| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| URDIC | Urtica dioica L. var. californica (Greene) C.L. Hitchc. | Urtica dioica ssp. gracilis | Urticaceae
|
| URDIG2 | Urtica dioica L. var. gracilis (Ait.) C.L. Hitchc. | Urtica dioica ssp. gracilis | Urticaceae
|
| URDIH2 | Urtica dioica L. var. holosericea (Nutt.) C.L. Hitchc. | Urtica dioica ssp. holosericea | Urticaceae
|
| URDIL | Urtica dioica L. var. lyallii (S. Wats.) C.L. Hitchc. | Urtica dioica ssp. gracilis | Urticaceae
|
| URDIO | Urtica dioica L. var. occidentalis S. Wats. | Urtica dioica ssp. holosericea | Urticaceae
|
| URDIP2 | Urtica dioica L. var. procera (Muhl. ex Willd.) Weddell | Urtica dioica ssp. gracilis | Urticaceae
|
| URDI | Urtica dioica L. | stinging nettle | Urticaceae
|
| URGR | Urtica gracilenta Greene | mountain nettle | Urticaceae
|
| URGRH | Urtica gracilis Ait. ssp. holosericea (Nutt.) W.A. Weber | Urtica dioica ssp. holosericea | Urticaceae
|
| URGRG | Urtica gracilis Ait. var. greenei (Jepson) Jepson | Urtica dioica ssp. holosericea | Urticaceae
|
| URGRH2 | Urtica gracilis Ait. var. holosericea (Nutt.) Jepson | Urtica dioica ssp. holosericea | Urticaceae
|
| URGRL | Urtica gracilis Ait. var. latifolia Farw. | Urtica dioica ssp. dioica | Urticaceae
|
| URGR3 | Urtica gracilis Ait. | Urtica dioica ssp. gracilis | Urticaceae
|
| URGR2 | Urtica grandis Hook. & Arn. | Boehmeria grandis | Urticaceae
|
| URHE2 | Urtica herniarioides Sw. | Pilea herniarioides | Urticaceae
|
| URHO2 | Urtica holosericea Nutt. | Urtica dioica ssp. holosericea | Urticaceae
|
| URIN | Urtica interrupta L. | Laportea interrupta | Urticaceae
|
| URLYC | Urtica lyallii S. Wats. var. californica (Greene) Jepson | Urtica dioica ssp. gracilis | Urticaceae
|
| URLY2 | Urtica lyallii S. Wats. | Urtica dioica ssp. gracilis | Urticaceae
|
| URMA | Urtica major H.P. Fuchs | Urtica dioica ssp. gracilis | Urticaceae
|
| URNI | Urtica nivea L. | Boehmeria nivea | Urticaceae
|
| URNU2 | Urtica nummulariifolia Sw. | Pilea nummulariifolia | Urticaceae
|
| URPA2 | Urtica parietaria L. | Pilea parietaria | Urticaceae
|
| URPR | Urtica procera Muhl. ex Willd. | Urtica dioica ssp. gracilis | Urticaceae
|
| URPU2 | Urtica pumila L. | Pilea pumila var. pumila | Urticaceae
|
| URSE3 | Urtica serra auct. non Blume | Urtica dioica ssp. gracilis | Urticaceae
|
| URST2 | Urtica strigosissima Rydb. | Urtica dioica ssp. gracilis | Urticaceae
|
| URTR2 | Urtica trachycarpa Weddell | Urtica dioica ssp. holosericea | Urticaceae
|
| URTR3 | Urtica trianthemoides Sw. | Pilea trianthemoides | Urticaceae
|
| URUR | Urtica urens L. | dwarf nettle | Urticaceae
|
| URVI | Urtica viridis Rydb. | Urtica dioica ssp. gracilis | Urticaceae
|
| URTIC | Urtica L. | nettle | Urticaceae
|
| URDI3 | Urticastrum divaricatum (L.) Kuntze | Laportea canadensis | Urticaceae
|
| URUL | Urvillea ulmacea Kunth | apaac | Sapindaceae
|
| URVIL | Urvillea Kunth | urvillea | Sapindaceae
|
| USAC | Usnea aculeata Mot. | beard lichen | Parmeliaceae
|
| USAF | Usnea affinis Mot. | beard lichen | Parmeliaceae
|
| USAL | Usnea alpina Mot. | alpine beard lichen | Parmeliaceae
|
| USAM | Usnea amabilis Mot. | beard lichen | Parmeliaceae
|
| USAM2 | Usnea amblyoclada (Mull. Arg.) Zahlbr. | beard lichen | Parmeliaceae
|
| USAM3 | Usnea ammannii P. Clerc & Herrera-Campos | beard lichen | Parmeliaceae
|
| USAN | Usnea angulata Ach. | beard lichen | Parmeliaceae
|
| USAN2 | Usnea antillarum (Vainio) Zahlbr. | Usnea baileyi | Parmeliaceae
|
| USAR | Usnea arizonica Mot. | Arizona beard lichen | Parmeliaceae
|
| USAU | Usnea australis Fr. | beard lichen | Parmeliaceae
|
| USBA60 | Usnea baileyi (Stirton) Zahlbr. | Bailey's beard lichen | Parmeliaceae
|
| USBAX | Usnea barbata (L.) F. H. Wigg. var. xanthopoga Mull. Arg. | Usnea xanthopoga | Parmeliaceae
|
| USBE | Usnea betulina Mot. | Usnea glabrescens | Parmeliaceae
|
| USCA2 | Usnea californica Herre | California beard lichen | Parmeliaceae
|
| USCA3 | Usnea capillaris Mot. | beard lichen | Parmeliaceae
|
| USCA4 | Usnea catenulata Mot. | beard lichen | Parmeliaceae
|
| USCA5 | Usnea caucasica Vainio | Usnea filipendula | Parmeliaceae
|
| USCA60 | Usnea cavernosa Tuck. | cavern beard lichen | Parmeliaceae
|
| USCE | Usnea ceratina Ach. | beard lichen | Parmeliaceae
|
| USCI | Usnea ciliifera Mot. | beard lichen | Parmeliaceae
|
| USCI2 | Usnea cirrosa Mot. | beard lichen | Parmeliaceae
|
| USCO4 | Usnea comosa auct. | Usnea subfloridana | Parmeliaceae
|
| USCO5 | Usnea compacta (Rasanen) Mot. | Usnea glabrescens | Parmeliaceae
|
| USCO | Usnea condensata Mot. | condensed beard lichen | Parmeliaceae
|
| USCO2 | Usnea confusa Asah. | confused beard lichen | Parmeliaceae
|
| USCO3 | Usnea cornuta Korber | beard lichen | Parmeliaceae
|
| USDA2 | Usnea dasaea Stirton | beard lichen | Parmeliaceae
|
| USDA | Usnea dasypoga auct. | Usnea filipendula | Parmeliaceae
|
| USDE | Usnea deformis Mot. | deformed beard lichen | Parmeliaceae
|
| USDI | Usnea dimorpha (Mull. Arg.) Mot. | beard lichen | Parmeliaceae
|
| USDI2 | Usnea diplotypus Vainio | beard lichen | Parmeliaceae
|
| USDI3 | Usnea distincta Mot. | Usnea glabrescens | Parmeliaceae
|
| USDU | Usnea duriuscula Mot. | beard lichen | Parmeliaceae
|
| USEN | Usnea endochrysea Stirton | beard lichen | Parmeliaceae
|
| USER2 | Usnea erinacea Vainio | beard lichen | Parmeliaceae
|
| USES | Usnea esthonica Rasanen | Usnea filipendula | Parmeliaceae
|
| USEV | Usnea evansii Mot. | Evans' beard lichen | Parmeliaceae
|
| USFI60 | Usnea fibrillosa Mot. | beard lichen | Parmeliaceae
|
| USFI61 | Usnea filipendula Stirton | beard lichen | Parmeliaceae
|
| USFI2 | Usnea finkii Zahlbr. | Fink's beard lichen | Parmeliaceae
|
| USFL2 | Usnea flagellata Mot. | Usnea filipendula | Parmeliaceae
|
| USFL | Usnea florida (L.) F. H. Wigg. | Florida beard lichen | Parmeliaceae
|
| USFRM | Usnea fragilescens Hav. ex Lynge var. mollis (Vainio) Clerc | soft beard lichen | Parmeliaceae
|
| USFR | Usnea fragilescens Hav. ex Lynge | fragile beard lichen | Parmeliaceae
|
| USFR2 | Usnea freyi Mot. | Frey's beard lichen | Parmeliaceae
|
| USFU | Usnea fulvoreagens (Rasanen) Rasanen | beard lichen | Parmeliaceae
|
| USFU2 | Usnea furfurosula (Zahlbr.) Mot. | beard lichen | Parmeliaceae
|
| USGL60 | Usnea glabrata (Ach.) Vainio | beard lichen | Parmeliaceae
|
| USGL61 | Usnea glabrescens (Nyl. ex Vainio) Vainio | beard lichen | Parmeliaceae
|
| USGR | Usnea graciosa Mot. | beard lichen | Parmeliaceae
|
| USHA | Usnea halei P. Clerc | beard lichen | Parmeliaceae
|
| USHE | Usnea hesperina Mot. | beard lichen | Parmeliaceae
|
| USHI60 | Usnea hirta (L.) F. H. Wigg. | beard lichen | Parmeliaceae
|
| USIM | Usnea implicata (Stirton) Zahlbr. | Usnea baileyi | Parmeliaceae
|
| USIN2 | Usnea inflata Delise ex Duby | Usnea cornuta | Parmeliaceae
|
| USKU | Usnea kujalae Rasanen | Usnea glabrata | Parmeliaceae
|
| USLA60 | Usnea lapponica Vainio | Lapland beard lichen | Parmeliaceae
|
| USLA2 | Usnea laracina Vainio ex Rasanen | Usnea lapponica | Parmeliaceae
|
| USLE60 | Usnea leucosticta Vainio | beard lichen | Parmeliaceae
|
| USLOC | Usnea longissima Ach. var. corticata R. Howe | beard lichen | Parmeliaceae
|
| USLO50 | Usnea longissima Ach. | beard lichen | Parmeliaceae
|
| USMA | Usnea madierensis Mot. | beard lichen | Parmeliaceae
|
| USME | Usnea merrillii Mot. | Merrill's beard lichen | Parmeliaceae
|
| USMI | Usnea michauxii I. Tav. | Michaux's beard lichen | Parmeliaceae
|
| USMI2 | Usnea mirabilis Mot. | beard lichen | Parmeliaceae
|
| USMO2 | Usnea mollis Stirton | Usnea fragilescens var. mollis | Parmeliaceae
|