Question
Answers

Leaves of submerged hydrophytes are
A. Epistomatic
B. Hypostomatic
C. Astomatic
D. Both A & B.

Answer
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Hint: Hydrophytes are plants growing in water. For example hydra
There are two types of hydrophytes :-
- Submerged hydrophytes: They have thin , long ribbon shaped leaves. They do not have stomata. They absorb water from their body surface . Their leaves are called astomatic as they do not have stomata. For example :- vallisneria
- Floating hydrophytes: Leaves of them are large, entire and flat . They are coated with wax . They have stomata on floating parts. For example :- Nymphaea.

Complete answer:
> Epistomatic: The leaf which has stomata on upper parts. These are present in nymphaea. So, the option is incorrect

> Hypostomatic: The leaf in which stomata are present on the lower side of the leaf. These are usually present in dicots. So, this option is also incorrect.

> Astomatic: The leaves which do not have stomata. This condition is found in submerged hydrophytes. So this option is correct.

> Both A and B: Epistomatic and hypostomatic leaf are present in floating hydrophytes and dicots respectively. Hence this option is wrong.

Hence, The correct answer is option (B).

Additional information:
Some adaptations found in hydrophytes are:
- Presence of large air spaces and aerenchyma
- Mechanical tissue that is sclerenchyma is poorly developed.
- Vascular tissue, especially xylem is poorly developed.
- Cuticles are absent.
- Epidermis is always single layered.

Note: Submerged hydrophytes do not have stomata on any portion of leaves. They do not have stomata in them. They absorb water through their general body surface. So they have astomatic leaves that means no stomata.