Association

Association [ Ecology ]
(Plant association or Floristic association)

Dictionary of botanic terminology
index of names


	A stable and distinctive grouping of plant species occurring in a theoretical terminal or climax community, with ecologically similar requirements that live together in a certain geographical region and constitute a type of biotic community with one or more dominant species from which the group derives a definite character.

Plant association (also called floristic association) are a kind of plant community in which the dominant stratum has a qualitatively uniform floristic composition and which exhibits a uniform structure as a whole, though possibly different floristic composition in the lower stratum which is in equilibrium through competition and other relationships, capable of self-perpetuation and whose species composition has a certain stability.

A plant association can be thought of as a terminal or climax community, identified by indicator species.

They are assemblages of organisms with ecologically similar requirements unique in their composition; occur in particular locations under particular environmental influences on the site such as soils, temperature, elevation, solar radiation, slope, aspect, and precipitation. The association is therefore a classification system for grouping plant species that reoccur on the landscape within particular environmental tolerances. The vegetation is classified on the basis of species presence or absence, the stratification of plant forms, and the spatial distribution of individuals.

The association is named after the dominant species.

Plant associations are used as indicators of environmental conditions such as temperature, moisture, light, etc.

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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