Glaucous

Glaucous [ Botany - Surface feature ]
Synonym: pruinose

Dictionary of botanic terminology - index of names

The word glaucous refers to the greyish/ bluish colour of leaves, stems or fruits produced by the presence a fine bloom or fine white powder of wax on the epidermis surface.

The glaucous stem of Acanthocalycium glaucum

From the Greek word “Glaucos (γλαυκοζ )” meaning "bright, gleaming; greyish, bluish-green”

Many succulents, in deserts have grey or bluish photosynthetic organs covered by a loose surface wax, called Epicuticular wax or pruina), which is very reflective. When a leaf appears bluish or grey (glaucous), rather than bright green, epicuticular wax is generally the cause. This can be confirmed by rubbing off the waxy coating from the surface to reveal the green leaf colour beneath.
(Examples: Acanthocalycium glaucum, Myrtillocactus geometrizans, Echeveria lauii spp..)

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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