What tree does tannin come from?

Tannin is a polyphenolic compound found in various plants, but it is most commonly associated with oak trees, particularly species like Quercus robur and Quercus alba. Tannins are present in the bark, leaves, and acorns of these trees. They also occur in other sources, such as chestnut, hemlock, and certain fruits, contributing to their astringent taste. Tannins are widely used in the tanning of leather and in the production of wine.