| Vorschaubild | Art, Unterart oder Varietät | Familie |  | Fotos von | 
| Preview pict. | Species, Subspecies, or Variety | Family |  | Photos from | 
|  |  Ulex \ Stechginster / Gorse (2 Taxa) |  | Fabaceae \ Schmetterlingsblütler / Legumes |  |  | 
|  |  Ulmus \ Ulme / Elm (3 Taxa + 2 Syn.) |  | Ulmaceae \ Ulmengewächse / Elm Fam. |  |  | 
|  | Ulva lactuca \ Meer-Salat, Meer-Lattich / Sea Lettuce |  | Ulvales \ Grün-Algen / Green Algae |  | NL | 
|  |  Ulvales \ Grün-Alge / Green Algae (7 Taxa) |  | Ulvales \ Grün-Algen / Green Algae |  |  | 
|  |  Umbilicaria \ Nabelflechte / Rock Tripe (2 Taxa) |  | Lecanorales \ Flechten / Lichens |  |  | 
|  |  Umbilicus \ Nabelkraut, Venusnabel / Navelwort (4 Taxa) |  | Crassulaceae \ Dickblattgew. / Stonecrop Fam. |  |  | 
|  | Unknown_bush spec1 \ Unbekannter Strauch / Unknown Bush ? |  | {???} \ {Unbekannte_Familie} / {Unknown_Family} |  | D | 
|  |  Unknown_plant \ Pflanze / Plant (5 Taxa) |  | {???} \ {Unbekannte_Familie} / {Unknown_Family} |  |  | 
|  |  Urginea \ Meerzwiebel / Sea Squill (3 Syn.) |  | Liliaceae \ Liliengewächse / Lily Fam. |  |  | 
|  |  Urospermum \ Schwefelköpfchen / Sheep's Beard, Goldenfleece (2 Taxa) |  | Asteraceae \ Korbblütler / Composite Fam. |  |  | 
|  |  Urtica \ Brenn-Nessel / Nettle (7 Taxa + 2 Syn.) |  | Urticaceae \ Brennnesselgew. / Nettle Fam. |  |  | 
|  |  Utricularia \ Wasserschlauch / Bladderwort (7 Taxa + 2 Syn.) |  | Lentibulariaceae \ Fettkrautgew. / Bladderwort Fam. |  |  | 
|  | udensis, Salix \ Japanische Drachen-Weide, Amur-Weide / Japanese Fantail Willow |  | Salicaceae \ Weidengewächse / Willow Fam. |  | D | 
|  | udicola, Cardamine \ Moor-Schaumkraut / Marsh Bitter-Cress |  | Brassicaceae \ Kreuzblütler / Crucifers |  | A | 
|  | udum agg., Taraxacum \ Flutrasen-Löwenzahn / Marsh Dandelion |  | Asteraceae \ Korbblütler / Composite Fam. |  | D | 
|  |  uliginosa (1 Taxon + 2 Syn.) |  |  |  |  | 
|  |  uliginosum (4 Taxa + 1 Syn.) |  |  |  |  | 
|  |  uliginosus (1 Taxon + 1 Syn.) |  |  |  |  | 
|  | ulmaria, Filipendula \ Echtes Mädesüß / Meadowsweet |  | Rosaceae \ Rosengewächse / Rose Fam. |  | A 
D | 
|  | ulmifolius subsp. sanctus, Rubus −−> Rubus sanctus |  | Rosaceae \ Rosengewächse / Rose Fam. |  | GR 
I | 
|  | ulmifolius, Rubus \ Mittelmeer-Brombeere, Sand-Brombeere / Elmleaf Bramble |  | Rosaceae \ Rosengewächse / Rose Fam. |  | E | 
|  |  umbellata (3 Taxa) |  |  |  |  | 
|  | umbellatum agg., Ornithogalum \ Dolden-Milchstern / White Star of Bethlehem |  | Liliaceae \ Liliengewächse / Lily Fam. |  | Chi 
F 
Rho 
Sam | 
|  | umbellatum s.str., Ornithogalum −−> Ornithogalum angustifolium |  | Liliaceae \ Liliengewächse / Lily Fam. |  | D 
F 
Rho | 
|  | umbellatum subsp. campestre, Ornithogalum −−> Ornithogalum angustifolium |  | Liliaceae \ Liliengewächse / Lily Fam. |  | D 
F 
Rho | 
|  |  umbellatum (3 Taxa) |  |  |  |  | 
|  | umbellatus, Butomus \ Doldige Schwanenblume / Flowering Rush |  | Butomaceae \ Schwanenblumengew. / Flowering Rush Fam.
 |  | D 
S | 
|  | umbelliformis, Artemisia \ Edel-Raute / Yellow Genipi |  | Asteraceae \ Korbblütler / Composite Fam. |  | A | 
|  | umbellulata, Aegilops \ Doldiger Walch / Umbel Goatgrass |  | Poaceae \ Süßgräser / Grass Fam. |  | Sam | 
|  | umbellulatum, Triticum −−> Aegilops umbellulata |  | Poaceae \ Süßgräser / Grass Fam. |  | Sam | 
|  | umbrata, Myosotis arvensis subsp. \ Schatten-Vergissmeinnicht / Common Forget-me-not |  | Boraginaceae \ Borretschgew. / Borrage Fam. |  | A 
D | 
|  | umbrosa subsp. neesii, Scrophularia \ Geflügelte Braunwurz / Green Figwort |  | Scrophulariaceae \ Braunwurzgew. / Figwort Fam. |  | D | 
|  |  umbrosa (3 Taxa) |  |  |  |  | 
|  | umbrosum, Hieracium \ Schattenliebendes Habichtskraut / Shade Hawkweed |  | Asteraceae \ Korbblütler / Composite Fam. |  | D | 
|  |  umbrosus (1 Taxon + 1 Syn.) |  |  |  |  | 
|  | uncialis, Cladonia \ Zahnförmige Cladonie, Igel-Cladonie / Cup Lichen |  | Lecanorales \ Flechten / Lichens |  | S | 
|  |  uncinata (2 Taxa + 2 Syn.) |  |  |  |  | 
|  | undata, Drimia \ Feinwellige Meerzwiebel / Undulate Sea Squill |  | Liliaceae \ Liliengewächse / Lily Fam. |  | Mal | 
|  |  undulata (1 Taxon + 4 Syn.) |  |  |  |  | 
|  | undulatifolia, Tulipa \ Gewelltblättrige Tulpe / Tulip |  | Liliaceae \ Liliengewächse / Lily Fam. |  | Chi 
Les 
Sam | 
|  | undulatum agg., Plagiothecium \ Gewelltes Schiefkapselmoos / Undulate Plagiothecium Moss |  | Musci \ Laubmoose / Mosses |  | D 
S | 
|  |  undulatum (3 Taxa) |  |  |  |  | 
|  | unedo, Arbutus \ Westlicher Erdbeerbaum / Strawberry Tree |  | Ericaceae \ Heidekrautgew. / Heather Fam. |  | Cor 
D 
GR 
HR 
I 
Rho | 
|  | ungeri, Silene \ Ungers Leimkraut / Unger's Campion |  | Caryophyllaceae \ Nelkengew. / Campion Fam. |  | GR 
Kef | 
|  | unguicularis subsp. carica, Iris \ Winter-Iris / Winter-Blooming Iris |  | Iridaceae \ Irisgewächse / Iris Fam. |  | Kef 
Rho | 
|  | unguicularis subsp. cretensis, Iris \ Kretische Schwertlilie / Winter-Blooming Iris |  | Iridaceae \ Irisgewächse / Iris Fam. |  | Kre | 
|  | unguicularis, Iris \ Winter-Iris / Winter-Blooming Iris |  | Iridaceae \ Irisgewächse / Iris Fam. |  | GR | 
|  | unguiculata, Malva \ Zaunrübenblättrige Strauchpappel / Bryony-Leaved Tree-Mallow |  | Malvaceae \ Malvengewächse / Mallow Fam. |  | GR | 
|  | uniflora subsp. glareosa, Silene −−> Silene vulgaris subsp. glareosa |  | Caryophyllaceae \ Nelkengew. / Campion Fam. |  | A | 
|  | uniflora subsp. prostrata, Silene −−> Silene vulgaris subsp. prostrata |  | Caryophyllaceae \ Nelkengew. / Campion Fam. |  | E 
F | 
|  |  uniflora (6 Taxa + 2 Syn.) |  |  |  |  | 
|  |  uniflorum (3 Taxa + 2 Syn.) |  |  |  |  | 
|  | uniflorus subsp. aragonensis, Erigeron −−> Erigeron aragonensis |  | Asteraceae \ Korbblütler / Composite Fam. |  | F | 
|  |  uniflorus (1 Taxon + 1 Syn.) |  |  |  |  | 
|  | uniglumis, Eleocharis \ Einspelzige Sumpfbinse / Spike Rush |  | Cyperaceae \ Sauergräser / Sedge Fam. |  | D 
IRL | 
|  | unisiliquosa subsp. biflora, Hippocrepis −−> Hippocrepis biflora |  | Fabaceae \ Schmetterlingsblütler / Legumes |  | I 
Mal | 
|  | unisiliquosa, Hippocrepis \ Einhülsiger Hufeisenklee / One-Flowered Horseshoe Vetch |  | Fabaceae \ Schmetterlingsblütler / Legumes |  | Chi 
D 
Rho | 
|  |  uplandicum (1 Taxon + 1 Syn.) |  |  |  |  | 
|  |  urbanum (3 Taxa) |  |  |  |  | 
|  | urbica var. rhombifolia, Oxybasis −−> Chenopodium rhombifolium |  | Chenopodiaceae \ Gänsefußgew. / Goosefoot Fam.
 |  | D | 
|  | urbica, Oxybasis −−> Chenopodium urbicum |  | Chenopodiaceae \ Gänsefußgew. / Goosefoot Fam.
 |  | D | 
|  | urbicum var. intermedium, Chenopodium −−> Chenopodium rhombifolium |  | Chenopodiaceae \ Gänsefußgew. / Goosefoot Fam.
 |  | D | 
|  | urbicum, Chenopodium \ Ruten-Gänsefuß, Straßen-Gänsefuß / City Goosefoot |  | Chenopodiaceae \ Gänsefußgew. / Goosefoot Fam.
 |  | D | 
|  | urceolata, Polysiphonia \ Zarter Fadentang / Pitcher Siphon Weed ? |  | Rhodophytina \ Rot-Algen / Red Algae |  | S | 
|  |  urens (3 Taxa) |  |  |  |  | 
|  | urrielense, Helianthemum \ Urriellu-Sonnenröschen / Mount Urriellu Rock-Rose |  | Cistaceae \ Zistrosengew. / Rockrose Fam. |  | E | 
|  | ursinum, Allium \ Bär-Lauch / Ramsons |  | Liliaceae \ Liliengewächse / Lily Fam. |  | D 
F | 
|  |  urticifolia (1 Taxon + 1 Syn.) |  |  |  |  | 
|  | urvillei, Knautia integrifolia subsp. \ Urvilles Witwenblume / Urville's Widow Flower |  | Dipsacaceae \ Kardengewächse / Teasel Fam. |  | Rho | 
|  | usitatissimum, Linum \ Echter Lein / Flax |  | Linaceae \ Leingewächse / Linseed Fam. |  | A 
D | 
|  |  utriculata (1 Taxon + 1 Syn.) |  |  |  |  | 
|  | utriculosa, Gentiana \ Schlauch-Enzian / Bladder Gentian |  | Gentianaceae \ Enziangew. / Gentian Fam. |  | D 
HR 
I 
SLO | 
|  | uva-crispa, Ribes \ Stachelbeere / Gooseberry |  | Saxifragaceae \ Steinbrechgew. / Saxifrage Fam. |  | D 
F 
GR 
S | 
|  | uva-ursi, Arctostaphylos \ Immergrüne Bärentraube / Bearberry |  | Ericaceae \ Heidekrautgew. / Heather Fam. |  | E 
F 
HR 
S | 
|  | 
|  | 
|  | 
|  | 
|  | 
|  | 
|  |