Dictionary Involute

Involute [ Botany ]	Dictionary of botanic terminology - index of names

With margins rolled inward toward the upper surface.
E.g. petals and leaves in bud.

Involute means curved towards the midvein on the upper surfaces of a petal or leaf, along its longitudinal axis.
When fully involute the margins touch or overlap so only the reverse of the floret is visible.
Sufficient involution will create a tubular petal which may be referred to as Fully Involute or Quilled.

Left: fully involute petals of a dahlia flower.

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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