Noms scientifiques : U
- Ulmus carpinifolia
- Ulmus carpinifolia 'Sarniensis'
- Ulmus carpinifolia 'Wredei'
- Ulmus glabra 'Camperdownii'
- Ulmus laevis
- Ulmus minor
- Ulmus minor 'Sarniensis'
- Ulmus minor 'Wredei'
- Ulmus x hollandica 'Lobel'
- Ulmus x hollandica 'Wredei'
- Ulva lactuca
- Uncarina decaryi
- Uncarina grandidieri
- Uniola latifolia
- Urginea maritima
- Urtica cannabina
- Urtica dioica
- Utricularia cornuta
- Utricularia reniformis
- Utricularia vulgaris
- Uvularia grandiflora