P
- Pachysandra terminalis (I)
- Packera anonyma (N)
- Packera aurea (N)
- Packera glabella (N)
- Packera obovata (N)
- Packera paupercula (N)
- Packera plattensis (N)
- Panax quinquefolius (N)
- Panax trifolius (N)
- Panicum anceps (N)
- Panicum capillare (N)
- Panicum dichotomiflorum var. dichotomiflorum (N)
- Panicum flexile (N)
- Panicum gattingeri (N)
- Panicum miliaceum ssp. miliaceum (I)
- Panicum philadelphicum (N)
- Panicum rigidulum var. elongatum (N)
- Panicum rigidulum var. pubescens (N)
- Panicum rigidulum var. rigidulum (N)
- Panicum verrucosum (N)
- Panicum virgatum var. virgatum (N)
- Papaver argemone (I)
- Papaver dubium (I)
- Papaver rhoeas (I)
- Papaver somniferum (I)
- Parietaria pensylvanica (N)
- Parnassia glauca (N)
- Paronychia canadensis (N)
- Paronychia fastigiata var. fastigiata (N)
- Parthenium hysterophorus (I)
- Parthenium integrifolium var. integrifolium (N)
- Parthenocissus quinquefolia (N)
- Parthenocissus tricuspidata (I)
- Parthenocissus vitacea (N)
- Pascopyrum smithii (N)
- Paspalum floridanum (N)
- Paspalum fluitans (N)
- Paspalum laeve (N)
- Paspalum pubiflorum (N)
- Paspalum setaceum (N)
- Passiflora incarnata (N)
- Passiflora lutea (N)
- Pastinaca sativa (I)
- Paulownia tomentosa (I)
- Paxistima canbyi (N)
- Pedicularis canadensis ssp. canadensis (N)
- Pedicularis lanceolata (N)
- Pellaea atropurpurea (N)
- Pellaea glabella ssp. glabella (N)
- Peltandra virginica (N)
- Pennisetum glaucum (I)
- Penstemon alluviorum (N)
- Penstemon calycosus (N)
- Penstemon canescens (N)
- Penstemon cobaea (N)
- Penstemon digitalis (N)
- Penstemon grandiflorus (N)
- Penstemon hirsutus (N)
- Penstemon laevigatus (N)
- Penstemon pallidus (N)
- Penstemon tubiflorus var. tubiflorus (N)
- Penthorum sedoides (N)
- Perideridia americana (N)
- Perilla frutescens var. frutescens (I)
- Petasites hybridus (I)
- Petrorhagia prolifera (I)
- Petrorhagia saxifraga (I)
- Petroselinum crispum (I)
- Petunia × atkinsiana (I)
- Petunia axillaris (I)
- Phacelia bipinnatifida (N)
- Phacelia dubia var. dubia (N)
- Phacelia purshii (N)
- Phacelia ranunculacea (N)
- Phalaris arundinacea (N)
- Phalaris canariensis (I)
- Phalaris caroliniana (N)
- Phaseolus coccineus (I)
- Phaseolus polystachios var. polystachios (N)
- Phaseolus vulgaris (I)
- Phegopteris connectilis (N)
- Phegopteris hexagonoptera (N)
- Phellodendron amurense (I)
- Philadelphus coronarius (I)
- Philadelphus inodorus (N)
- Philadelphus pubescens var. pubescens (N)
- Philadelphus tomentosus (I)
- Phleum pratense (I)
- Phlox divaricata ssp. divaricata (N)
- Phlox glaberrima ssp. triflora (N)
- Phlox latifolia (N)
- Phlox maculata ssp. maculata (N)
- Phlox maculata ssp. pyramidalis (N)
- Phlox paniculata (N)
- Phlox pilosa ssp. pilosa (N)
- Phlox stolonifera (N)
- Phlox subulata ssp. brittonii (N)
- Phlox subulata ssp. subulata (N)
- Phoradendron leucarpum (N)
- Photinia floribunda (N)
- Photinia melanocarpa (N)
- Phragmites australis (N)
- Phryma leptostachya (N)
- Phyla lanceolata (N)
- Phyllanthus caroliniensis ssp. caroliniensis (N)
- Physalis alkekengi (I)
- Physalis grisea (N)
- Physalis heterophylla var. heterophylla (N)
- Physalis hispida (N)
- Physalis longifolia var. longifolia (N)
- Physalis longifolia var. subglabrata (N)
- Physalis philadelphica var. immaculata (I)
- Physalis pubescens var. integrifolia (N)
- Physalis pubescens var. pubescens (N)
- Physalis virginiana var. virginiana (N)
- Physocarpus opulifolius var. intermedius (N)
- Physocarpus opulifolius var. opulifolius (N)
- Physostegia virginiana ssp. praemorsa (N)
- Physostegia virginiana ssp. virginiana (N)
- Phytolacca americana var. americana (N)
- Picea abies (I)
- Picris echioides (I)
- Picris hieracioides (N)
- Picris hieracioides ssp. hieracioides (I)
- Pilea fontana (N)
- Pilea pumila var. pumila (N)
- Pimpinella saxifraga ssp. saxifraga (I)
- Pinellia ternata (I)
- Pinus banksiana (N)
- Pinus echinata (N)
- Pinus nigra (I)
- Pinus rigida (N)
- Pinus strobus (N)
- Pinus sylvestris (I)
- Pinus virginiana (N)
- Piptatherum racemosum (N)
- Piptochaetium avenaceum (N)
- Pistia stratiotes (N)
- Pityopsis graminifolia var. latifolia (N)
- Plantago aristata (N)
- Plantago cordata (N)
- Plantago lanceolata (I)
- Plantago major (I)
- Plantago patagonica (N)
- Plantago psyllium (I)
- Plantago rugelii var. rugelii (N)
- Plantago virginica (N)
- Platanthera × andrewsii (N)
- Platanthera aquilonis (N)
- Platanthera blephariglottis var. blephariglottis (N)
- Platanthera ciliaris (N)
- Platanthera clavellata (N)
- Platanthera flava var. herbiola (N)
- Platanthera grandiflora (N)
- Platanthera hookeri (N)
- Platanthera lacera (N)
- Platanthera leucophaea (N)
- Platanthera orbiculata (N)
- Platanthera peramoena (N)
- Platanthera psycodes (N)
- Platanus occidentalis (N)
- Pleopeltis polypodioides ssp. michauxiana (N)
- Pluchea camphorata (N)
- Poa alsodes (N)
- Poa annua (I)
- Poa arida (N)
- Poa bulbosa (I)
- Poa chapmaniana (N)
- Poa compressa (I)
- Poa cuspidata (N)
- Poa nemoralis (N)
- Poa nemoralis ssp. nemoralis (I)
- Poa paludigena (N)
- Poa palustris (N)
- Poa pratensis (I)
- Poa pratensis ssp. pratensis (N)
- Poa saltuensis (N)
- Poa sylvestris (N)
- Poa trivialis (I)
- Poa wolfii (N)
- Podophyllum peltatum (N)
- Podostemum ceratophyllum (N)
- Pogonia ophioglossoides (N)
- Polanisia dodecandra ssp. dodecandra (N)
- Polanisia dodecandra ssp. trachysperma (N)
- Polanisia jamesii (N)
- Polemonium caeruleum (I)
- Polemonium reptans var. reptans (N)
- Polemonium reptans var. villosum (N)
- Polygala ambigua (N)
- Polygala cruciata var. aquilonia (N)
- Polygala curtissii (N)
- Polygala incarnata (N)
- Polygala paucifolia (N)
- Polygala polygama (N)
- Polygala sanguinea (N)
- Polygala senega (N)
- Polygala verticillata var. isocycla (N)
- Polygala verticillata var. verticillata (N)
- Polygonatum biflorum var. commutatum (N)
- Polygonatum pubescens (N)
- Polygonum achoreum (N)
- Polygonum amphibium var. emersum (N)
- Polygonum amphibium var. stipulaceum (N)
- Polygonum arenastrum (I)
- Polygonum arifolium (N)
- Polygonum aviculare (I)
- Polygonum buxiforme (N)
- Polygonum careyi (N)
- Polygonum cespitosum var. longisetum (I)
- Polygonum cilinode (N)
- Polygonum convolvulus var. convolvulus (I)
- Polygonum cuspidatum (I)
- Polygonum erectum (N)
- Polygonum fowleri ssp. fowleri (N)
- Polygonum hydropiper (I)
- Polygonum hydropiperoides (N)
- Polygonum lapathifolium (N)
- Polygonum orientale (I)
- Polygonum pensylvanicum (N)
- Polygonum perfoliatum (I)
- Polygonum persicaria (I)
- Polygonum punctatum var. confertiflorum (N)
- Polygonum punctatum var. punctatum (N)
- Polygonum ramosissimum var. ramosissimum (N)
- Polygonum robustius (N)
- Polygonum sachalinense (I)
- Polygonum sagittatum (N)
- Polygonum scandens var. cristatum (N)
- Polygonum scandens var. dumetorum (N)
- Polygonum scandens var. scandens (N)
- Polygonum scandens var. dumetorum (I)
- Polygonum setaceum (N)
- Polygonum tenue (N)
- Polygonum virginianum (N)
- Polymnia canadensis (N)
- Polypodium appalachianum (N)
- Polypodium virginianum (N)
- Polystichum acrostichoides var. acrostichoides (N)
- Pontederia cordata (N)
- Populus alba (I)
- Populus balsamifera ssp. balsamifera (N)
- Populus × canadensis (N)
- Populus × canescens (I)
- Populus deltoides ssp. deltoides (N)
- Populus deltoides ssp. monilifera (N)
- Populus grandidentata (N)
- Populus heterophylla (N)
- Populus × jackii (N)
- Populus nigra (I)
- Populus × smithii (N)
- Populus tremuloides (N)
- Portulaca grandiflora (I)
- Portulaca oleracea (I)
- Portulaca oleracea (N)
- Potamogeton amplifolius (N)
- Potamogeton compressus (N)
- Potamogeton crispus (I)
- Potamogeton diversifolius (N)
- Potamogeton epihydrus (N)
- Potamogeton foliosus ssp. foliosus (N)
- Potamogeton friesii (N)
- Potamogeton gramineus (N)
- Potamogeton × hagstroemii (N)
- Potamogeton hillii (N)
- Potamogeton illinoensis (N)
- Potamogeton natans (N)
- Potamogeton nodosus (N)
- Potamogeton perfoliatus (N)
- Potamogeton praelongus (N)
- Potamogeton pulcher (N)
- Potamogeton pusillus ssp. pusillus (N)
- Potamogeton pusillus ssp. tenuissimus (N)
- Potamogeton × rectifolius (N)
- Potamogeton richardsonii (N)
- Potamogeton robbinsii (N)
- Potamogeton spirillus (N)
- Potamogeton strictifolius (N)
- Potamogeton tennesseensis (N)
- Potamogeton vaseyi (N)
- Potentilla argentea var. argentea (I)
- Potentilla arguta ssp. arguta (N)
- Potentilla canadensis var. canadensis (N)
- Potentilla canadensis var. villosissima (N)
- Potentilla inclinata (I)
- Potentilla intermedia (I)
- Potentilla norvegica ssp. monspeliensis (N)
- Potentilla paradoxa (N)
- Potentilla pensylvanica var. pensylvanica (N)
- Potentilla recta (I)
- Potentilla reptans (I)
- Potentilla simplex (N)
- Prenanthes alba (N)
- Prenanthes altissima (N)
- Prenanthes aspera (N)
- Prenanthes crepidinea (N)
- Prenanthes racemosa var. racemosa (N)
- Prenanthes serpentaria (N)
- Prenanthes trifoliolata (N)
- Proboscidea louisianica ssp. louisianica (N)
- Prosartes lanuginosa (N)
- Prosartes maculata (N)
- Proserpinaca palustris var. amblyogona (N)
- Proserpinaca palustris var. crebra (N)
- Prunella laciniata (I)
- Prunella vulgaris ssp. lanceolata (N)
- Prunus americana (N)
- Prunus avium (I)
- Prunus cerasifera (I)
- Prunus cerasus (I)
- Prunus domestica var. domestica (I)
- Prunus hortulana (N)
- Prunus mahaleb (I)
- Prunus mexicana (N)
- Prunus munsoniana (N)
- Prunus nigra (N)
- Prunus pensylvanica var. pensylvanica (N)
- Prunus persica var. persica (I)
- Prunus pumila var. pumila (N)
- Prunus serotina var. serotina (N)
- Prunus subhirtella (I)
- Prunus susquehanae (N) (here considered a synonym of P. pumila)
- Prunus tomentosa (I)
- Prunus virginiana var. virginiana (N)
- Pseudognaphalium macounii (N)
- Pseudognaphalium obtusifolium ssp. obtusifolium (N)
- Pseudolysimachion longifolium (I)
- Ptelea trifoliata ssp. trifoliata var. trifoliata (N)
- Ptelea trifoliata ssp. trifoliata (N)
- Pteridium aquilinum var. latiusculum (N)
- Pteridium aquilinum var. pseudocaudatum (N)
- Puccinellia distans (N)
- Puccinellia distans ssp. distans (I)
- Pueraria montana var. lobata (I)
- Pycnanthemum incanum var. incanum (N)
- Pycnanthemum incanum var. puberulum (N)
- Pycnanthemum muticum (N)
- Pycnanthemum pycnanthemoides var. pycnanthemoides (N)
- Pycnanthemum tenuifolium (N)
- Pycnanthemum verticillatum var. pilosum (N)
- Pycnanthemum verticillatum var. verticillatum (N)
- Pycnanthemum virginianum (N)
- Pyracantha coccinea (I)
- Pyracantha coccinea (N)
- Pyrola americana (N)
- Pyrola asarifolia ssp. asarifolia (N)
- Pyrola chlorantha (N)
- Pyrola elliptica (N)
- Pyrus calleryana (I)
- Pyrus communis (I)
Read more about this topic: Flora Of Ohio