| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| ROSA3 | Rosa sayi Schwein. | Rosa acicularis ssp. sayi | Rosaceae
|
| ROSE3 | Rosa sempervirens L. | evergreen rose | Rosaceae
|
| ROSE8 | Rosa serafinii Viviani | Mediterranean rose | Rosaceae
|
| ROSE5 | Rosa serrulata Raf. | Rosa carolina var. carolina | Rosaceae
|
| ROSES2 | Rosa setigera Michx. var. serena Palmer & Steyermark | Rosa setigera var. setigera | Rosaceae
|
| ROSES | Rosa setigera Michx. var. setigera | climbing rose | Rosaceae
|
| ROSET | Rosa setigera Michx. var. tomentosa Torr. & Gray | climbing rose | Rosaceae
|
| ROSE2 | Rosa setigera Michx. | climbing rose | Rosaceae
|
| ROSO | Rosa sonomensis Greene | Rosa spithamea var. sonomensis | Rosaceae
|
| ROSPA | Rosa spaldingii Cr�pin var. alta (Suksdorf) G.N. Jones | Rosa nutkana var. hispida | Rosaceae
|
| ROSPH | Rosa spaldingii Cr�pin var. hispida (Fern.) G.N. Jones | Rosa nutkana var. hispida | Rosaceae
|
| ROSPP | Rosa spaldingii Cr�pin var. parkeri (S. Wats.) St. John | Rosa nutkana var. hispida | Rosaceae
|
| ROSP7 | Rosa spaldingii Cr�pin | Rosa nutkana var. hispida | Rosaceae
|
| ROSP2 | Rosa spinosissima L. | Scotch rose | Rosaceae
|
| ROSPS3 | Rosa spithamea S. Wats. var. solitaria Henderson | Rosa spithamea var. spithamea | Rosaceae
|
| ROSPS | Rosa spithamea S. Wats. var. sonomensis (Greene) Jepson | Sonoma ground rose | Rosaceae
|
| ROSPS2 | Rosa spithamea S. Wats. var. spithamea | ground rose | Rosaceae
|
| ROSP3 | Rosa spithamea S. Wats. | ground rose | Rosaceae
|
| ROST4 | Rosa standleyi Rydb. | Rosa woodsii var. woodsii | Rosaceae
|
| ROSTA | Rosa stellata Woot. ssp. abyssa A. Phillips | desert rose | Rosaceae
|
| ROSTE2 | Rosa stellata Woot. ssp. mirifica (Greene) W.H. Lewis var. erlansoniae W.H. Lewis | desert rose | Rosaceae
|
| ROSTM2 | Rosa stellata Woot. ssp. mirifica (Greene) W.H. Lewis var. mirifica (Greene) Cockerell | desert rose | Rosaceae
|
| ROSTM | Rosa stellata Woot. ssp. mirifica (Greene) W.H. Lewis | desert rose | Rosaceae
|
| ROSTS | Rosa stellata Woot. ssp. stellata | desert rose | Rosaceae
|
| ROSTA2 | Rosa stellata Woot. var. abyssa (A. Phillips) N. Holmgren | Rosa stellata ssp. abyssa | Rosaceae
|
| ROST | Rosa stellata Woot. | desert rose | Rosaceae
|
| ROSU8 | Rosa subblanda Rydb. | Rosa blanda var. blanda | Rosaceae
|
| ROSU5 | Rosa subserrulata Rydb. | Rosa carolina var. carolina | Rosaceae
|
| ROSUR | Rosa suffulta Greene var. relicta (Erlanson) Deam | Rosa arkansana var. suffulta | Rosaceae
|
| ROSU6 | Rosa suffulta Greene | Rosa arkansana var. suffulta | Rosaceae
|
| ROTE4 | Rosa terrens Lunell | Rosa woodsii var. woodsii | Rosaceae
|
| ROTE3 | Rosa texarkana Rydb. | Rosa carolina var. carolina | Rosaceae
|
| ROTOG | Rosa tomentosa Sm. var. globulosa Rouy | Rosa tomentosa | Rosaceae
|
| ROTO | Rosa tomentosa Sm. | whitewoolly rose | Rosaceae
|
| ROUL | Rosa ultramontana (S. Wats.) Heller | Rosa woodsii var. ultramontana | Rosaceae
|
| ROVI80 | Rosa villosa L. | apple rose | Rosaceae
|
| ROVIL | Rosa virginiana P. Mill. var. lamprophylla (Rydb.) Fern. | Virginia rose | Rosaceae
|
| ROVIV2 | Rosa virginiana P. Mill. var. virginiana | Virginia rose | Rosaceae
|
| ROVI2 | Rosa virginiana P. Mill. | Virginia rose | Rosaceae
|
| ROWI | Rosa wichuraiana Cr�pin | memorial rose | Rosaceae
|
| ROWI2 | Rosa williamsii Fern. | Rosa blanda var. blanda | Rosaceae
|
| ROWOU2 | Rosa woodsii Lindl. ssp. ultramontana (S. Wats.) Taylor & MacBryde | Rosa woodsii var. ultramontana | Rosaceae
|
| ROWOA2 | Rosa woodsii Lindl. var. adenosepala (Woot. & Standl.) W.C. Martin & C.R. Hutchins | Rosa woodsii var. woodsii | Rosaceae
|
| ROWOA | Rosa woodsii Lindl. var. arizonica (Rydb.) W.C. Martin & C.R. Hutchins | Rosa woodsii var. ultramontana | Rosaceae
|
| ROWOF | Rosa woodsii Lindl. var. fendleri (Cr�pin) Rydb. | Rosa woodsii var. woodsii | Rosaceae
|
| ROWOG | Rosa woodsii Lindl. var. glabrata (Parish) Cole | Woods' rose | Rosaceae
|
| ROWOG3 | Rosa woodsii Lindl. var. granulifera (Rydb.) W.C. Martin & C.R. Hutchins | Rosa woodsii var. ultramontana | Rosaceae
|
| ROWOG2 | Rosa woodsii Lindl. var. gratissima (Greene) Cole | Tehachapi rose | Rosaceae
|
| ROWOH | Rosa woodsii Lindl. var. hypoleuca (Woot. & Standl.) W.C. Martin & C.R. Hutchins | Rosa woodsii var. woodsii | Rosaceae
|
| ROWOM | Rosa woodsii Lindl. var. macounii (Greene) W.C. Martin & C.R. Hutchins | Rosa woodsii var. woodsii | Rosaceae
|
| ROWOU | Rosa woodsii Lindl. var. ultramontana (S. Wats.) Jepson | Woods' rose | Rosaceae
|
| ROWOW | Rosa woodsii Lindl. var. woodsii | Woods' rose | Rosaceae
|
| ROWO | Rosa woodsii Lindl. | Woods' rose | Rosaceae
|
| ROXA2 | Rosa xanthina Lindl. | | Rosaceae
|
| ROYA | Rosa yainacensis Greene | Cascade rose | Rosaceae
|
| ROSA5 | Rosa L. | rose | Rosaceae
|
| RONE3 | Roselliniella nephromatis (Crouan) Matzer & Hafellner | | Uncertain Lichen Family
|
| ROSEL2 | Roselliniella Vainio | roselliniella | Uncertain Lichen Family
|
| ROGE | Roselliniopsis gelidaria (Mudd) Matzer & Hafellner | | Uncertain Lichen Family
|
| ROSEL | Roselliniopsis Matzer & Hafellner | roselliniopsis | Uncertain Lichen Family
|
| ROKA | Rosellinula kalbii (Hafellner) Hafellner & R. W. Rogers | | Uncertain Lichen Family
|
| ROSEL3 | Rosellinula R. Sant. | rosellinula | Uncertain Lichen Family
|
| RODO | Roseodendron donnell-smithii (Rose) F. Miranda | Tabebuia donnell-smithii | Bignoniaceae
|
| ROOF | Rosmarinus officinalis L. | rosemary | Lamiaceae
|
| ROSMA | Rosmarinus L. | rosemary | Lamiaceae
|
| ROCR3 | Rostraria cristata (L.) Tzvelev | Mediterranean hairgrass | Poaceae
|
| ROSTR | Rostraria Trin. | hairgrass | Poaceae
|
| ROCA5 | Rotala catholica (Cham. & Schlecht.) van Leeuwen | Rotala ramosior | Lythraceae
|
| RODE3 | Rotala dentifera (Gray) Koehne | Rotala ramosior | Lythraceae
|
| ROIN3 | Rotala indica (Willd.) Koehne | Indian toothcup | Lythraceae
|
| RORAI | Rotala ramosior (L.) Koehne var. interior Fern. & Grisc. | Rotala ramosior | Lythraceae
|
| RORAT | Rotala ramosior (L.) Koehne var. typica Fern. & Grisc. | Rotala ramosior | Lythraceae
|
| RORA | Rotala ramosior (L.) Koehne | lowland rotala | Lythraceae
|
| ROTAL | Rotala L. | rotala | Lythraceae
|
| ROFL4 | Rotantha floridana (S. Wats. ex Gray) Small | Campanula floridana | Campanulaceae
|
| RORO4 | Rotantha robinsiae (Small) Small | Campanula robinsiae | Campanulaceae
|
| ROCO5 | Rothrockia cordifolia Gray | Matelea cordifolia | Asclepiadaceae
|
| ROAL7 | Rottboellia altissima Poiret | Hemarthria altissima | Poaceae
|
| ROCO6 | Rottboellia cochinchinensis (Lour.) W.D. Clayton | itchgrass | Poaceae
|
| ROCY | Rottboellia cylindrica Willd. | Hainardia cylindrica | Poaceae
|
| ROEX2 | Rottboellia exaltata (L.) L. f. | Rottboellia cochinchinensis | Poaceae
|
| ROSA4 | Rottboellia sanguinea Retz. | Schizachyrium sanguineum var. sanguineum | Poaceae
|
| ROTTB | Rottboellia L. f. | itchgrass | Poaceae
|
| ROMU4 | Roubieva multifida (L.) Moq. | Chenopodium multifidum | Chenopodiaceae
|
| ROSU4 | Rourea surinamensis Miq. | Juan Caliente | Connaraceae
|
| ROURE | Rourea Aubl. | rourea | Connaraceae
|
| ROHU | Rousselia humilis (Sw.) Urban | shineseed | Urticaceae
|
| ROUSS | Rousselia Gaud. | rousselia | Urticaceae
|
| ROBO | Roystonea borinquena O.F. Cook | Puerto Rico royal palm | Arecaceae
|
| ROEL | Roystonea elata (Bartr.) F. Harper | Florida royal palm | Arecaceae
|
| ROFL3 | Roystonea floridana O.F. Cook | Roystonea elata | Arecaceae
|
| RORE2 | Roystonea regia auct. non (Kunth) O.F. Cook | Roystonea elata | Arecaceae
|
| ROYST | Roystonea O.F. Cook | royal palm | Arecaceae
|
| RUOD2 | Rubacer odoratus (L.) Rydb. | Rubus odoratus var. odoratus | Rosaceae
|
| RUPA18 | Rubacer parviflorus (Nutt.) Rydb. | Rubus parviflorus var. parviflorus | Rosaceae
|
| RUBR7 | Rubia brownei Michx., non R. Br. | Galium hispidulum | Rubiaceae
|
| RUPE12 | Rubia peregrina Walt., non L. | Galium hispidulum | Rubiaceae
|
| RUTI | Rubia tinctoria L. | madder | Rubiaceae
|
| RUTI2 | Rubia tinctorum L. | madder | Rubiaceae
|
| RUWA2 | Rubia walteri DC. | Galium hispidulum | Rubiaceae
|
| RUBIA | Rubia L. | rubia | Rubiaceae
|