| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| PIVE2 | Pilophorus vegae Krog | nail lichen | Stereocaulaceae
|
| PILOP2 | Pilophorus Th. Fr. | nail lichen | Stereocaulaceae
|
| PINO2 | Pilosella novae-angliae Rydb. | Braya humilis | Brassicaceae
|
| PIRI7 | Pilosella richardsonii Rydb. | Braya humilis | Brassicaceae
|
| PINO | Pilosocereus nobilis (Haw.) Byles & Rowley | Pilosocereus royenii | Cactaceae
|
| PIROD | Pilosocereus robinii (Lem.) Byles & Rowley var. deeringii (Small) Kartesz & Gandhi | Deering's tree cactus | Cactaceae
|
| PIROR2 | Pilosocereus robinii (Lem.) Byles & Rowley var. robinii | Key tree cactus | Cactaceae
|
| PIRO5 | Pilosocereus robinii (Lem.) Byles & Rowley | Key tree cactus | Cactaceae
|
| PIRO6 | Pilosocereus royenii (L.) Byles & Rowley | Royen's tree cactus | Cactaceae
|
| PILOS2 | Pilosocereus Byles & Rowley | tree cactus | Cactaceae
|
| PITH | Pilostyles thurberi Gray | Thurber's stemsucker | Rafflesiaceae
|
| PILOS | Pilostyles Guill. | stemsucker | Rafflesiaceae
|
| PIAM | Pilularia americana A. Braun | American pillwort | Marsileaceae
|
| PILUL | Pilularia L. | pillwort | Marsileaceae
|
| PIAC5 | Pimenta acris (Sw.) Kostel. | Pimenta racemosa | Myrtaceae
|
| PIDI2 | Pimenta dioica (L.) Merr. | allspice | Myrtaceae
|
| PIOF | Pimenta officinalis Lindley | Pimenta dioica | Myrtaceae
|
| PIPI5 | Pimenta pimenta (L.) Karst. | Pimenta dioica | Myrtaceae
|
| PIRAG | Pimenta racemosa (P. Mill.) J.W. Moore var. grisea (Kiaersk.) Fosberg | bayrumtree | Myrtaceae
|
| PIRAR | Pimenta racemosa (P. Mill.) J.W. Moore var. racemosa | bayrumtree | Myrtaceae
|
| PIRA | Pimenta racemosa (P. Mill.) J.W. Moore | bayrumtree | Myrtaceae
|
| PIMEN | Pimenta Lindl. | pimenta | Myrtaceae
|
| PIAN3 | Pimpinella anisum L. | anise burnet saxifrage | Apiaceae
|
| PIMA9 | Pimpinella magna L. | Pimpinella major | Apiaceae
|
| PIMA6 | Pimpinella major (L.) Huds. | hollowstem burnet saxifrage | Apiaceae
|
| PISAN | Pimpinella saxifraga L. ssp. nigra (P. Mill.) Gaudin | solidstem burnet saxifrage | Apiaceae
|
| PISAS | Pimpinella saxifraga L. ssp. saxifraga | solidstem burnet saxifrage | Apiaceae
|
| PISAM2 | Pimpinella saxifraga L. var. major L. | Pimpinella major | Apiaceae
|
| PISA | Pimpinella saxifraga L. | solidstem burnet saxifrage | Apiaceae
|
| PIMPI | Pimpinella L. | burnet saxifrage | Apiaceae
|
| PIIN5 | Pinanga insignis Becc. | | Arecaceae
|
| PINAN | Pinanga Blume | | Arecaceae
|
| PIPA | Pinaropappus parvus Blake | small rocklettuce | Asteraceae
|
| PIROF | Pinaropappus roseus (Less.) Less. var. foliosus (Heller) Shinners | white rocklettuce | Asteraceae
|
| PIROR | Pinaropappus roseus (Less.) Less. var. roseus | white rocklettuce | Asteraceae
|
| PIRO | Pinaropappus roseus (Less.) Less. | white rocklettuce | Asteraceae
|
| PINAR | Pinaropappus Less. | rocklettuce | Asteraceae
|
| PIBR6 | Pinckneya bracteata (Bartr.) Raf. | fevertree | Rubiaceae
|
| PIPU3 | Pinckneya pubens Michx. | Pinckneya bracteata | Rubiaceae
|
| PINCK | Pinckneya Michx. | pinckneya | Rubiaceae
|
| PITE | Pinellia ternata (Thunb.) Makino ex Breitenbach | crowdipper | Araceae
|
| PINEL | Pinellia Ten. | pinellia | Araceae
|
| PICA7 | Pinguicula caerulea Walt. | blueflower butterwort | Lentibulariaceae
|
| PIIO | Pinguicula ionantha Godfrey | violet butterwort | Lentibulariaceae
|
| PILU2 | Pinguicula lutea Walt. | yellow butterwort | Lentibulariaceae
|
| PIMAM2 | Pinguicula macroceras Link var. macroceras | California butterwort | Lentibulariaceae
|
| PIMAM3 | Pinguicula macroceras Link var. microceras (Cham.) Casper | California butterwort | Lentibulariaceae
|
| PIMA7 | Pinguicula macroceras Link | California butterwort | Lentibulariaceae
|
| PIPL | Pinguicula planifolia Chapman | Chapman's butterwort | Lentibulariaceae
|
| PIPR | Pinguicula primuliflora Wood & Godfrey | southern butterwort | Lentibulariaceae
|
| PIPUB | Pinguicula pumila Michx. var. buswellii Moldenke | Pinguicula pumila | Lentibulariaceae
|
| PIPU4 | Pinguicula pumila Michx. | small butterwort | Lentibulariaceae
|
| PIVI | Pinguicula villosa L. | hairy butterwort | Lentibulariaceae
|
| PIVUM | Pinguicula vulgaris L. ssp. macroceras (Link) Calder & Taylor | Pinguicula macroceras var. macroceras | Lentibulariaceae
|
| PIVUA | Pinguicula vulgaris L. var. americana Gray | Pinguicula vulgaris | Lentibulariaceae
|
| PIVUM2 | Pinguicula vulgaris L. var. macroceras (Link) Herder | Pinguicula macroceras var. macroceras | Lentibulariaceae
|
| PIVU | Pinguicula vulgaris L. | common butterwort | Lentibulariaceae
|
| PINGU | Pinguicula L. | butterwort | Lentibulariaceae
|
| PIAL | Pinus albicaulis Engelm. | whitebark pine | Pinaceae
|
| PIAP | Pinus apacheca Lemmon | Pinus engelmannii | Pinaceae
|
| PIARL | Pinus aristata Engelm. var. longaeva (D.K. Bailey) Little | Pinus longaeva | Pinaceae
|
| PIAR | Pinus aristata Engelm. | bristlecone pine | Pinaceae
|
| PIARA | Pinus arizonica Engelm. var. arizonica | Arizona pine | Pinaceae
|
| PIARS2 | Pinus arizonica Engelm. var. stormiae Martinez | Arizona pine | Pinaceae
|
| PIAR5 | Pinus arizonica Engelm. | Arizona pine | Pinaceae
|
| PIAT | Pinus attenuata Lemmon | knobcone pine | Pinaceae
|
| PIAT2 | Pinus �attenuradiata Stockwell & Righter | | Pinaceae
|
| PIAU3 | Pinus australis Michx. f. | Pinus palustris | Pinaceae
|
| PIAY | Pinus ayacahuite C.A. Ehrenb. | Pinus strobiformis | Pinaceae
|
| PIBAA | Pinus balfouriana Grev. & Balf. ssp. austrina R.J. & J.D. Mastrogiuseppe | foxtail pine | Pinaceae
|
| PIBAB | Pinus balfouriana Grev. & Balf. ssp. balfouriana | foxtail pine | Pinaceae
|
| PIBA | Pinus balfouriana Grev. & Balf. | foxtail pine | Pinaceae
|
| PIBA3 | Pinus balsamea L. | Abies balsamea | Pinaceae
|
| PIBA2 | Pinus banksiana Lamb. | jack pine | Pinaceae
|
| PIBE | Pinus beardsleyi A. Murr. | Pinus ponderosa var. ponderosa | Pinaceae
|
| PIBE2 | Pinus benthamiana Hartw. | Pinus ponderosa var. ponderosa | Pinaceae
|
| PIBR7 | Pinus brachyptera Engelm. | Pinus ponderosa var. ponderosa | Pinaceae
|
| PIBR9 | Pinus brutia Tenore | pine | Pinaceae
|
| PICA16 | Pinus californiarum D.K. Bailey | California pine | Pinaceae
|
| PICA15 | Pinus canariensis C. Smith | Canary Island pine | Pinaceae
|
| PICA2 | Pinus caribaea sensu Small, non Morelet | Pinus elliottii var. elliottii | Pinaceae
|
| PICE2 | Pinus cembra L. | Swiss stone pine | Pinaceae
|
| PICEB | Pinus cembroides Zucc. var. bicolor Little | Pinus discolor | Pinaceae
|
| PICEE | Pinus cembroides Zucc. var. edulis (Engelm.) Voss | Pinus edulis | Pinaceae
|
| PICER | Pinus cembroides Zucc. var. remota Little | Pinus remota | Pinaceae
|
| PICE | Pinus cembroides Zucc. | Mexican pinyon | Pinaceae
|
| PICH3 | Pinus chihuahuana Engelm. | Pinus leiophylla var. chihuahuana | Pinaceae
|
| PICLI | Pinus clausa (Chapman ex Engelm.) Vasey ex Sarg. ssp. immuginata (Ward) E. Murr. | Pinus clausa | Pinaceae
|
| PICLI2 | Pinus clausa (Chapman ex Engelm.) Vasey ex Sarg. var. immuginata Ward | Pinus clausa | Pinaceae
|
| PICL | Pinus clausa (Chapman ex Engelm.) Vasey ex Sarg. | sand pine | Pinaceae
|
| PICOB2 | Pinus contorta Dougl. ex Loud. ssp. bolanderi (Parl.) Critchfield | Pinus contorta var. bolanderi | Pinaceae
|
| PICOL2 | Pinus contorta Dougl. ex Loud. ssp. latifolia (Engelm. ex S. Wats.) Critchfield | Pinus contorta var. latifolia | Pinaceae
|
| PICOM4 | Pinus contorta Dougl. ex Loud. ssp. murrayana (Grev. & Balf.) Critchfield | Pinus contorta var. murrayana | Pinaceae
|
| PICOB | Pinus contorta Dougl. ex Loud. var. bolanderi (Parl.) Vasey | Bolander beach pine | Pinaceae
|
| PICOC | Pinus contorta Dougl. ex Loud. var. contorta | lodgepole pine | Pinaceae
|
| PICOL | Pinus contorta Dougl. ex Loud. var. latifolia Engelm. ex S. Wats. | tall lodgepole pine | Pinaceae
|
| PICOM | Pinus contorta Dougl. ex Loud. var. murrayana (Grev. & Balf.) Engelm. | Murray lodgepole pine | Pinaceae
|
| PICO | Pinus contorta Dougl. ex Loud. | lodgepole pine | Pinaceae
|
| PICO3 | Pinus coulteri D. Don | Coulter pine | Pinaceae
|
| PICUD | Pinus culminicola Andr. & Beam. var. discolor (D.K. Bailey & Hawksworth) Silba | Pinus discolor | Pinaceae
|
| PIDE3 | Pinus densa (Little & Dorman) Gaussen | Pinus elliottii var. densa | Pinaceae
|