| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| ROBIN | Robinia L. | locust | Fabaceae
|
| ROHA2 | Robinsonia haldaniana (Grev.) Crum | Callicladium haldanianum | Hypnaceae
|
| ROBA2 | Roccella babingtonii Mont. | | Roccellaceae
|
| RODE4 | Roccella decipiens Darbish. | | Roccellaceae
|
| RODI | Roccella difficilis Darbish. | | Roccellaceae
|
| ROFI | Roccella fimbriata Darbish. | | Roccellaceae
|
| ROFU | Roccella fuciformis (L.) DC. | | Roccellaceae
|
| ROLE2 | Roccella leucophaea Tuck. | Dendrographa leucophaea | Roccellaceae
|
| ROMO4 | Roccella montagnei Bel. | | Roccellaceae
|
| ROPE3 | Roccella peruensis Krempelh. | | Roccellaceae
|
| ROPH | Roccella phycopsis (Ach.) Ach. | | Roccellaceae
|
| ROTI | Roccella tinctoria DC. | | Roccellaceae
|
| ROCCE | Roccella DC. | roccella | Roccellaceae
|
| ROCO11 | Roccellina conformis Tehler | | Roccellaceae
|
| ROFR2 | Roccellina franciscana (Zahlbr. ex Herre) Follmann | | Roccellaceae
|
| ROCCE2 | Roccellina Darbish. | roccellina | Roccellaceae
|
| ROAC2 | Rochefortia acanthophora (DC.) Griseb. | greenheart ebony | Boraginaceae
|
| ROCU3 | Rochefortia cuneata Sw. | Rochefortia spinosa | Boraginaceae
|
| ROSP8 | Rochefortia spinosa (Jacq.) Urban | espino | Boraginaceae
|
| ROCHE | Rochefortia Sw. | rochefortia | Boraginaceae
|
| ROALG | Roegneria albicans (Scribn. & J.G. Sm.) Beetle var. griffithii (Scribn. & J.G. Sm. ex Piper) Beetle | Elymus albicans | Poaceae
|
| ROAL4 | Roegneria albicans (Scribn. & J.G. Sm.) Beetle | Elymus albicans | Poaceae
|
| ROBOH | Roegneria borealis (Turcz.) Nevski var. hyperarctica (Polunin) Melderis | Elymus hyperarcticus | Poaceae
|
| ROCI3 | Roegneria ciliaris (Trin.) Nevski | Elymus ciliaris | Poaceae
|
| ROHY | Roegneria hyperarctica (Polunin) Tzvelev | Elymus hyperarcticus | Poaceae
|
| ROPA7 | Roegneria pauciflora (Schwein.) Hyl. | Elymus trachycaulus ssp. trachycaulus | Poaceae
|
| ROPE5 | Roegneria pendulina Nevski | Elymus pendulina | Poaceae
|
| ROSP6 | Roegneria spicata (Pursh) Beetle | Pseudoroegneria spicata ssp. spicata | Poaceae
|
| ROTR4 | Roegneria trachycaula (Link) Nevski | Elymus trachycaulus ssp. trachycaulus | Poaceae
|
| ROTU3 | Roegneria turczaninovii (Drob.) Nevski | Elymus gmelinii | Poaceae
|
| ROVI4 | Roegneria violacea (Hornem.) Melderis | Elymus alaskanus ssp. latiglumis | Poaceae
|
| RORO5 | Roellia roellii (Broth. in R�ll) Andrews ex Crum | Roell's moss | Bryaceae
|
| ROSI3 | Roellia simplex Kindb. | Roellia roellii | Bryaceae
|
| ROELL | Roellia Kindb. | Roell's moss | Bryaceae
|
| RORE | Roemeria refracta DC. | spotted Asian poppy | Papaveraceae
|
| ROEME | Roemeria Medik. | roemeria | Papaveraceae
|
| ROFR | Rolandra fruticosa (L.) Kuntze | yerba de plata | Asteraceae
|
| ROLAN | Rolandra Rottb. | yerba de plata | Asteraceae
|
| ROCA12 | Roldana carlomasonii (B.L. Turner & T.M. Barkl.) C. Jeffrey | Roldana hartwegii | Asteraceae
|
| ROHA3 | Roldana hartwegii (Benth.) H.E. Robins. & Brett. | Hartweg's groundsel | Asteraceae
|
| ROLDA | Roldana Llave ex Lex. | groundsel | Asteraceae
|
| ROAM5 | Rollandia ambigua G. Don | rollandia | Campanulaceae
|
| ROANO | Rollandia angustifolia (Hbd.) Rock var. ochreata F. Wimmer | Cyanea koolauensis | Campanulaceae
|
| ROAN | Rollandia angustifolia (Hbd.) Rock | Cyanea koolauensis | Campanulaceae
|
| ROBI | Rollandia bidentata St. John | Cyanea calycina | Campanulaceae
|
| ROCAK | Rollandia calycina (Cham.) G. Don var. kaalae (Wawra) F. Wimmer | Cyanea calycina | Campanulaceae
|
| ROCA7 | Rollandia calycina (Cham.) G. Don | Cyanea calycina | Campanulaceae
|
| ROCRM | Rollandia crispa Gaud. var. muricata Rock | Cyanea crispa | Campanulaceae
|
| ROCR | Rollandia crispa Gaud. | Cyanea crispa | Campanulaceae
|
| RODE6 | Rollandia degeneriana F. Wimmer p.p. | Cyanea lanceolata | Campanulaceae
|
| RODE6 | Rollandia degeneriana F. Wimmer p.p. | Cyanea longiflora | Campanulaceae
|
| ROHU2 | Rollandia humboldtiana Gaud. | Cyanea humboldtiana | Campanulaceae
|
| ROLAC | Rollandia lanceolata Gaud. ssp. calycina (Cham.) Lammers | Cyanea calycina | Campanulaceae
|
| ROLAB | Rollandia lanceolata Gaud. var. brevipes F. Wimmer | Cyanea longiflora | Campanulaceae
|
| ROLAG | Rollandia lanceolata Gaud. var. glaberrima F. Wimmer | Cyanea lanceolata | Campanulaceae
|
| ROLAK | Rollandia lanceolata Gaud. var. kipapaensis Hosaka | Cyanea lanceolata | Campanulaceae
|
| ROLAR | Rollandia lanceolata Gaud. var. rockii St. John & Hosaka | Cyanea lanceolata | Campanulaceae
|
| ROLAT | Rollandia lanceolata Gaud. var. tomentella (Wawra) F. Wimmer | Cyanea calycina | Campanulaceae
|
| ROLAV | Rollandia lanceolata Gaud. var. viridiflora Rock | Cyanea lanceolata | Campanulaceae
|
| ROLA2 | Rollandia lanceolata Gaud. | Cyanea lanceolata | Campanulaceae
|
| ROLO | Rollandia longiflora Wawra | Cyanea longiflora | Campanulaceae
|
| ROPA3 | Rollandia parvifolia Forbes | Cyanea parvifolia | Campanulaceae
|
| ROPI5 | Rollandia pinnatifida (Cham.) G. Don | Cyanea pinnatifida | Campanulaceae
|
| ROPU | Rollandia purpurellifolia Rock | Cyanea purpurellifolia | Campanulaceae
|
| ROSE4 | Rollandia sessilifolia O. Deg. | Cyanea sessilifolia | Campanulaceae
|
| ROST2 | Rollandia st.-johnii Hosaka | Cyanea st.-johnii | Campanulaceae
|
| ROWA2 | Rollandia waianaeensis St. John | Cyanea calycina | Campanulaceae
|
| ROLLA | Rollandia Gaud. | rollandia | Campanulaceae
|
| RODE5 | Rollinia deliciosa Saff. | Rollinia pulchrinervis | Annonaceae
|
| ROMU3 | Rollinia mucosa (Jacq.) Baill. | wild sugar apple | Annonaceae
|
| ROPU3 | Rollinia pulchrinervis A. DC. | biriba | Annonaceae
|
| ROLLI | Rollinia St.-Hil. | rollinia | Annonaceae
|
| ROCA6 | Romanzoffia californica Greene | California mistmaiden | Hydrophyllaceae
|
| ROSI | Romanzoffia sitchensis Bong. | Sitka mistmaiden | Hydrophyllaceae
|
| ROSU7 | Romanzoffia suksdorfii Greene | Romanzoffia californica | Hydrophyllaceae
|
| ROTH | Romanzoffia thompsonii V.M. Marttala | Thompson's mistmaiden | Hydrophyllaceae
|
| ROTR | Romanzoffia tracyi Jepson | Tracy's mistmaiden | Hydrophyllaceae
|
| ROUNG | Romanzoffia unalaschcensis Cham. var. glabriuscula Hult�n | Alaska mistmaiden | Hydrophyllaceae
|
| ROUNU | Romanzoffia unalaschcensis Cham. var. unalaschcensis | Alaska mistmaiden | Hydrophyllaceae
|
| ROUN | Romanzoffia unalaschcensis Cham. | Alaska mistmaiden | Hydrophyllaceae
|
| ROMAN | Romanzoffia Cham. | mistmaiden | Hydrophyllaceae
|
| ROCOT | Romneya coulteri Harvey var. trichocalyx (Eastw.) Jepson | Romneya trichocalyx | Papaveraceae
|
| ROCO | Romneya coulteri Harvey | Coulter's Matilija poppy | Papaveraceae
|
| ROTR2 | Romneya trichocalyx Eastw. | bristly Matilija poppy | Papaveraceae
|
| ROMNE | Romneya Harvey | Matilija poppy | Papaveraceae
|
| ROLO3 | Romulea longifolia (Salisb.) Baker | Romulea rosea var. australis | Iridaceae
|
| ROROA | Romulea rosea (L.) Ecklon var. australis (Ewart) de Vos | rosy sandcrocus | Iridaceae
|
| RORO | Romulea rosea (L.) Ecklon | rosy sandcrocus | Iridaceae
|
| ROMUL | Romulea Maratti | romulea | Iridaceae
|
| ROIN4 | Rondeletia inermis (Spreng.) Krug & Urban | cordobancillo | Rubiaceae
|
| ROMI7 | Rondeletia microdon DC. | Psychotria microdon | Rubiaceae
|
| ROPI3 | Rondeletia pilosa Sw. | cordobancillo peludo | Rubiaceae
|
| ROPO | Rondeletia portoricensis Krug & Urban | Juan Tomas | Rubiaceae
|
| RORE4 | Rondeletia repens L. | Geophila repens | Rubiaceae
|
| RONDE | Rondeletia L. | cordobancillo | Rubiaceae
|
| ROCH2 | Ropalospora chlorantha (Tuck.) S. Ekman | | Fuscideaceae
|
| ROHI5 | Ropalospora hibernica (P. James & Poelt) Tonsberg | | Fuscideaceae
|
| ROLU3 | Ropalospora lugubris (Sommerf.) Poelt | | Fuscideaceae
|
| ROVI5 | Ropalospora viridis (Tonsberg) Tonsberg | | Fuscideaceae
|
| ROPAL | Ropalospora A. Massal. | ropalospora | Fuscideaceae
|
| ROAL | Rorippa alpina (S. Wats.) Rydb. | alpine yellowcress | Brassicaceae
|