Weed Herbarium – by Scientific Name
| Ranunculus abortivus | smallflower buttercup | Ranunculaceae - Buttercup Family |
| Ranunculus acris | tall buttercup | Ranunculaceae - Buttercup Family |
| Ranunculus bulbosus | bulbous buttercup | Ranunculaceae - Buttercup Family |
| Ranunculus ficaria | lesser celadine | Ranunculaceae - Buttercup Family |
| Ranunculus repens | creeping buttercup | Ranunculaceae - Buttercup Family |
| Raphanus raphanistrum | wild radish | Brassicaceae (Cruciferae) - Mustard Family |
| Rhinanthus crista-galli | see - Rhinanthus minor | |
| Rhinanthus minor | yellow-rattle | Scrophulariaceae - Figwort Family |
| Rhus radicans | see - Toxicodendron radicans | |
| Rhus glabra | smooth sumac | Anacardiaceae - Cashew Family |
| Rhus typhina | staghorn sumac | Anacardiaceae - Cashew Family |
| Robinia hispida | bristly locust | Fabaceae (Leguminosae) - Pea or Bean Family |
| Rorippa palustris | marsh yellowcress | Brassicaceae (Cruciferae) - Mustard Family |
| Rorippa x prostrata | prostrate fieldcress | Brassicaceae (Cruciferae) - Mustard Family |
| Rosa multiflora | multiflora rose | Rosaceae - Rose Family |
| Rubus odoratus | purple-flowering raspberry | Rosaceae - Rose Family |
| Rubus phoenicolasius | wine raspberry wineberry | Rosaceae - Rose Family |
| Rudbeckia hirta | black-eyed susan | Asteraceae (Compositae) - Aster or Sunflower Family |
| Rumex acetosella | red sorrel | Polygonaceae - Smartweed or Buckwheat Family |
| Rumex crispus | curly dock | Polygonaceae - Smartweed or Buckwheat Family |
| Rumex obtusifolius | broadleaf dock | Polygonaceae - Smartweed or Buckwheat Family |