hydrophytes — are plants that have adapted to living in or on aquatic environments. Because living on or under water surface requires numerous special adaptations, aquatic plants can only grow in water or permanently saturated soil. Aquatic vascular plants can be ferns or angiosperms. Seaweeds are not vascular plants but multicellular marine algae, and therefore not typically included in the category of aquatic plants. As opposed to plants types such as mesophytes and xerophytes, hydrophytes do not have a problem in retaining water due to the abundance of water in its environment. This means the plant has less need to regulate transpiration.
1. A thin cuticle. Cuticles primarily prevent water loss, thus most hydrophytes have no need for cuticles.
2. Stomata that are open most of time because water is abundant and therefore there is no need for it to be retained in the plant. This means that guard cells on the stomata are generally inactive.
3. An increased number of stomata, that can be on either side of leaves.
4. A less rigid structure: water pressure supports them.
5. Flat leaves on surface plants for flotation.
6. Air sacs for flotation.
7. Smaller roots: water can diffuse directly into leaves.
8. Feathery roots: no need to support the plant.
9. Specialized roots able to take in oxygen.