Tannin Defense Systems

When insects attack, many trees ramp up tannin production sharply within a couple of days. Tannins bind to proteins in the insect's gut, making leaves indigestible. Trees that were attacked before keep their tannin baseline elevated — a chemical memory that holds defenses primed.

The same compound that makes leaves unpalatable also kills pathogens at wound sites. Tannins are dual-purpose chemistry: an anti-herbivore weapon and an antimicrobial wound sealant.