| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| REHEH | Reboulia hemisphaerica (L.) Raddi ssp. hemisphaerica | | Aytoniaceae
|
| REHE | Reboulia hemisphaerica (L.) Raddi | | Aytoniaceae
|
| REBOU | Reboulia Raddi nom. cons. | | Aytoniaceae
|
| REBUT | Rebutia K. Schum. | rebutia | Cactaceae
|
| RECR | Rechingeria cribellifera (Nyl.) Servit | Lichinella cribellifera | Lichinaceae
|
| REFR | Rectanthera fragrans (Lindl.) O. Deg. | Callisia fragrans | Commelinaceae
|
| REBE | Rectolejeunea berteroana (Gottsche) A. Evans | | Lejeuneaceae
|
| REBR | Rectolejeunea brittoniae A. Evans | | Lejeuneaceae
|
| REEV | Rectolejeunea evansiana R. M. Schust. | | Lejeuneaceae
|
| REMA4 | Rectolejeunea maxonii A. Evans | | Lejeuneaceae
|
| REPH2 | Rectolejeunea phyllobola (Nees & Mont.) A. Evans | | Lejeuneaceae
|
| REPI2 | Rectolejeunea pililoba (Spruce) R. M. Schust. | | Lejeuneaceae
|
| RESP | Rectolejeunea spiniloba (Lindenb. & Gottsche) R. M. Schust. | | Lejeuneaceae
|
| RECTO | Rectolejeunea A. Evans | | Lejeuneaceae
|
| REFL | Redfieldia flexuosa (Thurb.) Vasey | blowout grass | Poaceae
|
| REDFI | Redfieldia Vasey | blowout grass | Poaceae
|
| REPE | Refractohilum peltigerae (Keissler) D. Hawksw. | | Uncertain Lichen Family
|
| REFRA | Refractohilum D. Hawksw. | refractohilum | Uncertain Lichen Family
|
| REFL2 | Rehsonia floribunda (Willd.) Stritch | Wisteria floribunda | Fabaceae
|
| RESI | Rehsonia sinensis (Sims) Stritch | Wisteria sinensis | Fabaceae
|
| REPI | Reichardia picroides (L.) Roth | common brighteyes | Asteraceae
|
| RETI | Reichardia tingitana (L.) Roth | false sowthistle | Asteraceae
|
| REICH | Reichardia Roth | brighteyes | Asteraceae
|
| REOL2 | Reimaria oligostachya Munro ex Benth. | Reimarochloa oligostachya | Poaceae
|
| REOL | Reimarochloa oligostachya (Munro ex Benth.) A.S. Hitchc. | Florida reimar grass | Poaceae
|
| REIMA | Reimarochloa A.S. Hitchc. | reimar grass | Poaceae
|
| REPA | Reinkella parishii Hasse | | Roccellaceae
|
| RESU | Reinkella subcrustacea Rasanen | Reinkella parishii | Roccellaceae
|
| REINK | Reinkella Darbish. | reinkella | Roccellaceae
|
| REMI | Relbunium microphyllum (Gray) Hemsl. | Galium microphyllum | Rubiaceae
|
| REAB | Relicina abstrusa (Vainio) Hale | | Parmeliaceae
|
| REEX2 | Relicina eximbricata (Gyelnik) Hale | | Parmeliaceae
|
| RELIC | Relicina (Hale & Kurok.) Hale | relicina | Parmeliaceae
|
| REMA3 | Remirea maritima Aubl. | beachstar | Cyperaceae
|
| REMIR | Remirea Aubl. | beachstar | Cyperaceae
|
| REKAM2 | Remya kauaiensis Hbd. var. magnifica O. Deg. & Sherff | Remya kauaiensis | Asteraceae
|
| REKAM | Remya kauaiensis Hbd. var. magnifolia O. Deg. & Sherff | Remya kauaiensis | Asteraceae
|
| REKA | Remya kauaiensis Hbd. | Kauai remya | Asteraceae
|
| REMA2 | Remya mauiensis Hbd. | Maui remya | Asteraceae
|
| REMO | Remya montgomeryi W.L. Wagner & Herbst | Kalalau Valley remya | Asteraceae
|
| REMYA | Remya Hbd. ex Benth. | remya | Asteraceae
|
| REMO3 | Renanthera monachica Ames | | Orchidaceae
|
| RENAN | Renanthera Lour. | renanthera | Orchidaceae
|
| REAL2 | Renealmia alpinia (Rottb.) Maas | | Zingiberaceae
|
| REAN | Renealmia antillarua auct. non (Roemer & J.A. Schultes) Gagnepain | Renealmia jamaicensis var. puberula | Zingiberaceae
|
| REAR2 | Renealmia aromatica (Aubl.) Griseb. | Renealmia occidentalis | Zingiberaceae
|
| REEX | Renealmia exaltata L. f. | Renealmia alpinia | Zingiberaceae
|
| REJAP | Renealmia jamaicensis (Gaertn.) Horan. var. puberula (Gagnepain) Maas | narciso colorado | Zingiberaceae
|
| REJA | Renealmia jamaicensis (Gaertn.) Horan. | narciso colorado | Zingiberaceae
|
| REOC | Renealmia occidentalis (Sw.) Sweet | bijao | Zingiberaceae
|
| RERE | Renealmia recurvata L. | Tillandsia recurvata | Bromeliaceae
|
| REUS | Renealmia usneoides L. | Tillandsia usneoides | Bromeliaceae
|
| RENEA | Renealmia L. f. | renealmia | Zingiberaceae
|
| RESE2 | Requienella seminuda (Pers.:Fr.) Boise | | Pyrenulaceae
|
| RESU2 | Requienella subcollapsa (Ellis & Everhart) R. C. Harris | | Pyrenulaceae
|
| REQUI | Requienella Fabre | requienella | Pyrenulaceae
|
| REAL | Reseda alba L. | white upright mignonette | Resedaceae
|
| RELU | Reseda lutea L. | yellow mignonette | Resedaceae
|
| RELU2 | Reseda luteola L. | weld | Resedaceae
|
| REOD | Reseda odorata L. | garden mignonette | Resedaceae
|
| REPH | Reseda phyteuma L. | rampion mignonette | Resedaceae
|
| RESED | Reseda L. | mignonette | Resedaceae
|
| REMO2 | Retama monosperma (L.) Boiss. | bridal broom | Fabaceae
|
| RETAM | Retama Raf., nom. cons. | bridal broom | Fabaceae
|
| RERO | Reussia rotundifolia (L. f.) Castell. | reussia | Pontederiaceae
|
| REUSS | Reussia Endl. | reussia | Pontederiaceae
|
| RETR | Reutealis trisperma (Blanco) Airy Shaw | Philippine tung | Euphorbiaceae
|
| REUTE | Reutealis Airy Shaw | reutealis | Euphorbiaceae
|
| REAR | Reverchonia arenaria Gray | sand reverchonia | Euphorbiaceae
|
| REVER | Reverchonia Gray | reverchonia | Euphorbiaceae
|
| REDE | Reynoldsia degeneri Sherff | Reynoldsia sandwicensis | Araliaceae
|
| REHI | Reynoldsia hillebrandii Sherff | Reynoldsia sandwicensis | Araliaceae
|
| REHO | Reynoldsia hosakana Sherff | Reynoldsia sandwicensis | Araliaceae
|
| REHUB | Reynoldsia huehuensis Sherff var. brevipes Sherff | Reynoldsia sandwicensis | Araliaceae
|
| REHUI | Reynoldsia huehuensis Sherff var. intermedia Sherff | Reynoldsia sandwicensis | Araliaceae
|
| REHU | Reynoldsia huehuensis Sherff | Reynoldsia sandwicensis | Araliaceae
|
| RELA | Reynoldsia lanutoensis Hochr. | reynoldsia | Araliaceae
|
| REMAM | Reynoldsia mauiensis Sherff var. macrocarpa O. Deg. & Sherff | Reynoldsia sandwicensis | Araliaceae
|
| REMA | Reynoldsia mauiensis Sherff | Reynoldsia sandwicensis | Araliaceae
|
| REOB | Reynoldsia oblonga Sherff | Reynoldsia sandwicensis | Araliaceae
|
| RESAI | Reynoldsia sandwicensis Gray var. intercedens Sherff | Reynoldsia sandwicensis | Araliaceae
|
| RESAM | Reynoldsia sandwicensis Gray var. molokaiensis Sherff | Reynoldsia sandwicensis | Araliaceae
|
| RESA | Reynoldsia sandwicensis Gray | 'ohe makai | Araliaceae
|
| REVEL | Reynoldsia venusta Sherff var. lanaiensis Sherff | Reynoldsia sandwicensis | Araliaceae
|
| REVE | Reynoldsia venusta Sherff | Reynoldsia sandwicensis | Araliaceae
|
| REYNO | Reynoldsia Gray | reynoldsia | Araliaceae
|
| REGU | Reynosia guama Urban | guama | Rhamnaceae
|
| REKR | Reynosia krugii Urban | Krug's darlingplum | Rhamnaceae
|
| RESE | Reynosia septentrionalis Urban | darlingplum | Rhamnaceae
|
| REUN | Reynosia uncinata Urban | sloe | Rhamnaceae
|
| REYNO2 | Reynosia Griseb. | darlingplum | Rhamnaceae
|
| REBA | Reynoutria baldschuanica (Regel) Shinners | Polygonum baldschuanicum | Polygonaceae
|
| RECI | Reynoutria cilinodis (Michx.) Shinners | Polygonum cilinode | Polygonaceae
|
| RECO | Reynoutria convolvulus (L.) Shinners | Polygonum convolvulus var. convolvulus | Polygonaceae
|
| REJA2 | Reynoutria japonica Houtt. | Polygonum cuspidatum | Polygonaceae
|
| RESA2 | Reynoutria sachalinensis (F. Schmidt ex Maxim.) Nakai | Polygonum sachalinense | Polygonaceae
|
| RESCC | Reynoutria scandens (L.) Shinners var. cristata (Engelm. & Gray) Shinners | Polygonum scandens var. cristatum | Polygonaceae
|
| RESCD | Reynoutria scandens (L.) Shinners var. dumetorum (L.) Shinners | Polygonum scandens var. dumetorum | Polygonaceae
|
| RESC | Reynoutria scandens (L.) Shinners | Polygonum scandens var. scandens | Polygonaceae
|
| RHBI | Rhabdadenia biflora (Jacq.) Muell.-Arg. | mangrovevine | Apocynaceae
|
| RHCO6 | Rhabdadenia corallicola Small | Angadenia berteroi | Apocynaceae
|