Pruina

Pruina or Epicuticular wax [ Botany ]
(Syn: Hoarfrost, Bloom)
Adjective: Pruinose

Dictionary of botanic terminology
index of names

A waxy powdery substance which covers the surfaces of certain fruits (like the bloom of plum and grape) and of different plant organs (leaf, stems etc.)

A nice rosette of pruinose leaves of Echeveria lauii

From Latin pruina “hoarfrost.”

The pruina or epicuticular wax is a fine more or less crystalline, farinaceous dust, easily removable, which one can usually wipe with the finger. Pruina has a protective functions it make skin impermeable to water, reflect intense sun radiation an protect against bacteria and insects attacks.

Pruinose [ Botany - Surface feature ]
(Synonyms: Glaucous )


	A surface feature that can be found on different organs of a plant. Having a blue-grey appearance, as if frosted; with the brightness of a plum-like bloom, due to a bloom or a powdery coating of wax (Pruina).

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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