Gall

Gall [ Botany - Phytopathology - Phytoparasitology ]

Dictionary of botanic terminology
index of names

Abnormal swelling or outgrowth of plant tissue as a result of attack by a pathogen or other pest or injury.

Galls develops from the proliferation of unorganized cell tissue (or tumour) in plants and can be caused by various living agents from parasitic fungi, bacteria (as in Crown Gall) and viruses, to various insects, nematode and mites, usually found on leaves or stems but may also occur on other plant parts. Galls may develop either by localized cell proliferation or increase in cell size

Often, they are very organised structures that are often more or less spherical (But may come in various shapes from round to spindle-shaped. Their textures can also vary. They can be smooth or sticky, hairy, fluffy, scaly, or bumpy) and because of this, the cause of the gall can often be determined without the actual agent being identified.

This applies particularly to some insect galls in which the swollen part of the plant, derives from an insect larva (baby insect) that is living inside it. The gall is the temporary home for the insect. It is formed when the insect injects or secretes a substance into the plant, causing part of the plant to swell or grow abnormally. Some species of wasps and flies inject their eggs into plant stems or leaves. The plant keeps growing, forming a ball-shaped gall around the egg and provides protection and food for the larva while it develops.. When the larva hatches, it eats its way out. Sometimes galls hurt the plant and sometimes they don't with no harm other than it is unsightly.

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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