Describe how xerophytes, mesophytes, hydrophytes and halophytes are adapted/ suited to their habitats.

a)Xerophytes (e.g. Aloe vera, Sisal, Cactus, Acacia)
-They have small and narrow leaves/needle-like leaves and spines; to reduce the surface area over which transpiration occur;
-The leaves have thick, waxy and shiny cuticle; to reflect away light reducing internal temperature of the leaf thus minimizing water loss/ reducing the rate of transpiration;
-The leaves have sunken stomata; which accumulate moisture in pits/depressions thus lowering the diffusion gradient reducing the rate of transpiration;
-Some have folded leaves; hence not exposing stomata to environmental factors thus reducing surface exposed reducing the rate of transpiration;
-Some xerophytes show reversed stomatal rhythm (they open the stomata during the night and close during the day); to prevent excessive water loss through transpiration during the day;
-Some xerophytes shed their leaves during drought; to reduce the surface area exposed to transpiration;
-Some have deep roots to absorb water from deep in the soil/ some have superficial roots (roots which grow horizontally close to the surface); to absorb water after light or short showers of rain;
-Some xerophytes have short life cycles; to escape drought;
-Some survive as seeds or underground storage organs;
-Xerophytes leaves and stems are succulent; (due to the presence of parenchyma cells) to store water which is used during drought;
-They have few/ reduced number of stomata; that lower the rate of transpiration;
-Have hairy leaves to trap moisture reducing concentration gradient hence reducing the rate of transpiration;
b)Mesophytes.
-The leaves have thin cuticle; to reduce the distance travelled by gases/ for faster diffusion of gases to the photosynthetic/palisade cells/ and increase the rate of transpiration;
 The leaves have broad lamina; to increase the surface area for absorption of light and carbon (IV) oxide and transpiration;
 They have mosaic arrangement of leaves; to avoid overlapping and over shadowing to increase the surface area for absorption of gases and light;
 They have stomata on the upper and lower leaf epidermis; for efficient gaseous exchange and transpiration.
 Their leaves have transparent cuticle and epidermal cells; to allow light penetration to the palisade cells and increase the rate of transpiration;
 Their leaves have air spaces in spongy mesophyll; for gases to diffuse easily into the palisade cells/ for efficient gaseous exchange;
 Palisade cells contain numerous chloroplasts; with chlorophyll next to the upper epidermis to receive maximum light for photosynthesis;
c)Hydrophytes
-Emergent and floating hydrophytes have broad leaves with numerous stomata on the upper surface; to increase the surface area for transpiration and for efficient gaseous exchange;
-Submerged hydrophytes have highly dissected leaves into thread-like straws; to increase surface area for absorption of maximum light and carbon (IV) oxide for photosynthesis and gaseous exchange;
-Floating hydrophytes have long fibrous roots; to absorb mineral salts dissolved in water;
-They have poorly developed roots that lack root hairs / poorly developed vascular bundle; to reduce absorption of water;
-They have aerenchyma tissue/ large air filled tissues; for buoyancy and for gaseous exchange;
-Flowers of emergent and floating hydrophytes are raised above the water; to allow pollination;
-The leaves of submerged hydrophytes have numerous and sensitive chloroplasts; that photosynthesize under low light intensities;
-Leaf lamina is thin; for faster diffusion of gases;
-Leaves lack cuticle; to allow for water loss;
d)Halophytes
-Their root cells have high salt concentration; to absorb water by osmosis;
-They have water storage tissues/ succulent tissues; that store water to dilute the cell cytoplasm;
-Some have salt glands on the leaves; to get rid/ remove excess salts;
-They have large air spaces/ aerenchyma tissue in their leaves, stems and fruits; to provide buoyancy and for gaseous exchange;
-Some hydrophytes e.g. mangrove have pneumatophores (breathing roots); for gaseous exchange;
-They have tissues which are tolerant to dehydration;
-Submerged halophytes have sensitive chloroplasts; which carry out photosynthesis under low light intensity;