Hydrophytic plants (also called aquatic plants) live in or around water and have special leaf adaptations that help them survive in wet or submerged conditions. These modifications help them float, exchange gases, and perform photosynthesis efficiently.
Here’s how their leaves are modified for survival:
1. Thin and Broad Leaves
- Leaves are usually thin, flat, and broad to help them float and capture sunlight easily.
- Example: Lotus and Water lily have large circular leaves that float on the water surface.
2. Presence of Air Spaces (Aerenchyma)
- Leaves contain large air-filled spaces that make them light and buoyant.
- These air chambers also help in gas exchange between water and air.
- Example: Hydrilla and Vallisneria have air spaces in their tissues.
3. Reduced or Absent Cuticle
- Since they live in water, they don’t need to conserve moisture.
- Their leaves have a very thin or no waxy cuticle, allowing easy exchange of gases and water.
4. Stomata on Upper Surface Only
- In floating plants, stomata (tiny pores for gas exchange) are found only on the upper surface because the lower side is in contact with water.
- Example: Lotus and Nymphaea (water lily).
5. Submerged Leaves Are Finely Divided
- In plants that grow completely underwater, leaves are narrow and finely divided to reduce water resistance and allow easy movement of water around them.
- Example: Hydrilla, Ceratophyllum.
6. Lack of Mechanical Tissue
- Since water supports the plant body, mechanical tissues (for strength) are reduced or absent. This makes leaves soft and flexible.
7. Chloroplasts in Epidermis
- In some submerged plants, chloroplasts are present even in the epidermal cells to capture light efficiently in low-light underwater conditions.
In summary, hydrophytic plants modify their leaves to float, exchange gases easily, and perform photosynthesis efficiently in watery environments. These adaptations help them survive in conditions where air and sunlight may be limited.