Plants — U
- Ulex Gorse / Whin
- Ulmus Elm
- Umbellularia californica Balm of Heaven
- Uncaria
- Uncaria gambir Gambier
- Uncaria sinensis
- Uncaria tomentosa Cat's Claw
- Uncarina
- Urceola micrantha
- Urena lobata
- Urtica dioica
- Urtica dioica stinging nettle
- Urtica massaica
- Urtica thunbergiana East Asian nettle
- Uvaria rufa Torres Strait scrambler