What are adaptations ? Describe the various adaptations plants to aquatic environment.

Explanation

Adaptation. N/A
Plant Adaptations to Aquatic Environment-Hydrophytes. Hydrophytes are of five types: submerged, suspended, free floating, floating leaved anchored and emergent hydrophytes. They possess special characteristics, (i) Mucilage. Hydrophytes are covered with mucilage which protects them from epiphytes, pathogens and animals. It also functions as lubricant, (ii) Roots. They are absent (e.g., Utricularia, Wolffia), poorly developed (e.g., Hydrilla, Vallisneria) or used for balancing (e.g., Lemna, Pistia, Eichhornia). Root hairs are absent or very few. Root caps are replaced by root pockets, (iii) Mechanical Tissue. It is absent, (iv) Xylem. It is poorly developed or absent, (v) Aerenchyma. Hydrophytes possess special air storage parenchyma called aerenchyma. It makes their different parts light, spongy and flexible. `O_(2)`, produced during photosynthesis, becomes available to roots and other nonphotosynthetic regions. It can also help in exchange of gases with the atmosphere through stomata present in emerged regions, (vi) Inflated Organs. Special air storing organs occur in floating plants, e.gi, roots in Ludwigia and petioles in Eichhornia. (vii) Leaves. Submerged leaves are thin, small, linear or finely dissected. Floating leaves are large, having stomata and waxy coating on the upper surface. Plants with both submerged and floating or emerged leaves show heterophylly or occurrence of more than one type of leaves, e.g., Ranunculus aquatilis, Sagittaria.