Weed Herbarium – by Scientific Name
| Phragmites communis | see - Phragmites australis | |
| Phragmites australis | common reed | Poaceae (Graminae) - Grass Family |
| Phytolacca americana | common pokeweed | Phytolaccaceae - Pokeweed Family |
| Pilea pumila | clearweed | Urticaceae - Nettle Family |
| Plantago lanceolata | narrowleaf plantain | Plantaginaceae - Plantain Family |
| Plantago major | broadleaf plantain | Plantaginaceae - Plantain Family |
| Poa annua | annual bluegrass | Poaceae (Graminae) - Grass Family |
| Poa bulbosa | bulbous bluegrass | Poaceae (Graminae) - Grass Family |
| Polygonum virginianum | see - Tovara virginiana | |
| Polygonum arifolium | Halberd-leaved tearthumb | Polygonaceae - Smartweed or Buckwheat Family |
| Polygonum aviculare | prostrate knotweed | Polygonaceae - Smartweed or Buckwheat Family |
| Polygonum cilinode | black fringed knotweed | Polygonaceae - Smartweed or Buckwheat Family |
| Polygonum convolvulus | wild buckwheat | Polygonaceae - Smartweed or Buckwheat Family |
| Polygonum cuspidatum | Japanese knotweed | Polygonaceae - Smartweed or Buckwheat Family |
| Polygonum pensylvanicum | Pennsylvania smartweed | Polygonaceae - Smartweed or Buckwheat Family |
| Polygonum persicaria | lady's thumb smartweed | Polygonaceae - Smartweed or Buckwheat Family |
| Polygonum sachalinense | giant knotweed | Polygonaceae - Smartweed or Buckwheat Family |
| Polygonum sagittatum | arrowleaf tear-thumb | Polygonaceae - Smartweed or Buckwheat Family |
| Polygonum scandens | hedge smartweed | Polygonaceae - Smartweed or Buckwheat Family |
| Portulaca oleracea | common purslane | Portulacaceae - Purslane Family |
| Potentilla argentea | silvery cinquefoil | Rosaceae - Rose Family |
| Potentilla norvegica | rough cinquefoil | Rosaceae - Rose Family |
| Potentilla recta | sulfur cinquefoil | Rosaceae - Rose Family |
| Potentilla simplex | old field cinquefoil | Rosaceae - Rose Family |
| Prunella vulgaris | heal-all | Lamiaceae (Labiatae) - Mint Family |
| Pteridium aquilinum | bracken fern | Polypodiaceae - Fern Family |
| Pueraria lobata | see - Pueraria montana | |
| Pueraria montana | kudzu | Fabaceae (Leguminosae) - Pea or Bean Family |
| 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 |
| Sagina procumbens | birdseye pearlwort | Caryophyllaceae - Pink Family |