Podarium

Podarium [ Botany ]
Synonym: Podaria

Dictionary of botanic terminology - index of names


	A podarium is a modified leaf base of a cactus or other succulents, thus the leaf base functions as the photosynthetic part, a combination of leaf and stem.

The podarium generally take the form of a tubercle (for example the tubercles of Mammillaria). The podaria of some species have become fused into vertical ribs that cover the entire surface of the plant. The Echinocactus grusonii provides a good example of this type of ribbing.

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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