Canopy

Canopy [ Botany - Ecology ]

Dictionary of botanic terminology - index of names


	The more or less continuous cover of branches and foliage formed collectively by the crowns of adjacent trees in a forest or woodland, or the upper foliage and branches of an individual tree.

The canopy is the "roof" a woodland or forest, the more or less continuous uppermost layer of vegetation formed by the crown (foliage and branches) of the tallest trees or the upper foliage and branches of an individual tree or shrub. The density of the canopy is a parameter used to differentiate woodland from a forest. A forest form a largely-closed canopy, in other words, the branches and foliage of trees interlock overhead, cover and furnish nearly a continuous shade, while a woodland has a largely-open canopy (the tree crowns cover less than 20-30 % of the ground) with sunlight penetrating between trees.

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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