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 capillare | Witchgrass | Poaceae |
| Panicum virgatum | Switchgrass | Poaceae |
| Parathelypteris simulata | Massachusetts Fern | Thelypteridaceae |
| Parietaria pensylvanica | Pennsylvania Pellitory | Urticaceae |
| Parnassia glauca | Fen Grass of Parnassus | Saxifragaceae |
| Parthenium integrifolium | Wild Quinine | Asteraceae |
| Parthenocissus inserta | Thicket Creeper | Vitaceae |
| Parthenocissus quinquefolia | Virginia Creeper | Vitaceae |
| Paspalum setaceum | Bead Grass | Poaceae |
| Paxistima canbyi | Canby's Mountain Lover | Celastraceae |
| Pedicularis canadensis | Wood Betony | Scrophulariaceae |
| Pedicularis lanceolata | Fen Betony | Scrophulariaceae |
| Pellaea atropurpurea | Purple Cliffbrake | Pteridaceae |
| Peltandra virginica | Arrow Arum | Araceae |
| Penstemon canescens | Appalachian Beard-tongue | Scrophulariaceae |
| Penstemon digitalis | Foxglove Beard-tongue | Scrophulariaceae |
| Penstemon grandiflorus | Large-flowered Beard-tongue | Scrophulariaceae |
| Penstemon hirsutus | Hairy Beard-tongue | Scrophulariaceae |
| Penstemon laevigatus | Eastern Smooth Beard-tongue | Scrophulariaceae |
| Penthorum sedoides | Ditch Stonecrop | Saxifragaceae |
| Persicaria amphibia | Water Smartweed | Polygonaceae |
| Persicaria arifolia | Halberd-leaved Tearthumb | Polygonaceae |
| Persicaria lapathifolia | Dock-leaved Smartweed | Polygonaceae |
| Persicaria pensylvanica | Pennsylvania Smartweed | Polygonaceae |
| Persicaria punctata | Dotted Smartweed | Polygonaceae |
| Persicaria sagittata | Arrow-leaved Smartweed | Polygonaceae |
| Persicaria virginiana | Jumpseed | Polygonaceae |
| Pleurozium schreberi | Schreber's Feathermoss | Hylocomiaceae |
| Phegopteris connectilis | Long Beech Fern | Thelypteridaceae |
| Phegopteris hexagonoptera | Broad Beech Fern | Thelypteridaceae |
| Philonotis fontana | Spring Apple Moss | Bartamiaceae |
| Phlox divaricata | Woodland Phlox | Polemoniaceae |
| Phlox glaberrima | Marsh Phlox | Polemoniaceae |
| Phlox maculata | Spotted Phlox | Polemoniaceae |
| Phlox paniculata | Garden 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 heterophylla | Clammy Ground Cherry | Solanaceae |
| Physalis virginiana | Lance-leaved Ground Cherry | Solanaceae |
| Phytolacca americana | Pokeweed | Phytolaccaceae |
| Physocarpus opulifolius | Eastern Ninebark | Rosaceae |
| Physostegia virginiana | Obedient Plant | Lamiaceae |
| Picea glauca | White Spruce | Pinaceae |
| Picea mariana | Black Spruce | Pinaceae |
| Picea rubens | Red Spruce | Pinaceae |
| Pilea fontana | Black-fruited Clearweed | Urticaceae |
| Pilea pumila | Clearweed | Urticaceae |
| Pinus banksiana | Jack Pine | Pinaceae |
| Pinus echinata | Shortleaf Pine | Pinaceae |
| Pinus palustris | Longleaf Pine | Pinaceae |
| Pinus pungens | Table Mountain Pine | Pinaceae |
| Pinus resinosa | Red Pine | Pinaceae |
| Pinus rigida | Pitch Pine | Pinaceae |
| Pinus strobus | White Pine | Pinaceae |
| Pinus virginiana | Virginia Pine | Pinaceae |
| Platanthera aquilonis | Northern Green Bog Orchid | Orchidaceae |
| Platanthera blephariglottis | White Fringed Orchid | Orchidaceae |
| Platanthera ciliaris | Yellow Fringed Orchid | Orchidaceae |
| Platanthera clavellata | Club Spur Orchid | Orchidaceae |
| Platanthera cristata | Orange Crested Orchid | Orchidaceae |
| Platanthera dilatata | White Bog Orchid | Orchidaceae |
| Platanthera flava | Northern Tubercled Orchid | Orchidaceae |
| Platanthera grandiflora | Large Purple Fringed Orchid | Orchidaceae |
| Platanthera huronensis | Lake Huron Bog Orchid | Orchidaceae |
| Platanthera integra | Yellow Fringeless Orchid | Orchidaceae |
| Platanthera lacera | Ragged Fringed Orchid | Orchidaceae |
| Platanthera leucophaea | Eastern Prairie Fringed Orchid | Orchidaceae |
| Platanthera macrophylla | Large-spurred Round-leaved Orchid | Orchidaceae |
| Platanthera psycodes | Lesser Purple Fringed Orchid | Orchidaceae |
| Platanus occidentalis | American Sycamore | Platanaceae |
| Pleurozium schreberi | Schreber's Feathermoss | Hylocomiaceae |
| Podophyllum peltatum | Mayapple | Berberidaceae |
| Podostemum ceratophyllum | Riverweed | Podostemaceae |
| Pogonia ophioglossoides | Rose Pogonia | Orchidaceae |
| Polanisia dodecandra | Clammy Weed | Cleomaceae |
| Polemonium reptans | Jacob's Ladder | Polemoniaceae |
| Polemonium vanbruntiae | Bog Jacob's Ladder | Polemoniaceae |
| Polygala brevifolia | Short-leaved Milkwort | Polygalaceae |
| Polygala cruciata | Cross-leaved Milkwort | Polygalaceae |
| Polygala lutea | Orange Milkwort | Polygalaceae |
| Polygala paucifolia | Fringed Polygala | Polygalaceae |
| Polygala polygama | Racemed Milkwort | Polygalaceae |
| Polygala sanguinea | Purple Milkwort | Polygalaceae |
| Polygala senega | Seneca Snakeroot | Polygalaceae |
| Polygonatum biflorum | Smooth Solomon's Seal | Liliaceae |
| Polygonatum pubescens | Hairy Solomon's Seal | Liliaceae |
| Polygonum articulatum | Northern Jointweed | Polygonaceae |
| Polygonum buxiforme | Small's Knotweed | Polygonaceae |
| Polymnia canadensis | Pale Leafcup | Asteraceae |
| Polypodium appalachianum | Appalachian Polypody | Polypodiaceae |
| 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 balsamifera | Balsam Poplar | Salicaceae |
| Populus deltoides | Eastern Cottonwood | Salicaceae |
| Populus grandidentata | Big-toothed Aspen | Salicaceae |
| Populus tremuloides | Trembling Aspen | Salicaceae |
| Potentilla anserina | Silverweed | Rosaceae |
| Potentilla canadensis | Dwarf Cinquefoil | Rosaceae |
| Potentilla fruticosa | Shrubby Cinquefoil | Rosaceae |
| Potentilla palustris | Marsh Cinquefoil | Rosaceae |
| Potentilla simplex | Common Cinquefoil | Rosaceae |
| Potamogeton nodosus | Long-leaved Pondweed | Potamogetonaceae |
| Prosartes lanuginosa | Yellow Fairybells | Liliaceae |
| Proserpinaca palustris | Marsh Mermaid Weed | Haloragaceae |
| Proserpinaca pectinata | Comb-leaved Mermaid Weed | Haloragaceae |
| Prunella vulgaris var. lanceolata | Self Heal | Lamiaceae |
| Prunus americana | American Plum | Rosaceae |
| Prunus maritima | Beach Plum | Rosaceae |
| Prunus pensylvanica | Pin Cherry | Rosaceae |
| Prunus pumila | Sand Cherry | Rosaceae |
| Prunus serotina | Wild Black Cherry | Rosaceae |
| Prunus virginiana | Chokecherry | Rosaceae |
| Pseudognaphalium macounii | Clammy Rabbit Tobacco | Asteraceae |
| Pseudognaphalium obtusifolium | Sweet Everlasting | Asteraceae |
| Psuedolycopodiella caroliniana | Carolina Bog Clubmoss | Lycopodiaceae |
| Ptelea trifoliata | Hoptree | Rutaceae |
| Pteridium aquilinum | Bracken Fern | Dennstaedtiaceae |
| Ptilium crista-castrensis | Knight's Plume Moss | Hypnaceae |
| Pycnanthemum incanum | Hoary Mountain Mint | Lamiaceae |
| Pycnanthemum muticum | Clustered Mountain Mint | Lamiaceae |
| Pycnanthemum verticillatum | Whorled Mountain Mint | Lamiaceae |
| Pycnanthemum virginianum | Virginia Mountain Mint | Lamiaceae |
| Pycnanthemum tenuifolium | Slender Mountain Mint | Lamiaceae |
| Pyrola americana | American Shinleaf | Ericaceae |
| Pyrola asarifolia | Pink Shinleaf | Ericaceae |
| Pyrola elliptica | Large-leaved Shinleaf | Ericaceae |
| Pyrola minor | Snowline Wintergreen | Ericaceae |
© 2004 Michael Hough