Schizochroism

Schizochromism [ Botany - Biology ] (Schizochroism)	Dictionary of botanic terminology - index of names

A genetic aberration of an organism where there is a total absence of one specific pigment type but every other pigments are present at normal levels.

The term schizochromism (schizochroism) indicate a mutations in which one pigment type is absent but not others. This aberration is common in many cactus cultivar (e.g Gymnocalycium cv. HIBOTAN ) The plant have a colourful yellow or red appearance caused by the total absence of the chlorophyll (green pigment). Here, though, the specific pigment is missing: every other pigment (e.g.. carotenoids and betalains ) are present at normal levels, the dominant green colouration is lost, but will still more than likely have normal other pigments that give the yellow or red overall appearance of stems.

Left: A schizochromic cultivar of Echinofossulocactus

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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