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Gall
* Many galls provide the food and brooding structure for various species of harmless insects.
* More galls occur on oak than on any other host plant.
* Most galls are difficult to control since insect life cycles vary so much
  - on the leaves but some are on flowers, petioles, green stems, and even roots
  - occur on early spring foliage that develops near the trunk and on larger branches
  - taste similar to the host plant
* Some gall protects larvae.
* Some galls are dark red or purple and contain anthocyanins while others are green
  - contain a very high content of bitter tannins, and are probably unpalatable to predators
  - form where insects or mites feed or lay eggs
* act as both the habitat, and food sources for the maker of the gall.
* affecting twigs such as the gouty oak gall and horned oak gall can be more serious.
* also form at trunk or limb wounds
  - on pegs and pods of peanut
  - provide some protection from natural enemies and insecticide sprays
* always arise near leaf edges, and the tops of galls are often toward leaf edges
  - surround the gall-inducing organism offering protection and a food source
* appear on all underground parts except the roots.
* are a common sight on many plants, including weeds, shrubs and trees
  - abnormal plant growth or swellings comprised of plant tissue
  - about the size of large hickory nut, cone-shaped and found one to a twig at the very tip
  - also largely imported from Persia and to a lesser extent from Greece
  - bladderlike, red, and found on the top side of leaves
  - caused mostly by gall mites
  - deformities found on the leaves, stems and flowers of trees, shrubs and other plants
  - excrescences produced in plants by the presence of the larvae of different insects
* are growths on leaves, stems and twigs of many different plants
  - plants that are induced by parasitic organisms
  - irregular growths or swellings
  - normally dark brown to black and have a roughened appearance
  - produced by insects of various orders, but the greater number by species of Cynips
  - quite common on plants like hackberry and oaks
  - rich in proteins and carbohydrates
  - soft and spongy
  - unusual growths that form on the upper or lower surface of leaves
  - visible to the unaided eye, particularly after mid-season
* can be small, or they can develop into swellings an inch or more in diameter
  - spherical or contorted into a variety of shapes
  - the result of attack by certain insects, bacteria, fungi, or nematodes
  - up to several inches in diameter
  - form on roots or stems
  - grow on the stem, root or crown of the plant
  - hang on the tree for a few years after wasps leave, harboring a host of other insects
* causes an overgrowth of cell walls.
* come in a variety of sizes, shapes and colors
  - wide variety of shapes and colors and are caused by a wide variety of insects
* commonly develop where plants have been suckered or injured during cultivation or pruning.
* consists of a mass of brown, moss-like filaments covering a hard kernel.
* dry up and fall resulting in reduced foliage and an unsightly canopy.
* form as the pathogen invades host tissue and induces hypertrophy and hyperplasia
  - favorable places for fungi to attack
  - in response to a chemical that the insect injects into the plant tissue
* form on roots and stems, especially at the root collar, or root crown
  - stems and portions of the stem distal to the gall eventually die
* form on the leaves and later on the stems
  - roots, and the crown and leaves become thickened and distorted
  - the following spring
* forming herbivores induce sinks and act as phloem parasites within their host plants.
* frequently appear on oaks.
* have no marked odour, but an intensely astringent taste, and slightly sweet after-taste.
* is hatred
  - office holders
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* occasionally occur on branches or on roots.
* occur in many different shapes.
* occur on almost any plant tissues
  - leaves, tendrils, and blossom buds and can occasionally cause considerable injury
* often are unusual in form, conspicuous, and frequently cause considerable concern.
* points out that seafood has many nutritional advantages over other protein sources.
* produced by aphid-like immature stages appear as folded leaves on new, terminal growth.
* protect the adelgid from most insecticide sprays.
* provide protection and nourishment for the insect larvae as they develop.
* reduce tree vigor by retarding the flow of water and nutrients in the vascular tissue.
* result from an intricate interaction between two living organisms.
* slowly enlarge each year.
* start forming.
* suppress new growth and reduce seed production.
* tend to be more abundant on the lower branches.
* turn brown by late summer and in the fall become dry and corky.
* typically develop in spring at about the time that leaves are expanding.
* usually appear near the soil line or graft union
  - form on a small proportion of the leaves and tree health is unaffected
* vary greatly in shape but are more or less tuber-like
  - in appearance depending on the plant infected and the nematode species