Study on adoptive feature of Hydrophytes (Water hyacinth)
Name of the specimen: Water hyacinth
Scientific name: Eichhornia crassipes
Ecological group: Hydrophyte
Subgroup: Free Floating Hydrophytes
Morphological Adaptive feature:
Root: Root system fibrous and adventitious with dense and adequate volume, which helps to maintain its balance with the aerial part. Root pocket present instead of root cap which protect roots from injury, holds the roots downward and act as water reservoir.
Stem: Modified into soft, succulent and cylindrical offset for its existence, growth and reproduction. It grows horizontally on water to minimize the extra load or imbalance of vertical growth.
Leaf: Simple and petiolate. The petiole characteristically becomes swollen at middle portion and develops sponginess which provides buoyancy to shoot. The lamina is medium, green, shiny and frequently coated with wax to prevent from decay under more water or extreme humid condition. Petiole becomes bulb like when free on water and slender at densely populated condition.
Anatomical adaptive features of offset:
- Epidermis is exposed i.e. cuticle absent which helps to absorb water and dissolved nutrients from the water body. Aerial parts contain cuticle as a fine film, which protect from outer hazards.
- Large numbers of air cavities are present which help the plants to float easily on water and store CO2 and O2 for physiological purposes.
- Mechanical tissue is absent which helps to show flexibility to survive on water.
- Vascular bundles are not well organized.
Anatomical Adaptive features of leaf petiole:
- Epidermis is naked.
- Large numbers of air cavities are present that separated from each other by one layer of parenchymatous cells. Then provide the buoyancy to the plant and store gases.
- Vascular bundles are poorly developed.
- Mechanical tissue is absent. Some calcium oxalate crystals present which are defense organ and may give a sort of mechanical support.
Anatomical adaptive features of leaf lamina:
- Thin cuticle is present on the leaf surface as a fine waxy film which protects the leaf from heat owing to high sunshine and from excessive transpiration.
- Both epidermal layers have well developed stomata but frequency is greater on the lower surface. It indicates that they require more transpiration.
- One to two layers of compacts palisade parenchymatous tissues are present at the upper surface which helps in structure formation and to protect the leaf from excessive transpiration.
- Vascular bundles is poorly developed which indicates less requirement of conduction.
Physiological adaptive features based on morphological and anatomical features:
- Absorb water and dissolved nutrients throughout the body remaining in contact with water.
- Water potential is very high as the concentration of their cell sap is very much close to surrounding water.
- Sub-aerial parts secrete mucilage substances to protect from decay the plant parts remaining under water.
- Transpiration rate is high compared to smaller hydrophytes as they have to absorb more water to accumulate nutrients from the water bodies.
- CO2 and light compensation points are low in compared to mesophytes.