Index of plants by genus
| Species | Common Name | Family |
| Pachysandra procumbens | Alleghany Pachysandra | Buxaceae |
| Panax quinquefolius | American Ginseng | Araliaceae |
| Panax trifolius | Dwarf Ginseng | Araliaceae |
| Panicum virgatum | Switchgrass | Poaceae |
| Parnassia glauca | Fen Grass of Parnassus | Saxifragaceae |
| Parthenium integrifolium | Wild Quinine | Asteraceae |
| Parthenocissus inserta | Thicket Creeper | Vitaceae |
| Parthenocissus quinquefolia | Virginia Creeper | Vitaceae |
| Pedicularis canadensis | Wood Betony | Scrophulariaceae |
| Pedicularis lanceolata | Fen Betony | Scrophulariaceae |
| Pellaea atropurpurea | Purpe Cliffbrake | Pteridaceae |
| Peltandra virginica | Arrow Arum | Araceae |
| Penstemon canescens | Appalachian Beard-tongue | Scrophulariaceae |
| Penstemon digitalis | Foxglove Beard-tongue | Scrophulariaceae |
| Penstemon hirsutus | Hairy Beard-tongue | Scrophylariaceae |
| Penthorum sedoides | Ditch Stonecrop | Saxifragaceae |
| Pleurozium schreberi | Schreber's Feathermoss | Hylocomiaceae |
| Philonotis fontana | Spring Apple Moss | Bartamiaceae |
| Phlox divaricata | Woodland Phlox | Polemoniaceae |
| Phlox glaberrima | Marsh Phlox | Polemoniaceae |
| Phlox pilosa | Prairie Phlox | Polemoniaceae |
| Phlox subulata | Moss Phlox | Polemoniaceae |
| Phryma leptostachya | American Lopseed | Phrymaceae |
| Phyla lanceolata | Lance-leaved Fog-fruit | Verbenaceae |
| Physalis virginiana | Lance-leaved Ground Cherry | Solanaceae |
| Phytolacca americana | Pokeweed | Phytolaccaceae |
| Physocarpus opulifolius | Eastern Ninebark | Rosaceae |
| Physostegia virginiana | Obedient Plant | Lamiaceae |
| Picea mariana | Black Spruce | Pinaceae |
| Picea rubens | Red Spruce | Pinaceae |
| Pilea pumila | Clearweed | Urticaceae |
| Pinus banksiana | Jack Pine | Pinaceae |
| Pinus resinosa | Red Pine | Pinaceae |
| Pinus strobus | White Pine | Pinaceae |
| Platanthera blephariglottis | White Fringed Orchid | Orchidaceae |
| Platanthera clavellata | Green Wood Orchid | Orchidaceae |
| Platanthera hyperborea | Northern Green Orchid | Orchidaceae |
| Platanus occidentalis | Sycamore | Plantaceae |
| Pleurozium schreberi | Schreber's Feathermoss | Hylocomiaceae |
| Podophyllum peltatum | Mayapple | Berberidaceae |
| Pogonia ophioglossoides | Rose Pagonia | Orchidaceae |
| Polemonium reptans | Jacob's Ladder | Polemoniaceae |
| Polygonum amphibium | Water Smartweed | Polygonaceae |
| Polygonum sagittatum | Arrow-leaved Tearthumb | Polygonaceae |
| Polygonum virginianum | Jumpseed | Polygonaceae |
| Polygala paucifolia | Fringed Polygala | Polygalaceae |
| Polygala polygama | Racemed Milkwort | Polygalaceae |
| Polygala sanguinea | Purple Milkwort | Polygalaceae |
| Polygala senega | Seneca Snakeroot | Polygalaceae |
| Polymnia canadensis | Pale Leafcup | Asteraceae |
| Polygonatum canaliculatum | Smooth Solomon's Seal | Liliaceae |
| Polypodium virginianum | Rock Polypody | Polypodiaceae |
| Polystichum acrostichoides | Christmas Fern | Dryopteridaceae |
| Polytrichum juniperinum | Juniper Moss | Polytrichaceae |
| Polytrichum strictum | Polytrichum Moss | Polytrichaceae |
| Pontederia cordata | Pickerelweed | Pontederiaceae |
| Populus deltoides | Eastern Cottonwood | Salicaceae |
| Populus grandidentata | Big-toothed Aspen | Salicaceae |
| Populus tremuloides | Trembling Aspen | Salicaceae |
| Potentilla anserina | Silverweed | Rosaceae |
| Potentilla fruticosa | Shrubby Cinquefoil | Rosaceae |
| Potentilla palustris | Marsh Cinquefoil | Rosaceae |
| Potentilla simplex | Common Cinquefoil | Rosaceae |
| Potamogeton ampifolius | Large-leaved Pondweed | Potamogetonaceae |
| Potamogeton gramineus | Grass-leaved Pondweed | Potamogetonaceae |
| Potamogeton nodosus | Long-leaved Pondweed | Potamogetonaceae |
| Potamogeton pectinatus | Sago Pondweed | Potamogetonaceae |
| Potamogeton robbinsii | Robin's Fernleaf | Potamogetonaceae |
| Prenanthes altissima | Tall White Lettuce | Asteraceae |
| Prunella vulgaris var. lanceolata | Self Heal | Lamiaceae |
| Prunus americana | American Plum | Rosaceae |
| Prunus pensylvanica | Pin Cherry | Rosaceae |
| Prunus pumila | Sand Cherry | Rosaceae |
| Prunus serotina | Wild Black Cherry | Rosaceae |
| Prunus virginiana | Chokecherry | Rosaceae |
| Ptelea trifoliata | Hoptree | Rutaceae |
| Pteridium aquilinum | Bracken Fern | Dennstaedtiaceae |
| Ptilium crista-castrensis | Knight's Plume Moss | Hypnaceae |
| Pycnanthemum virginianum | Virginia Mountain Mint | Lamiaceae |
| Pycnanthemum tenuifolium | Slender Mountain Mint | Lamiaceae |
| Pyrola elliptica | Large-leaved Shinleaf | Pyrolaceae |
© 2004 Michael Hough