Question

From epithem hydathodes, the water comes out due to:
A. Imbibition pressure
B. Osmotic pressure
C. Root pressure
D. All off the above

Answer 1

Hint: A Hydathode is a type of pore that is mostly found in Angiosperms which helps in secreting water through pore. Hydathode is present on the edge of the leaves. It is involved in guttation. During the guttation the positive root pressure forces water to come out from the epithem hydathode in the form of drops.

Complete Answer:
- Hydathodes are the secretory tissue that helps in the process of guttation. They are connected to a plant vascular system by vascular bundle.
- They are made of a group of living cells having numerous intercellular spaces filled with water. The cells are known as epithem cells which open out into one or more sub-epidermal chambers and communicate to the exterior through open pore.
- Guttation is the process of loss of water in the form of water droplets with the help of hydathodes on the leaf margin of a plant. The hydathodes are involved in the process of guttation with the help of root pressure that causes liquid to exudate from the pores.
Hydathodes are of 2 types
A. Passive – forms when a leaf vein terminates in an epithem.
B. Active – forms when epidermal cells lose water actively.
Hydathodes are commonly seen in water lettuce, rose, balsam and many other species.

So the correct answer is Root pressure.

Note: The stomata are present on the epidermis of leaf, young stem while the hydathodes are present on the margins of leaf.