Polyphenol classification tree, for reference:

Polyphenols
├── Flavonoids
│   ├── Flavonols (e.g., quercetin, kaempferol)
│   ├── Flavones (e.g., luteolin, apigenin)
│   ├── Flavanones (e.g., naringenin, hesperetin)
│   ├── Flavanols / Flavan-3-ols (e.g., catechin, epicatechin)
│   ├── Anthocyanidins / Anthocyanins (e.g., cyanidin, delphinidin)
│   ├── Isoflavones (e.g., daidzein, genistein)
│   ├── Flavanonols (e.g., taxifolin)
│   └── Chalcones (open-chain flavonoids)
├── Phenolic Acids
│   ├── Hydroxybenzoic acids (e.g., gallic acid, protocatechuic acid)
│   └── Hydroxycinnamic acids (e.g., caffeic acid, ferulic acid, chlorogenic acid)
├── Stilbenes (e.g., resveratrol)
└── Lignans (e.g., secoisolariciresinol, matairesinol)