Gall

Galls (from Latin galla, 'oak-apple') or cecidia (from Greek kēkidion, anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or warts in animals. They can be caused by various parasites, from viruses, fungi and bacteria, to other plants, insects and mites. Plant galls are often highly organized structures so that the cause of the gall can often be determined without the actual agent being identified. This applies particularly to some insect and mite plant galls. The study of plant galls is known as cecidology.Gall on a Maple leafRose bedeguar gall on a wild rose in summer.Oak artichoke gall (Andricus fecundator)Knopper gall (Andricus quercuscalicis)Knopper gall (Andricus quercuscalicis)Neuroterus albipes forma laeviusculusEucalyptus leaf gallAndricus kollari oak gallAndricus kollari oak gallGymnosporangiumOak marble galls, one with a gall fly exit hole and another with Phoma gallarum fungal attack.Red-pea gall (Cynips divisa) on Pedunculate oak.Cola-nut galls (Andricus lignicola) on Pedunculate OakPineapple gall on Sitka Spruce caused by Adelges abietis.Developing Pineapple pseudocone galls on Norway SpruceGall of Japanagromyza inferna in Centrosema virginianumAn Oak tree with multiple Oak apples.Oak Apples on an oak tree.Lime nail galls (Eriophyes tiliae tiliae)Leaf galls on Rhododendron ferrugineumGall on peach tree leavesEucalyptus cypellocarpa at The Gap Scenic Reserve, AustraliaGall attack on Eucalyptus due to Leptocybe invasa at Acharya N. G. Ranga Agricultural UniversityFruit gall on Actinidia polygama Galls (from Latin galla, 'oak-apple') or cecidia (from Greek kēkidion, anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or warts in animals. They can be caused by various parasites, from viruses, fungi and bacteria, to other plants, insects and mites. Plant galls are often highly organized structures so that the cause of the gall can often be determined without the actual agent being identified. This applies particularly to some insect and mite plant galls. The study of plant galls is known as cecidology. In human pathology, a gall is a raised sore on the skin, usually caused by chafing or rubbing. Insect galls are the highly distinctive plant structures formed by some herbivorous insects as their own microhabitats. They are plant tissue which is controlled by the insect. Galls act as both the habitat and food source for the maker of the gall. The interior of a gall can contain edible nutritious starch and other tissues. Some galls act as 'physiologic sinks', concentrating resources in the gall from the surrounding plant parts. Galls may also provide the insect with physical protection from predators. Insect galls are usually induced by chemicals injected by the larvae 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 take advantage of 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, Agromyzidae aphids (such as Melaphis chinensis, Pemphigus spyrothecae, and Pemphigus betae), scale insects, goldenrod gall fly, psyllids and weevils.