What Type of Cells Control Water Movement in Plants?

• Plants have sophisticated water control systems. Juergen Bosse/Photodisc/Getty Images

  Plants need water to conduct essential processes and survive. They have various cells controlling water movements within them. These cells obtain water, retain water within the plant, force water to travel along certain paths, distribute water and allow water to escape from the plant. Each type of cells has highly specialize functions.

Trichomes

• Trichomes, specialized epidermal cells on the outer layer of plant roots, extend to form root hairs. These root hairs, located near the growing tips of plant roots, serve to absorb water up plants. The small root hairs have a large surface area to maximize the amount of water absorbed.

Endodermis

• Plants have a layer of cells known as the endodermis that borders the inner part of the plant where the tubes that transport water around the plant is located and the outer part of the plant. Each cell in the endodermis is lined by a coating known as the Casparian strip, which prevents water from seeping between the cells. The Casparian strip forces water to travel only through some permeable cell membranes.

Vascular Tissue Cells

• The vascular tissue consists of xylem and phloem. These tiny tube structures distribute water and minerals throughout plants. The xylem, which transports water and minerals from the roots up to the leaves, consists of hollow, non-living cells. The phloem, which transports organic nutrients from the leaves to the roots, consists of living cells. Some phloem cells, known as sieve-tube cells, have sieve plates and no nucleus. Other phloem cells, known as companion cells, have a nucleus and are connected to sieve-tube cells.

Dermal Cells

• Dermal cells in the outer layer of the plant make up the dermal tissue. These cells, closely packed together, protect the plant. A waxy cuticle layer covers these cells, preventing water from seeping out of the plant. In this way, these cells minimize water loss and let the plant retain moisture.

Guard Cells

• Guard cells surround the openings in the epidermis of leaves and stems. These openings, known as stomata, allow oxygen and carbon dioxide in and out of the plant. They also allow water vapor to leave the plant. Each stomate has two guard cells that open and close the stomate. When they open, more water evaporates; when they close, less water evaporates.