| To Codes in: | A | B | C | D | E | F | G | H | I | K | L | M | N | O | P | R | S | T | U | V | W | Z |
| REFL | Redfieldia flexuosa | blowout grass |
| REDFI | Redfieldia sp. | redfieldia |
| ROCR3 | Rostraria cristata | annual junegrass |
| ROSTR | Rostraria sp. | Rostraria |
| ROCO6 | Rottboellia cochinchinensis | itch grass |
| ROTTB | Rottboellia sp. | rottboellia |