| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| ULCR | Ulmus crassifolia Nutt. | cedar elm | Ulmaceae
|
| ULDA | Ulmus davidiana Planch. | Japanese elm | Ulmaceae
|
| ULFL | Ulmus floridana Chapman | Ulmus americana | Ulmaceae
|
| ULFU | Ulmus fulva Michx. | Ulmus rubra | Ulmaceae
|
| ULGL | Ulmus glabra Huds. | Wych elm | Ulmaceae
|
| ULMI | Ulmus minor auct. non P. Mill. | Ulmus procera | Ulmaceae
|
| ULNO | Ulmus �notha Wilhelm & G. Ware, hyb. nov. ined. | | Ulmaceae
|
| ULPA | Ulmus parvifolia Jacq. | Chinese elm | Ulmaceae
|
| ULPR | Ulmus procera Salisb. | English elm | Ulmaceae
|
| ULPU | Ulmus pumila L. | Siberian elm | Ulmaceae
|
| ULRA | Ulmus racemosa D. Thomas | Ulmus thomasii | Ulmaceae
|
| ULRU | Ulmus rubra Muhl. | slippery elm | Ulmaceae
|
| ULSE | Ulmus serotina Sarg. | September elm | Ulmaceae
|
| ULTH | Ulmus thomasii Sarg. | rock elm | Ulmaceae
|
| ULMUS | Ulmus L. | elm | Ulmaceae
|
| ULAMR | Ulota americana (P. Beauv.) Limpr. var. rufescens (Britt.) Par. | Ulota hutchinsiae var. rufescens | Orthotrichaceae
|
| ULAM3 | Ulota americana (P. Beauv.) Limpr. | Ulota hutchinsiae var. hutchinsiae | Orthotrichaceae
|
| ULAM2 | Ulota americana Mitt. | Ulota curvifolia | Orthotrichaceae
|
| ULBA | Ulota barclayi Mitt. | Ulota japonica | Orthotrichaceae
|
| ULBR | Ulota bruchii Hornsch. in Brid. | Ulota crispa | Orthotrichaceae
|
| ULCI | Ulota cirrata Grout | Ulota curvifolia | Orthotrichaceae
|
| ULCO | Ulota coarctata (P. Beauv.) Hammar | ulota moss | Orthotrichaceae
|
| ULCRA | Ulota crispa (Hedw.) Brid. var. alaskana (Card. & Th�r.) Grout | Ulota obtusiuscula | Orthotrichaceae
|
| ULCRC | Ulota crispa (Hedw.) Brid. var. crispula (Bruch in Brid.) Hammar | Ulota crispa | Orthotrichaceae
|
| ULCRI | Ulota crispa (Hedw.) Brid. var. intermedia (Schimp.) Card. | Ulota crispa | Orthotrichaceae
|
| ULCR2 | Ulota crispa (Hedw.) Brid. | ulota moss | Orthotrichaceae
|
| ULCR3 | Ulota crispula Bruch in Brid. | Ulota crispa | Orthotrichaceae
|
| ULCU70 | Ulota curvifolia (Wahlenb.) Lilj. | curvedleaf ulota moss | Orthotrichaceae
|
| ULDR | Ulota drummondii (Hook. & Grev. in Grev.) Brid. | Drummond's ulota moss | Orthotrichaceae
|
| ULFU2 | Ulota funstonii Grout | Ulota drummondii | Orthotrichaceae
|
| ULHUH | Ulota hutchinsiae (Sm.) Hammar var. hutchinsiae | Hutchins' ulota moss | Orthotrichaceae
|
| ULHUR | Ulota hutchinsiae (Sm.) Hammar var. rufescens (Britt.) Dix. | Hutchins' ulota moss | Orthotrichaceae
|
| ULHU | Ulota hutchinsiae (Sm.) Hammar | Hutchins' ulota moss | Orthotrichaceae
|
| ULIN | Ulota intermedia Schimp. | Ulota crispa | Orthotrichaceae
|
| ULJA2 | Ulota japonica (Sull. & Lesq.) Mitt. | Japanese ulota moss | Orthotrichaceae
|
| ULLU | Ulota ludwigii (Brid.) Brid. | Ulota coarctata | Orthotrichaceae
|
| ULMA | Ulota maritima C. M�ll. & Kindb. in Mac. & Kindb. | Ulota phyllantha | Orthotrichaceae
|
| ULME | Ulota megalospora Vent. in R�ll | largespore ulota moss | Orthotrichaceae
|
| ULOB | Ulota obtusiuscula C. M�ll. & Kindb. in Mac. & Kindb. | ulota moss | Orthotrichaceae
|
| ULPH | Ulota phyllantha Brid. | ulota moss | Orthotrichaceae
|
| ULRE | Ulota reptans Mitt. | ulota moss | Orthotrichaceae
|
| ULUL | Ulota ulophylla Broth. | Ulota crispa | Orthotrichaceae
|
| ULOTA | Ulota Mohr | ulota moss | Orthotrichaceae
|
| UMCAC | Umbellularia californica (Hook. & Arn.) Nutt. var. californica | California laurel | Lauraceae
|
| UMCAF | Umbellularia californica (Hook. & Arn.) Nutt. var. fresnensis Eastw. | California laurel | Lauraceae
|
| UMCA | Umbellularia californica (Hook. & Arn.) Nutt. | California laurel | Lauraceae
|
| UMBEL | Umbellularia (Nees) Nutt. | California laurel | Lauraceae
|
| UMAM | Umbilicaria americana Poelt & T. Nash | navel lichen | Umbilicariaceae
|
| UMAN60 | Umbilicaria angulata Tuck. | navel lichen | Umbilicariaceae
|
| UMAP | Umbilicaria aprina Nyl. | navel lichen | Umbilicariaceae
|
| UMAR60 | Umbilicaria arctica (Ach.) Nyl. | arctic navel lichen | Umbilicariaceae
|
| UMCA60 | Umbilicaria caroliniana Tuck. | Carolina navel lichen | Umbilicariaceae
|
| UMCI60 | Umbilicaria cinereorufescens (Schaerer) Frey | navel lichen | Umbilicariaceae
|
| UMCO | Umbilicaria coriacea Imshaug | Umbilicaria rigida | Umbilicariaceae
|
| UMCR | Umbilicaria crustulosa (Ach.) Frey | crusty navel lichen | Umbilicariaceae
|
| UMCY60 | Umbilicaria cylindrica (L.) Delise ex Duby | cylindric navel lichen | Umbilicariaceae
|
| UMDE60 | Umbilicaria decussata (Vill.) Zahlbr. | navel lichen | Umbilicariaceae
|
| UMDE61 | Umbilicaria deusta (L.) Baumg. | navel lichen | Umbilicariaceae
|
| UMHA | Umbilicaria havaasii Llano | Havaas' navel lichen | Umbilicariaceae
|
| UMHI60 | Umbilicaria hirsuta (Sw. ex Westr.) Hoffm. | hairy navel lichen | Umbilicariaceae
|
| UMHYH | Umbilicaria hyperborea (Ach.) Hoffm. var. hyperborea | navel lichen | Umbilicariaceae
|
| UMHYR | Umbilicaria hyperborea (Ach.) Hoffm. var. radicicula (J. E. Zetterst.) Hasselrot | navel lichen | Umbilicariaceae
|
| UMHY2 | Umbilicaria hyperborea (Ach.) Hoffm. | navel lichen | Umbilicariaceae
|
| UMKR60 | Umbilicaria krascheninnikovii (Savicz) Zahlbr. | Krascheninnikov's navel lichen | Umbilicariaceae
|
| UMLA | Umbilicaria lambii Imshaug | Lamb's navel lichen | Umbilicariaceae
|
| UMLE | Umbilicaria leiocarpa DC. | navel lichen | Umbilicariaceae
|
| UMLY60 | Umbilicaria lyngei Schol. | Lynge's navel lichen | Umbilicariaceae
|
| UMMA60 | Umbilicaria mammulata (Ach.) Tuck. | navel lichen | Umbilicariaceae
|
| UMMU60 | Umbilicaria muehlenbergii (Ach.) Tuck. | Muehlenberg's navel lichen | Umbilicariaceae
|
| UMNY | Umbilicaria nylanderiana (Zahlbr.) H. Magn. | Nylander's navel lichen | Umbilicariaceae
|
| UMPA | Umbilicaria papulosa (Ach.) Nyl. | Lasallia papulosa | Umbilicariaceae
|
| UMPE | Umbilicaria pensylvanica Hoffm. | Lasallia pensylvanica | Umbilicariaceae
|
| UMPH | Umbilicaria phaea Tuck. | navel lichen | Umbilicariaceae
|
| UMPO60 | Umbilicaria polyphylla (L.) Baumg. | manyleaf navel lichen | Umbilicariaceae
|
| UMPO2 | Umbilicaria polyrrhiza (L.) Fr. | manyroot navel lichen | Umbilicariaceae
|
| UMPR60 | Umbilicaria proboscidea (L.) Schrader | navel lichen | Umbilicariaceae
|
| UMPUP | Umbilicaria pustulata (L.) Hoffm. var. papulosa (Ach.) Tuck. | Lasallia papulosa | Umbilicariaceae
|
| UMPU | Umbilicaria pustulata (L.) Hoffm. | Lasallia pustulata | Umbilicariaceae
|
| UMRI | Umbilicaria rigida (Du Rietz) Frey | rigid navel lichen | Umbilicariaceae
|
| UMSC | Umbilicaria scholanderi (Llano) Krog | Scholander's navel lichen | Umbilicariaceae
|
| UMTO60 | Umbilicaria torrefacta (Lightf.) Schrader | navel lichen | Umbilicariaceae
|
| UMVE60 | Umbilicaria vellea (L.) Ach. | navel lichen | Umbilicariaceae
|
| UMVI60 | Umbilicaria virginis Schaerer | navel lichen | Umbilicariaceae
|
| UMBIL2 | Umbilicaria Hoffm. | navel lichen | Umbilicariaceae
|
| UNAL | Unamia alba (Nutt.) Rydb. | Oligoneuron album | Asteraceae
|
| UNLU | Unamia lutescens (Lindl. ex DC.) Rydb. | Oligoneuron lutescens | Asteraceae
|
| UNGA | Uncaria gambir (Hunter) Roxb. | gambir | Rubiaceae
|
| UNCAR | Uncaria Schreber | uncaria | Rubiaceae
|
| UNBR | Uncinia brevicaulis Thouars | false watermeal | Cyperaceae
|
| UNHA | Uncinia hamata (Sw.) Urban | birdcatching sedge | Cyperaceae
|
| UNUNU2 | Uncinia uncinata (L. f.) K�kenth. var. uliginosa Skottsberg | Uncinia uncinata | Cyperaceae
|
| UNUN | Uncinia uncinata (L. f.) K�kenth. | Hawai'i birdcatching sedge | Cyperaceae
|
| UNCIN | Uncinia Pers. | birdcatching sedge | Cyperaceae
|
| UNSP | Ungnadia speciosa Endl. | Mexican buckeye | Sapindaceae
|
| UNGNA | Ungnadia Endl. | ungnadia | Sapindaceae
|
| UNCA | Unifolium canadense (Desf.) Greene | Maianthemum canadense | Liliaceae
|
| UNLA3 | Uniola latifolia Michx. | Chasmanthium latifolium | Poaceae
|
| UNLA4 | Uniola laxa (L.) B.S.P. | Chasmanthium laxum | Poaceae
|
| UNLO | Uniola longifolia Scribn. | Chasmanthium sessiliflorum | Poaceae
|
| UNNI2 | Uniola nitida Baldw. | Chasmanthium nitidum | Poaceae
|
| UNOR2 | Uniola ornithorhyncha Steud. | Chasmanthium ornithorhynchum | Poaceae
|