| Scientific name | Quercus robur / Quercus alba |
| Appearance | Bark in irregular pieces, rough and fibrous, sometimes striated |
| Smell | Woody, dry, slightly astringent |
| Color | Gray-brown to dark brown, with beige highlights inside |
| Used parts | Dried bark (external part of the trunk or branches) |
| Origins | Europe, North America, Western Asia (depending on the species) |
| Toxicity level | Low (external use or well-tolerated herbal tea; to be avoided for prolonged use or high internal doses) |
