Nitrogen

Nitrogen [ Physiology - Chemistry ]
Abbreviation: N

Dictionary of botanic terminology - index of names

Nitrogen deficiency [ Horticulture - Phytopathology ]


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

Nitrogen is required by plants in higher concentrations than any of the other elements, except potassium in certain instances. Plants grown without nitrogen grow very slowly. Plants are stunted and show a general yellowing of the foliage. The symptoms of nitrogen deficiency will first occur in the older leaves. The leaves turn from a pale green colour to a yellow and eventually leaf drop occurs. The younger leaves remain green for longer periods of time but eventually the whole plant exhibits a pale green to yellow colour.

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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