Most of galls are foes but some are friends

This review article is about how plants form galls in response to the presence of foreign organisms. Some of these organisms are beneficial to the plant, while most are harmful. The galls serve as a way for the plant to accommodate the foreign species and potentially protect itself.

Galls are abnormal growths or structures that form on plants in response to the presence of foreign organisms, such as insects, mites, bacteria, or fungi. They are formed as a result of changes in the plant’s growth patterns, triggered by chemical signals produced by the invading organism.

Galls can serve a variety of purposes for both the plant and the invading organism. In some cases, the gall provides a protective shelter for the invader, allowing it to feed, grow, and reproduce without being damaged by the plant’s defense mechanisms. For the plant, galls can serve as a way to limit the damage caused by the invader and prevent it from spreading to other parts of the plant. Most galls are formed by harmful invaders, such as insect pests or pathogens, that cause significant damage to the plant. These galls can weaken the plant, reduce its ability to photosynthesize, and make it more susceptible to other problems.

However, not all galls are created equal. Some galls are formed by beneficial organisms that live in symbiotic relationships with the plant, providing essential nutrients or other benefits in exchange for a safe home. For example, some species of wasps lay their eggs in galls on oak trees, and the larvae feed on the plant tissue. This process causes little damage to the plant, and in some cases, the wasp larvae produce hormones that stimulate the growth of the gall, benefiting both the wasp and the tree.