Radial

Radial [ Biology - Botany ]
Adverb: Radially
Synonyms: Symmetric, Stellate or Starlike
Derived form: Radiating

Dictionary of botanic terminology
index of names

Radiating from or converging to a common centre. Having or characterized by parts so arranged or so radiating. Developing symmetrically about a central point.

Radial spines of
Coryphantha echinoidea

In biology the term radial describe the arrangement of parts of an organism (such as the petals of a flower, the rays of a starfish or the spines of a cactus) in which the parts develop in a circular symmetrical arrangement around a central point: Radial projections; Also applied to a rootstock in which the fronds radiate and the roots are borne on all sides of the organ. ( See: Radial symmetry }

Stellate flowers of
Stapelia flavopurpurea

Stellate (radial) stem of
Astrophytum cohauilense

(From Latin "radius" ray)

To radiate (Verb)

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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