Gall

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Galls or plant galls are abnormal outgrowths^[1] of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites. Galls are often highly organised structures 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 and mite galls.

Contents 1 Causes of plant galls 1.1 Insects 1.2 Fungi 1.3 Bacteria and viruses 1.4 Other Plants 2 Uses 3 Gallery 4 Footnotes 5 See also 6 External links 7 Online references

[edit] Causes of plant galls

[edit] Insects

Insect galls are usually induced by chemicals injected by the larvae or the adults of the insects into the plants, and possibly mechanical damage. After the galls are formed, the larvae develop inside until fully grown, when they leave. In order to form galls, the insects must seize the time when plant cell division occurs quickly: the growing season, usually spring in temperate climates, but which is extended in the tropics.

The meristems, where plant cell division occurs, are the usual sites of galls, though insect galls can be found on other parts of the plant, such as the leaves, stalks, branches, buds, roots, and even flowers and fruits. Gall-inducing insects are usually species-specific and sometimes tissue-specific on the plants they gall.

Gall-inducing insects include gall wasps, gall midges, gall flies, aphids, and psyllids.

[edit] Fungi

A gall-inducing fungus is: Cedar-apple rust. Galls are often seen in Pongamia pinnata leaves and fruits. Leaf galls appear like tiny clubs, however, flower galls are globose.(Suma TS, FRLHT, Bangalore)

[edit] Bacteria and viruses

Crown Gall is an example of a gall-causing bacterium.

[edit] Other Plants

Mistletoe can form galls on its hosts

[edit] Uses

Galls are rich in resins and tannic acid and have been used in the manufacture of permanent inks (such as iron gall ink) and astringent ointments, in dyeing, and in tanning. A high-quality ink has long been made from the Aleppo gall, found on oaks in the Middle East; it is one of a number of galls resembling nuts and called "gallnuts" or "nutgalls'. The larvae in galls is useful for a survival food and fishing bait.

[edit] Gallery

Gall on a Maple leaf	Rose bedeguar gall on a wild rose in summer.	Andricus fecundator	Andricus quercuscalicis
Andricus quercuscalicis	Neuroterus albipes forma laeviusculus	Eucalyptus leaf gall	'Andricus kollari oak gall
Cola-nut galls (Andricus lignicola) on Pedunculate Oak	Gymnosporangium	Oak marble galls, one with a Gall fly exit hole and another with Phoma gallorum fungal attack.	Red-pea gall (Cynips divisa) on Pedunculate oak.
Sectioned gall showing central 'cell' and inquiline chamber; exit-hole and a possibly parasitised stunted gall specimen.	Pineapple gall on Sitka Spruce caused by Adelges abietis.	Developing Pineapple pseudocone galls on Norway Spruce	Goldenrod Gall
An Oak tree with multiple Oak apples.	Oak Apples on an oak tree.	Lime Nail Galls	Gall of peach tree leaves, found at Beijing

[edit] Footnotes

[edit] See also

• Bush coconut
• Mulga apple
• Oak apple
• Oak Marble gall
• Knopper gall
• Oak artichoke gall
• Rose bedeguar gall
• Pineapple gall
• Cola-nut gall

[edit] External links

• Goldenrod Gall Fly
• All Galls Are Divided Into Three Parts (At Least In Goldenrod), Solidago

[edit] Online references

• "Gall". Infoplease encyclopedia. http://www.infoplease.com/ce6/sci/A0820047.html. Retrieved on March 2006. 
• "Common oak gall". University of Kentucky Entomology. http://www.uky.edu/Ag/Entomology/entfacts/trees/ef408.htm. Retrieved on September 11 2006. 

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