Niche

Niche [ Ecology ]	Dictionary of botanic terminology - index of names
Synonym: Ecological niche, Environmental niche.

The unique environment or set of ecological conditions in which a specific plant or animal species occurs, and the function the organism serves within that ecosystem.

In a general meaning, a niche is a special place within the scheme of things. It sometimes denotes the function or position of a thing within a structure.
In ecology a niche is the role of an organism within its environment and community (affecting its survival as a species), the ecological opportunities it exploits and its adaptive response to that environment. Includes nutrition, where it lives, when it’s active and its interaction with other living things.
Practically a niche is the physical and functional "address" of an organism within an ecosystem (the special area with special conditions that supplies a species with factors necessary for its survival) or the life style of an organism, where a living thing is found and what it does there.

Each organism has a specific role (or job) referred to as its niche, and two species are not expected to share the same exact niche for long.

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Holdfast roots [ Botany ]
Dictionary of botanic terminology - index of names

Some species of climbing plants develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place.

Climbing plants, like the poison ivy (Toxicodendron radicans), Boston ivy (Parthenocissus tricuspidata), and trumpet creeper (Campsis radicans), develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place. Usually the Holdfast roots die at the end of the first season, but in some species they are perennial. In the tropics some of the large climbing plants have hold-fast roots by which they attach themselves, and long, cord-like roots that extend downward through the air and may lengthen and branch for several years until they strike the soil and become absorbent roots.

Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House, 1994