Unidirectional wind stimulates the development of flag forms in trees.

Mango tree show very narrow range of thermal tolerance. Hence they cannot grow in temperate countries.

Anatomical adaptations:
1. Epidermal cells of stem is heavily cutinized, almost squarish and are filled with oil and tannins.
2. 'Star' shaped sclereids and 'H' shaped heavy thickened spicules that provide mechanical strength to cortex are present in the stem.
3. The leaves may be dorsiventral or isobilateral with salt secreting glands.

Physical dryness: In these habitats, soil has a little amount of water due to the inability of the soil to hold water because of low rainfall.
Physiological dryness: In these habitats, water is sufficiently present but plants are unable to absorb it because of the absence of capillary spaces. Example: Plants in salty and acidic soil.

The interaction between organisms, when continues for generations, involves reciprocal changes in genetic and morphological characters of both organisms. This type of evolution is called Co-evolution. It is a kind of co-adaptation and mutual change among interactive species.
Examples:
1. Corolla length and proboscis length of butterflies and moths (Habenaria and Moth).
2. Bird's beak shape and flower shape and size.

(a) Carausium morosus (Stick insect)
(b) Phylliumfrondosum (Leaf insect).

Predation: It is an interaction between two species, one of which captures, kills and eats up the other. The species which kills is called a predator and the species which is killed is called a prey. The predator is benefitted while the prey is harmed.
1. Many herbivores are predators. Cattles, Camels and Goats etc., frequently browse on the tender shoots of herbs, shrubs and trees.

The plants which are found growing on other plants without harming them are called epiphytes. They are commonly found in tropical rain forest.
The epiphytic higher plant (Orchids) gets its nutrients and water from the atmosphere with the help of their hygroscopic roots which contain special type of spongy tissue called Velamen. So it prepares its own food and does not depend on the host. They use the host plant only for support and does not harm.

North and south faces of mountain or hill possess different types of flora and fauna because they differ in their humidity, rainfall, light intensity, light duration and temperature regions. The two faces of the mountain or hill receive different amount of solar radiation, wind action and rain. Of these two faces, the windward region possesses good vegetation due to heavy rains and the leeward region possesses poor vegetation due to rain shadows (rain deficit).

Loamy soil is ideal soil for cultivation, since it consists of 70% sand and 30% clay or silt or both. It ensures good retention and proper drainage of water. The porosity of soil provides adequate aeration and allows the penetration of roots.

Based on soil formation (pedogenesis), the soils are divided into:
1. Residual soils -These are soils formed by weathering and pedogenesis of the rock.
2. Transported soils - These are transported by various agencies.

1. Ground fire - Which is flame less and subterranean.
2. Surface fire - Which consumes the herbs and shrubs.
3. Crown fire - Which burns the forest canopy.

1. Temperature affects the enzymatic action of all the bio-chemical reactions in a plant body.
2. Low temperature with high humidity can spread diseases to plants.
3. The varying temperature with moisture determines the distribution of the vegetation types.

Thermal stratification is usually found in aquatic habitat. The change in the temperature profile with increasing depth in a water body is called thermal stratification. There are three kinds of thermal stratifications.
1. Epilimnion - The upper layer of warmer water.
2. Metalimnion - The middle layer with a zone of gradual decrease in temperature.
3. Hypolimnion - The bottom layer of colder water.