In xerophytic plants, with the leaves and stem are covered with hairs are called trichophyllous plants. Example: Cucurbits (Melothria and Mulda)

Commensalism is an interaction between two organisms in which one is benefitted and the other is neither benefitted nor harmed. The species that derives benefit is called the commensal, while the other species is called the host.

The environment (surrounding) includes physical, chemical and biological components. When a component surrounding an organism affects the life of an organism, it becomes a factor. All such factors together are called environmental factors or ecological factors.

Certain plants can also be used to remove cadmium from contaminated soil, this is known as phytoremediation.
Example: Eichhornia

Taxonomically different species occupying similar habitats (Niches) in different geographical regions are called Ecological equivalents.
E.g: Certain species of epiphytic orchids of Western Ghats of India differ from the epiphytic orchids of South America. But they are epiphytes.

The letter C denotes Ecotone - a transition zone between two different ecosystem. Those species found in the ecotone will have impact of environment of two habitats. E.g. Owl in the ecotone area between forest and grassland.

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.

(i) Ground fire: Which is flameless and subterranean.
(ii) Surface fire: Which consumes the herbs and shrubs.
(iii) Crown fire: Which burns the forest canopy.
Effects of fire
1. Fire has a direct lethal effect on plants.
2. Burning scars are the suitable places for the entry of parasitic fungi and insects.
3. It brings out the alteration of light, rainfall, nutrient cycle, fertility of soil, pH, soil flora and fauna.
4. Some fungi which grow in soil of burnt areas called pyrophilous.
Example: Pyronema confluens

(a) Mutualism: It is an interaction between two species of organisms in which both are benefitted from the obligate association. The following are common examples of mutualism.
(b) Nitrogen fixation : Rhizobium (Bacterium) forms nodules in the roots of leguminous plants and lives symbiotically. The Rhizobium obtains food from leguminous plant and in turn fixes atmospheric nitrogen into nitrate, making it available to host plants.
Other examples:
Water fern (Azolla) and Nitrogen fixing Cyanobacterium (Anabaena) .

Morphological adaptations:
Root system is extensively developed. These roots may be of two types. They are Clinging roots and Aerial roots.
Clinging roots fix the epiphytes firmly on the surface of the supporting objects.
Aerial roots are green coloured roots which may hang downwardly and absorb moisture from the atmosphere with the help of a spongy tissue called velamen.
1. Stem of some epiphytes are succulent and develop pseudo bulb or tuber.
2. Generally the leaves are lesser in number and may be fleshy and leathery.
3. Myrmecophily is a common occurrence in the epiphytic vegetation to prevent the predators
4. The fruits and seeds are very small and usually dispersed by wind, insects and birds.