Phosphorus

Phosphorus [ Physiology - Chemistry ]
Abbreviation: P

Dictionary of botanic terminology - index of names

Phosphorus deficiency [ Horticulture - Phytopathology ]


	Absence or insufficiency of phosphorus needed for normal growth and development.

Deficiency symptoms of this element, like nitrogen, are always found in the older plant leaves first. The first symptom is a loss of sheen or shine of the older leaves (some report this as a darker green colour). Next the area along the main veins of the underside of these leaves tends to exhibit red, yellow and bluish pigments. This colouration eventually spreads to other portions of the leaves. The young leaves generally remain green but are reduced in size. Phosphorus-deficient plants are stunted. Maturity of the plant is often delayed. Root development is poor.

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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