Index of plants by genus
| Species | Common Name | Family |
| Ranunculus abortivus | Small-flowered Buttercup | Ranunculaceae |
| Ranunculus fascicularis | Early Buttercup | Ranunculaceae |
| Ranunculus hispidus var. caricetorum | Northern Swamp Buttercup | Ranunculaceae |
| Ranunculus longirostris | White Water-crowfoot | Ranunculaceae |
| Ranunculus septentrionalis | Swamp Buttercup | Ranunculaceae |
| Ratibida pinnata | Yellow Coneflower | Asteraceae |
| Rhamnus alnifolia | Alder-leaved Buckthorn | Rhamnaceae |
| Rhamnus caroliniana | Carolina Buckthorn | Rhamnaceae |
| Rhododendron catawbiense | Catawba Rhododendron | Ericaceae |
| Rhododendron maximum | Rosebay Rhododendron | Ericaceae |
| Rhododendron prinophyllum | Early Azalea | Ericaceae |
| Rhododendron viscosum | Swamp Azalea | Ericaceae |
| Rhus aromatica | Fragrant Sumac | Anacardiaceae |
| Rhus copallinum | Winged Sumac | Anacardiaceae |
| Rhus glabra | Smooth Sumac | Anacardiaceae |
| Rhus typhina | Staghorn Sumac | Anacardiaceae |
| Rhynchospora alba | White Beak-rush | Cyperaceae |
| Rhynchospora glomerata | Clustered Beak-rush | Cyperaceae |
| Rhytidiadelphus triquestrus | Shaggy Moss | Hylocomiaceae |
| Ribes americanum | Eastern Black Currant | Grossulariaceae |
| Ribes cynosbati | Eastern Prickly Gooseberry | Grossulariaceae |
| Ribes glandulosum | Skunk Currant | Grossulariaceae |
| Ribes hirtellum | Hairy-stemmed Gooseberry | Grossulariaceae |
| Ribes missouriense | Missouri Gooseberry | Grossulariaceae |
| Ribes triste | Swamp Red Current | Grossulariaceae |
| Robinia hispida | Bristly Locust | Fabaceae |
| Robinia pseudoacacia | Black Locust | Fabaceae |
| Rorippa palustris | Common Yellow-cress | Brassicaceae |
| Rosa carolina | Carolina Rose | Rosaceae |
| Rosa palustris | Swamp Rose | Rosaceae |
| Rosa setigera | Illinois Rose | Rosaceae |
| Rosa virginiana | Virginia Rose | Rosaceae |
| Rubus allegheniensis | Allegheny Blackberry | Rosaceae |
| Rubus cuneifolius | Sand Blackberry | Rosaceae |
| Rubus flagellaris | Northern Dewberry | Rosaceae |
| Rubus hispidus | Swamp Dewberry | Rosaceae |
| Rubus idaeus ssp. strigosus | American Red Raspberry | Rosaceae |
| Rubus occidentalis | Black Raspberry | Rosaceae |
| Rubus pubescens | Dwarf Red Raspberry | Rosaceae |
| Rubus odoratus | Purple Flowering Raspberry | Rosaceae |
| Rubus setosus | Setose Blackberry | Rosaceae |
| Rudbeckia hirta | Black-eyed Susan | Asteraceae |
| Rudbeckia laciniata | Wild Golden Glow | Asteraceae |
| Rudbeckia triloba | Black-eyed Susan | Asteraceae |
| Ruellia humilis | Wild Petunia | Acanthaceae |
© 2004 Michael Hough