Rhizosphere

Rhizosphere [ Botany ]

Dictionary of botanic terminology - index of names

The soil zone immediately surrounding a growing plant root system, normally the location of large populations of microorganisms

The rhizosphere is a special environment near the root itself, together with that volume of soil which it influences that is, a few millimetres from the root. That zone of the soil is modified as a result of the uptake and deposition of substances by a growing root and by the increased number of microorganisms (eg Rhizobia) that live there, in association with plant roots. The microbial growth is stimulated by root exudates (the rhizosphere effect).
It is also the site where nutrients are transformed for take-up by the plant.

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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