Question

Plants living partly inside water and partly above it are called:
A. Xerophytes
B. Thallophytes
C. Halophytes
D. Hydrophytes

Answer 1

Hint: Adaptations are the traits that increase an organism’s ability to survive in a particular environment. Plants show adaptations in accordance to their habitat. They exhibit entirely different environments, so are their adaptations.

Complete answer:
Due to availability of water, there are four types of plants:
1. Xerophytes
2. Halophytes
3. Mesophytes
4. Hydrophytes
Hydrophytes plants are the ones which are found in freshwater habitats. They are partially or completely submerged in water. They are either free floating or rooted. They have a soft body. Roots are either absent or poorly developed. Leaves which are above water contain stomata in the upper surface for transpiration. Example- Water lily, Vallisneria.
Plants living partly inside water and partly above it are called Halophytes. Halophytes plants are the plants which are growing in Salt marshes close to the sea. They have to absorb water from such soil which has higher salt concentration. Halophytes face this situation by actively salting into their roots as a result cells of roots develop lower water potential which brings in water by osmosis. These plants have salt glands on their leaves which helps in removal of excess water. Some Halophytes absorb humidity by leaves due to the concentration of salt in the leaves. Example- Mangrove, Cordgrass.
Mesophytes are the plants which grow on the soil which contain sufficient amounts of water. They can easily compensate for water loss by transportation through absorbing water from the soil. In order to prevent excess transpiration, these plants develop an external covering called cuticle.
Xerophytes are the plants which are adapted to live in dry habitats such as deserts. They are also called desert plants. They face shortage of water. In contrast to hydrophytes, Xerophytes have a very extensive root system. To reduce water loss through transportation, the leaves are reduced to spines. Eg. Opuntia.

So, the correct answer is ‘Halophytes’.

Note:
The adaptations may be structural, physiological, behavioral, or a combination of all these.
In some Xerophytes, leaves are totally absent thus their function is performed by stem. Eg. Casuarina.