Explain the adaptation characteristics of hydrophytes, halophytes and xerophytes from the aspects of: (i) intake of water and mineral salts. (ii) gas exchange. (iii) support. (iv) photosynthesis

Adaptations of Plants

7.1

Adaptation of Plants

Adaptation

Adaptation is the adjustment of an organism to the environment.
All organisms adapt.
Animals and plants have unique structures and shapes to adapt to the environment to ensure the survival of the species.
For a plant, this adaptation can be observed in the shape of its leaves, roots, and stem, to adjust itself to live in its habitat.

Classification of Plants based on Habitats

Halophytes

Plants that live in swampy habitats at the river mouth, the meeting point of fresh water and seawater. This swampy area is rich in salt content.
Example:
- Avicennia sp.
- Sonneratia sp.
- Rhizophora sp.
- Brugeria sp.
- Pandanus sp.
- Nyla sp.

Mesophytes

Plants that live in a habitat that is not too dry nor too wet with an adequate supply of water.
Most plants are mesophytes.
Example:
- Helianthus sp. (Sunflower).
- Zea mays (Maize).
- Musa sp. (Banana).
- Durio sp. (Durian).

Hydrophytes

Plants that live in aquatic habitats, either on the water surface or submerged in the water.
Example:
- Hydrilla sp.
- Elodea sp.
- Uticularia sp.

Xerophytes

Plants that live in a habitat that is hot and dry with a minimum presence of water, that is, a place with very high temperatures such as the desert.
Example:
- Cactus.
- Pineapple.
- Pine trees.

Characteristics of Diferent Habitats
Types of Plants based on Habitat	Chracteristics of Habitat
Mesophyte	Optimum temperature. Sufficient water supply. Optimum air humidity. Appropriate soil texture.
Hydrophyte	High temperature at water surface. Sufficient water supply. High air humidity. Muddy soil.
Halophyte	High temperature. Insufficient of fresh water supply. Concentration of mineral salts in water is higher and changes. High air humidity. Sandy soil.
Xerophyte	High temperature. Lack of water supply. Very low air humidity. Dry soil.

Adaptive Features of Plants based on Different Habitats

Hydrophytes

Structure	Adapative Features	Explaination
Leaf	Cuticle is absent in leaves of submerged plants. Stomata are absent in leaves of submerged plants. Stomata are only present on upper epidermis of leaves in floating plants. The upper leaf surface in floating leaves are coated with waxy cuticle.	Submerged plants have no stomata. Gaseous exchange for submerged plants is through diffusion of gases in water.
Stem	Presence of aerenchyma tissue to have air spaces. Vascular tissues are poor developed.	To float plants. To absorb water and minerals by osmosis.
Root	Roots are poorly developed.	Roots that anchor the soil is not necessary.
Reproduction	Reproduction is mainly by asexual methods. The flowers and seeds are less abundant.	Pollination seldom or unavailable under water.

Halophytes

Structure	Adaptive Features	Explaination
Leaf	Thick cuticle is present in the epidermal layer. Sunken stomata are present. Leaves are succulent. Salt glands are present on the leaf margin.	To conserve water. To store water. To remove excess salt from plants.
Stem	Stems are hard woody and covered with thick bark. Vascular tissues are well developed.	For support. To transport water and minerals.
Root	The roott systems are well developed with prop roots,cable roots,buttress roots or pneumatophores.	To anchor muudy soil firmly. For gases exchange.
Reproduction	Viviparous seeds.	Enable seedlings to be survived.

Xerofphytes

Structure	Adaptive Features	Explaination
Leaf	Thick cuticle is present in the epidermal layer. Sunken stomata are present. Leaves are succulent or rolled. The stoma open during night-time and remain close during day-time. Leaves are reduced in size or needle-like.	To conserve water. To store water.
Stem	Stems are succulent or woody and covered with thick. bark Vascular tissues are well developed.	To store water. To transport water effectively.
Root	The root systems are well developed,elongated with root hairs.	To absorbs and pending sources of water and mineral salts.
Reproduction	Sexual and asexual reproduction.	To increase the survival of species.

Adaptations of Plants

7.1

Adaptation of Plants

Adaptation

Adaptation is the adjustment of an organism to the environment.
All organisms adapt.
Animals and plants have unique structures and shapes to adapt to the environment to ensure the survival of the species.
For a plant, this adaptation can be observed in the shape of its leaves, roots, and stem, to adjust itself to live in its habitat.

Classification of Plants based on Habitats

Halophytes

Plants that live in swampy habitats at the river mouth, the meeting point of fresh water and seawater. This swampy area is rich in salt content.
Example:
- Avicennia sp.
- Sonneratia sp.
- Rhizophora sp.
- Brugeria sp.
- Pandanus sp.
- Nyla sp.

Mesophytes

Plants that live in a habitat that is not too dry nor too wet with an adequate supply of water.
Most plants are mesophytes.
Example:
- Helianthus sp. (Sunflower).
- Zea mays (Maize).
- Musa sp. (Banana).
- Durio sp. (Durian).

Hydrophytes

Plants that live in aquatic habitats, either on the water surface or submerged in the water.
Example:
- Hydrilla sp.
- Elodea sp.
- Uticularia sp.

Xerophytes

Plants that live in a habitat that is hot and dry with a minimum presence of water, that is, a place with very high temperatures such as the desert.
Example:
- Cactus.
- Pineapple.
- Pine trees.

Characteristics of Diferent Habitats
Types of Plants based on Habitat	Chracteristics of Habitat
Mesophyte	Optimum temperature. Sufficient water supply. Optimum air humidity. Appropriate soil texture.
Hydrophyte	High temperature at water surface. Sufficient water supply. High air humidity. Muddy soil.
Halophyte	High temperature. Insufficient of fresh water supply. Concentration of mineral salts in water is higher and changes. High air humidity. Sandy soil.
Xerophyte	High temperature. Lack of water supply. Very low air humidity. Dry soil.

Adaptive Features of Plants based on Different Habitats

Hydrophytes

Structure	Adapative Features	Explaination
Leaf	Cuticle is absent in leaves of submerged plants. Stomata are absent in leaves of submerged plants. Stomata are only present on upper epidermis of leaves in floating plants. The upper leaf surface in floating leaves are coated with waxy cuticle.	Submerged plants have no stomata. Gaseous exchange for submerged plants is through diffusion of gases in water.
Stem	Presence of aerenchyma tissue to have air spaces. Vascular tissues are poor developed.	To float plants. To absorb water and minerals by osmosis.
Root	Roots are poorly developed.	Roots that anchor the soil is not necessary.
Reproduction	Reproduction is mainly by asexual methods. The flowers and seeds are less abundant.	Pollination seldom or unavailable under water.

Halophytes

Structure	Adaptive Features	Explaination
Leaf	Thick cuticle is present in the epidermal layer. Sunken stomata are present. Leaves are succulent. Salt glands are present on the leaf margin.	To conserve water. To store water. To remove excess salt from plants.
Stem	Stems are hard woody and covered with thick bark. Vascular tissues are well developed.	For support. To transport water and minerals.
Root	The roott systems are well developed with prop roots,cable roots,buttress roots or pneumatophores.	To anchor muudy soil firmly. For gases exchange.
Reproduction	Viviparous seeds.	Enable seedlings to be survived.

Xerofphytes

Structure	Adaptive Features	Explaination
Leaf	Thick cuticle is present in the epidermal layer. Sunken stomata are present. Leaves are succulent or rolled. The stoma open during night-time and remain close during day-time. Leaves are reduced in size or needle-like.	To conserve water. To store water.
Stem	Stems are succulent or woody and covered with thick. bark Vascular tissues are well developed.	To store water. To transport water effectively.
Root	The root systems are well developed,elongated with root hairs.	To absorbs and pending sources of water and mineral salts.
Reproduction	Sexual and asexual reproduction.	To increase the survival of species.