Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
Gall
Introduction References & Edit History
Images
Galls of cynipid wasp Antron douglasii on oak leaves. black knot Leaf galls
Quick Facts
Britannica AI Icon
Adding us as a Preferred Source tells Google you trust our content, so our articles show up more often in your Google Search, Discover feed, and AI Overviews.
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Feedback
Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).
Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

External Websites
Britannica Websites
Articles from Britannica Encyclopedias for elementary and high school students.
Galls of cynipid wasp Antron douglasii on oak leaves.
Galls of cynipid wasp Antron douglasii on oak leaves.

Gall

botany
Written and fact-checked by
Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
Britannica Editors
Last updated
•History

Gall, an abnormal, localized outgrowth or swelling of plant tissue caused by infection from bacteria, fungi, viruses, and nematodes or irritation by insects and mites. See black knot; cedar-apple rust; clubroot; crown gall.