Parasite

Parasite [ Biology - Horticulture ]
Adjective: Parasitic
Derived form: Parasitism, Parasitology

Dictionary of botanic terminology
index of names

An organism that lives on or in a host organism of a different species and that gets its food from or at the expense of its host, and which is typically detrimental to the host.

A parasite is an organism that lives intimately associated in or on the living tissue of a host organism. A parasite obtains nourishment and shelter from the host without benefiting or killing it usually does not eat a large proportion of its host tissue. A parasite does not help its host in any way.
A complete parasite gets all of its nutrients from the host organism, whilst a semi-parasite gets only some of its food from the host.
The biological interaction between the host and the parasite is called parasitism. Parasitism is almost a form of predation, it is a type of symbiosis, by one definition, although another definition of symbiosis excludes parasitism, since it requires that the host benefit from the interaction as well as the parasite. (Of course animals and plants may be parasitized or parasites too.)

Some parasitic insects are considered beneficial because parasitize pest species.

Among plant parasites: Mealy bug, aphids, nematodes, etc.

See also: Ectoparasite, Endoparasites, Parasitic plants, Parasitic diseases

Compare with: Saprophyte.

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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