I’ve been teaching plant physiology or related courses for a long, long time, and one of the tenets is that woody plants don’t heal. In contrast to animal tissues, when trees and shrubs are wounded the damaged tissues are permanently destroyed. Wounds are compartmentalized and covered with wound wood. Arborists are fond of saying "plants seal, not heal."
That’s all fine and good for woody plant parts, but what about grafts? Since grafting reconnects cambial and phloem tissues, is this "healing?" And what about nonwoody plants, like annual flowers and vegetables?
Oddly, this type of information is sadly lacking in physiology textbooks, but it’s a question that I get routinely from gardeners. And it’s not just an exercise in semantics. People make some poor choices in treating tree wounds, for example, laboring under the false impression that such wounds should be treated with wound paint or bandages so they can "heal."