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