube members occur only in angiosperms and sieve cells are the equivalent cells occurring in the gymnosperms. The sieve tube elements in gymnosperms are similar to angiosperms except lacking the sieve plate.

The companion cells are useful for conduction of metabolites under closely associated with sieve tube members. The phloem fibers have thick walled cells and provide support to the stems. The parenchyma cells act as storage sites and are made up of hollow tubes produced from dead cells. The phloem contains living cells and conduction of food and metabolites is a biological activity.