Hydrophytes
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This document discusses hydrophytes, which are plants that live fully or partially submerged in fresh water. It describes five categories of hydrophytes based on their relationship to water and air: free floating plants that float on the water surface and are not rooted; rooted floating plants with roots in the mud and leaves floating; submerged floating plants completely submerged with no contact with air or soil; rooted submerged plants completely submerged and rooted in soil; and amphibious plants adapted to both aquatic and terrestrial environments. Examples are given for each category. The document also summarizes anatomical adaptations of hydrophytes, such as thin leaves and stems, aerenchyma tissue for gas exchange, and poorly developed roots.
Hydrophytes
- 1. Hydrophytes Dr. Asmita Daspute. Assistant Professor, SBES College Aurangabad. India
- 2. Hydrophytes Hydrophytes are the plants which live completely or partially submerged in fresh water. Such plants do not face the problem of water shortage. They have developed mechanisms for the removal of extra water from their cells. Hydrophytes have broad leaves with a large number of stomata on their upper surfaces.
- 4. Hydrophytes The plants which are living in water or wet places are called hydrophytes. According to their relation to water and air, they are subdivided into following categories: i) Free floating hydrophytes, ii) Rooted- floating hydrophytes, iii) Submerged floating hydrophytes, iv) Rooted -submerged hydrophytes, v) Amphibious hydrophytes.
- 5. i. Free floating hydrophytes: These plants float freely on the surface of water. They remain in contact with water and air, but not with soil. Examples: Eichhornia, Pistia and Wolffia (smallest flowering plant).
- 6. ii. Rooted floating hydrophytes: In these plants, the roots are fixed in mud, but their leaves and flowers are floating on the surface of water. These plants are in contact with soil, water and air. Examples: Nelumbo, Nymphaea, Potomogeton and Marsilea. Lotus seeds show highest longevity in plant kingdom.
- 7. iii. Submerged floating hydrophytes: These plants are completely submerged in water and not in contact with soil and air. Examples: Ceratophyllum and Utricularia. iv. Rooted- submerged hydrophytes: These plants are completely submerged in water and rooted in soil and not in contact with air. Examples: Hydrilla, Vallisneria and Isoetes.
- 8. v. Amphibious hydrophytes (Rooted emergent hydrophytes): These plants are adapted to both aquatic and terrestrial modes of life. They grow in shallow water. Examples: Ranunculus, Typha and Sagittaria.
- 9. EcologicalAdoptationsinHydrophytes: A. Roots: 1. Due to availability of plenty of water root system is secondary importance and least significant. 2. Roots absent in Wolfia, Ceratophylum. 3. Poorly developed roots are seen in Hydrilla. 4. Submerged leaves compensate for roots in Salvania. 5. Root caps are absent in Hydrophytes. 6. Amphibious plants growing in mud will have distinct root caps. 7. Root caps are replaced by root pockets in Pistia.
- 10. A. Roots:
- 11. stem • The stem is long, slender, spongy and flexible in submerged forms. • In free floating forms the stem is thick, short stoloniferous and spongy; and in rooted f loating forms, it is a rhizome. • Vegetative propagation is through runners, stolon, stem and root cuttings , tubers, dormant apices and offsets.
- 12. leaves • The leaves are thin, long and ribbon shaped in Vallisneria or long and linear in Potamogeton or finely dissected in Ceratophyllum • The floating leaves are large and flat as in Nymphaea and Nelumbo. In Eichhornia and Trapa petioles become swollen and spongy. • In emergent forms, the leaves show heterophylly (Submerged leaves are dissected and aerial leaves are entire). Example: Ranunculus, Limnophila heterophylla and Sagittaria
- 14. Anatomical adaptations • Cuticle is either completely absent or if present it is thin and poorly developed • Single layer of epidermis is present • Cortex is well developed with aerenchyma • Vascular tissues are poorly developed. In emergent forms vascular elements are well developed. • Mechanical tissues are generally absent except in some emergent forms. Pith cells are sclerenchymatous.