15 Difference Between Stomata And Hydathodes (With Pictures)

What Does Stomata Mean?

Stomate also referred to as Stoma, plural stomata or stomas , are any of the microscopic openings or pores in the epidermis  of leaves and young stems. The Stomata are generally more numerous on the underside of leaves. They provide for the exchange of gases between the outside air and the branched system of interconnecting air canals within the leaf.

The Stomata opens and closes in response to internal pressure of two sausage-shaped guard cells that surround it. The inner wall of a guard cell is thicker than the outer wall. When the guard cell is filled with water, it becomes turgid, the outer wall balloons outwards, drawing the inner wall with it and causing the stomata to enlarge. Guard cells work to control excessive water loss, closing on hot, dry, or windy days and opening when conditions are more favorable for gas exchange.

Types of stomata include:

• Actinocytic stomata: These stomata have guard cells that are surrounded by at least five radiating cells forming a star-like circle.
• Anisocytic stomata: These stomata have guard cells between two larger subsidiary cells and one distinctly smaller one.
• Anomocytic stomata: These stomata have guard cells that are surrounded by cells that have the same size, shape and arrangement as the rest of the epidermis cells.
• Diacytic stomata: Stomata have guard cells surrounded by two subsidiary cells, that each encycle one end of the opening and contact each other opposite to the middle of the opening.
• Hemiparacytic stomata: These Stomata are bordered by just one subsidiary cell that differs from the surrounding epidermis cells, its length parallel to the stoma opening.
• Paracytic stomata: These stomata have one or more subsidiary cells parallel to the opening between the guard cells. These subsidiary cells may reach beyond the guard cells or not.

What You Need To Know About Stomata

• Stomata are tiny pores or openings in plant tissue that allow for gas exchange. Stomata are typically found in plant leaves but can also be found in some stems.
• Stomata are found on the surfaces of the epidermis of the leaf and on the young parts of stems, fruits and flowers.
• Only water comes out in the form of vapor. No mineral salts are released with water.
• Stomata are surrounded by a pair of specialized epidermal cells referred to as Guard cells
• Stomata remain opened during the day time and closed during night time.
• The mechanism of opening and closing of stomata can be controlled by guard cells.
• Stomata are found in the aerial parts of all land plants.
• The guard cells surrounding the stomata contain chloroplast.
• Stomata do not have any functional relation with the vein ends of the leaves.
• Stomata are subtended by a sub-stomatal cavity. Epithem is not present.
• Stomata are involved in transpiration and exchange of gases.
• Stomata are usually enmeshed between many subsidiary cells.
• Stomata facilitate exchange of gases like oxygen and carbon dioxide.
• Types of stomata include: Actinocytic stomata, anisocytic stomata, anomocytic stomata, diacytic stomata, hemiparacytic stomata and paracytic stomata.

What Does Hydathode Mean?

A Hydathode is a type of pore, commonly found in angiosperms, that secretes water through pores in the epidermis or leaf margin, typically at the tip of a marginal tooth or serration. Hydathodes occur in the leaves of submerged aquatic plants as well as herbaceous plants of drier habitats. They are connected to the plant vascular system by a vascular bundle. Hydathodes are commonly seen in water lettuce, water hyacinth, rose, balsam, and many other species.

Hydathodes are made of a group of living cells with numerous intercellular spaces filled with water, but few or no chloroplasts, and represent modified bundle-ends. These cells referred to as epithem cells) open out into one or more sub-epidermal chambers. These, in turn, communicate with the exterior through an open water stoma or open pore. The water stoma structurally resembles an ordinary stoma, but is structurally larger and has lost the power of movement.

Hydathodes are involved in the process of guttation, in which positive xylem pressure (due to root pressure) causes liquid to exude from the pores. Hydathodes are of two types:

• Passive Hydathodes, formed when a leaf vein terminates in an epithem (an area of thin-walled parenchyma).
• Active Hydathodes, formed when epidermal cells lose water actively.

What You Need To Know About Hydathodes

• Hydathodes are specialized pores (openings) particularly present on leaf margins, which exude or secrete drops of water. Hydathodes are also referred to as Water Stomata.
• Hydathodes are found on the margins and tips of the leaves.
• Water along with mineral (inorganic) salts are released through the Hydathode pores in the form of liquid droplets.
• Hydathodes are surrounded by a ring of non-specialized cells.
• Hydathodes remain open both through daytime and night time.
• The closing and opening mechanism is absent in Hydathodes and therefore they remain always open.
• Hydathodes are present on the leaves of only a few plants.
• The cells surrounding the Hydathodes do not consist of chloroplast.
• Hydathodes have a functional relationship with the vein ends of the leaves.
• Hydathodes are subtended by a sub-epidermal cavity and a mass of loosely packed parenchymatous cells referred to as Epithem.
• Hydathodes are involved in guttation.
• The Hydathodes are surrounded with subsidiary cells.
• Hydathodes do not play any role in gaseous exchange in plants.
• There are only two types of Hydathodes, that is Active and passive Hydathodes.

Difference Between Stomata And Hydathodes In Tabular Form