Some aquatic plants do transpire, but the extent depends on whether they are submerged or emergent. Submerged aquatic plants typically have reduced or absent transpiration, while emergent aquatic plants transpire like terrestrial plants.
Transpiration in Submerged Aquatic Plants
Submerged aquatic plants generally do not exhibit significant transpiration. This is primarily because:
- Lack of Stomata: Many submerged plants lack stomata, the pores on leaves that regulate gas exchange and water loss in terrestrial plants. They absorb nutrients and gases directly from the surrounding water through their leaf surfaces.
- Diffusion: Gaseous exchange occurs through diffusion across the leaf surface.
- Cuticle Reduction or Absence: Submerged plants often have a reduced or absent cuticle (the waxy outer layer), which minimizes water loss but also makes transpiration less necessary.
Transpiration in Emergent Aquatic Plants
Emergent aquatic plants, which have leaves that extend above the water surface, do transpire. They possess stomata and a cuticle, similar to terrestrial plants, and therefore experience water loss through transpiration. Examples include:
- Water lilies: Their leaves float on the water's surface and have stomata on the upper surface for transpiration.
- Cattails and Reeds: These plants grow with their roots submerged but their stems and leaves in the air, allowing for transpiration to occur.
Summary Table
| Plant Type | Transpiration | Stomata Presence | Cuticle Presence |
|---|---|---|---|
| Submerged Aquatic | Reduced/Absent | Absent/Reduced | Absent/Reduced |
| Emergent Aquatic | Present | Present | Present |
Conclusion
While submerged aquatic plants minimize or eliminate transpiration due to their adaptation to a water-rich environment, emergent aquatic plants do transpire as their leaves are exposed to the air.
