Géneros de organismos asociados: Uapaca [2 taxones], Udonga [1 taxon], Ugni [2 taxones], Uleomyces [11 taxones], Ulex [52 taxones], Ullolitsea [1 taxon], Ulmus [1242 taxones], Ulocladium [3 taxones], Ulothrix [1 taxon], Ulva [2 taxones], Umbellularia [1 taxon], Umbilicaria [2 taxones], Umbilicus [5 taxones], Unaspis [6 taxones], Uncaria [13 taxones], Uncinia [33 taxones], Uncinula [8 taxones], Uncinuliella [7 taxones], Ungnadia [3 taxones], Unguiculariopsis [20 taxones], Unguiculella [4 taxones], Uniola [9 taxones], Unona [1 taxon], Unonopsis [1 taxon], Urania [1 taxon], Uraria [14 taxones], Urceola [7 taxones], Urceolella [1 taxon], Urechites [6 taxones], Uredinophila [24 taxones], Uredo [67 taxones], Urelytrum [2 taxones], Urena [40 taxones], Urera [7 taxones], Urginea [22 taxones], Urochloa [153 taxones], Urocystis [2 taxones], Urohendersonia [1 taxon], Uromyces [141 taxones], Urospermum [1 taxon], Urospora [1 taxon], Urostigma [3 taxones], Ursus [4 taxones], Urtica [449 taxones], Urvillea [26 taxones], Usnea [27 taxones], Usteria [1 taxon], Ustilago [6 taxones], Ustulina [11 taxones], Utetheisa [2 taxones], Utharomyces [4 taxones], Utricularia [1 taxon], Uvaria [27 taxones], Uvariodendron [2 taxones]