| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| OPVU4 | Opegrapha vulgata Ach. | scribble lichen | Opegraphaceae
|
| OPEGR | Opegrapha Ach. | scribble lichen | Opegraphaceae
|
| OPDI4 | Operculina dissecta (Jacq.) House | Merremia dissecta | Convolvulaceae
|
| OPPI | Operculina pinnatifida (Kunth) O'Donell | tansyleaf lidpod | Convolvulaceae
|
| OPTR2 | Operculina triquetra (Vahl) Hallier f. | Operculina turpethum var. turpethum | Convolvulaceae
|
| OPTU6 | Operculina tuberosa (L.) Meisn. | Merremia tuberosa | Convolvulaceae
|
| OPTUT2 | Operculina turpethum (L.) Silva Manso var. turpethum | St. Thomas lidpod | Convolvulaceae
|
| OPTUV | Operculina turpethum (L.) Silva Manso var. ventricosa (Bertero) Austin & Staples | St. Thomas lidpod | Convolvulaceae
|
| OPTU8 | Operculina turpethum (L.) Silva Manso | St. Thomas lidpod | Convolvulaceae
|
| OPVE2 | Operculina ventricosa (Bertero) Peter | Operculina turpethum var. ventricosa | Convolvulaceae
|
| OPERC | Operculina Silva Manso | lidpod | Convolvulaceae
|
| OPPU6 | Opgraphoidea pulvinata (Rehm) Fink | Opegrapha pulvinata | Opegraphaceae
|
| OPQU2 | Opgraphoidea quaternella (Nyl.) FInk | Opegrapha quaternella | Opegraphaceae
|
| OPST7 | Opgraphoidea staurothelicola Fink | Opegrapha staurothelicola | Opegraphaceae
|
| OPCA8 | Ophioglossum californicum Prantl | California adderstongue | Ophioglossaceae
|
| OPCO | Ophioglossum concinnum Brack. | tropical adderstongue | Ophioglossaceae
|
| OPCRC | Ophioglossum crotalophoroides Walt. var. crotalophoroides | bulbous adderstongue | Ophioglossaceae
|
| OPCRN | Ophioglossum crotalophoroides Walt. var. nanum Osten ex De Lichtenstein | bulbous adderstongue | Ophioglossaceae
|
| OPCR | Ophioglossum crotalophoroides Walt. | bulbous adderstongue | Ophioglossaceae
|
| OPDE3 | Ophioglossum dendroneuron E. St. John | Ophioglossum nudicaule | Ophioglossaceae
|
| OPEL2 | Ophioglossum ellipticum Hook. & Grev. | Ophioglossum nudicaule | Ophioglossaceae
|
| OPEN | Ophioglossum engelmannii Prantl | limestone adderstongue | Ophioglossaceae
|
| OPLUC | Ophioglossum lusitanicum L. ssp. californicum (Prantl) R.T. Clausen | Ophioglossum californicum | Ophioglossaceae
|
| OPLUC2 | Ophioglossum lusitanicum L. var. californicum (Prantl) Broun | Ophioglossum californicum | Ophioglossaceae
|
| OPMO4 | Ophioglossum mononeuron E. St. John | Ophioglossum nudicaule | Ophioglossaceae
|
| OPNUM | Ophioglossum nudicaule L. f. var. minus Clausen | Ophioglossum nudicaule | Ophioglossaceae
|
| OPNUT | Ophioglossum nudicaule L. f. var. tenerum (Mett. ex Prantl) Clausen | Ophioglossum nudicaule | Ophioglossaceae
|
| OPNU | Ophioglossum nudicaule L. f. | least adderstongue | Ophioglossaceae
|
| OPPA3 | Ophioglossum palmatum L. | Cheiroglossa palmata | Ophioglossaceae
|
| OPPEF | Ophioglossum pendulum L. ssp. falcatum (K. Presl) Clausen | Old World adderstongue | Ophioglossaceae
|
| OPPEP | Ophioglossum pendulum L. ssp. pendulum | Old World adderstongue | Ophioglossaceae
|
| OPPE | Ophioglossum pendulum L. | Old World adderstongue | Ophioglossaceae
|
| OPPE2 | Ophioglossum petiolatum Hook. | longstem adderstongue | Ophioglossaceae
|
| OPPU3 | Ophioglossum pusillum Raf. | northern adderstongue | Ophioglossaceae
|
| OPPY3 | Ophioglossum pycnostichum (Fern.) A.& D. L�ve | Ophioglossum vulgatum | Ophioglossaceae
|
| OPRE | Ophioglossum reticulatum L. | netted adderstongue | Ophioglossaceae
|
| OPTE5 | Ophioglossum tenerum Mett. ex Prantl | Ophioglossum nudicaule | Ophioglossaceae
|
| OPVUA | Ophioglossum vulgatum L. var. alaskanum (E.G. Britt.) C. Christens. | Ophioglossum pusillum | Ophioglossaceae
|
| OPVUP | Ophioglossum vulgatum L. var. pseudopodum (Blake) Farw. | Ophioglossum pusillum | Ophioglossaceae
|
| OPVUP2 | Ophioglossum vulgatum L. var. pycnostichum Fern. | Ophioglossum vulgatum | Ophioglossaceae
|
| OPVU | Ophioglossum vulgatum L. | southern adderstongue | Ophioglossaceae
|
| OPVU3 | Ophioglossum vulgatum auct. non L. | Ophioglossum pusillum | Ophioglossaceae
|
| OPHIO | Ophioglossum L. | adderstongue | Ophioglossaceae
|
| OPHE4 | Ophioparma herreri (Zahlbr.) Kalb & Staiger | Ophioparma rubricosa | Ophioparmaceae
|
| OPLA4 | Ophioparma lapponica (Rasanen) Hafellner & R. W. Rogers | | Ophioparmaceae
|
| OPRU9 | Ophioparma rubricosa (Mull. Arg.) S. Ekman | | Ophioparmaceae
|
| OPHIO2 | Ophioparma Norman | ophioparma | Ophioparmaceae
|
| OPJA3 | Ophiopogon jaburan (Sieb.) Lodd. | lilyturf | Liliaceae
|
| OPJA | Ophiopogon japonicus (L. f.) Ker Gawler | dwarf lilyturf | Liliaceae
|
| OPHIO3 | Ophiopogon Ker-Gawl. | ophiopogon | Liliaceae
|
| OPAU5 | Ophrys auriculata (Wieg.) House | Listera auriculata | Orchidaceae
|
| OPAU6 | Ophrys australis (Lindl.) House | Listera australis | Orchidaceae
|
| OPCA4 | Ophrys caurina (Piper) Rydb. | Listera caurina | Orchidaceae
|
| OPCO8 | Ophrys convallarioides (Sw.) W. Wight | Listera convallarioides | Orchidaceae
|
| OPCO9 | Ophrys cordata L. | Listera cordata var. cordata | Orchidaceae
|
| OPIN2 | Ophrys insectifera L. | fly orchid | Orchidaceae
|
| OPSM | Ophrys smallii (Wieg.) House | Listera smallii | Orchidaceae
|
| OPHRY | Ophrys L. | ophrys | Orchidaceae
|
| OPST4 | Opizia stolonifera J. Presl | Acapulco grass | Poaceae
|
| OPIZI | Opizia J. Presl | opizia | Poaceae
|
| OPBU | Oplismenus burmanni auct. non (Retz.) Beauv. | Oplismenus hirtellus | Poaceae
|
| OPCOS2 | Oplismenus compositus (L.) Beauv. var. setarius (Lam.) F.M. Bailey | Oplismenus hirtellus | Poaceae
|
| OPCO2 | Oplismenus compositus (L.) Beauv. | running mountaingrass | Poaceae
|
| OPCR2 | Oplismenus crus-pavonis Kunth | Echinochloa crus-pavonis var. crus-pavonis | Poaceae
|
| OPHIS | Oplismenus hirtellus (L.) Beauv. ssp. setarius (Lam.) Mez ex Ekman | Oplismenus hirtellus | Poaceae
|
| OPHI | Oplismenus hirtellus (L.) Beauv. | bristle basketgrass | Poaceae
|
| OPPO4 | Oplismenus polystachyus Kunth | Echinochloa polystachya | Poaceae
|
| OPSE | Oplismenus setarius (Lam.) Roemer & J.A. Schultes | Oplismenus hirtellus | Poaceae
|
| OPTE4 | Oplismenus tenuis J. Presl | Ichnanthus tenuis | Poaceae
|
| OPUN | Oplismenus undulatifolius (Ard.) Beauv. | wavyleaf basketgrass | Poaceae
|
| OPLIS | Oplismenus Beauv. | basketgrass | Poaceae
|
| OPMI | Oplonia microphylla (Lam.) Stearn | thicketwort | Acanthaceae
|
| OPSP4 | Oplonia spinosa (Jacq.) Raf. | pricklybush | Acanthaceae
|
| OPLON | Oplonia Raf. | oplonia | Acanthaceae
|
| OPHO | Oplopanax horridus Miq. | devilsclub | Araliaceae
|
| OPLOP | Oplopanax (Torr. & Gray) Miq. | oplopanax | Araliaceae
|
| OPGR4 | Oplotheca gracilis Hook. | Froelichia gracilis | Amaranthaceae
|
| OPAL | Opulaster alabamensis Rydb. | Physocarpus opulifolius var. opulifolius | Rosaceae
|
| OPAU4 | Opulaster australis Rydb. | Physocarpus opulifolius var. opulifolius | Rosaceae
|
| OPIN | Opulaster intermedius Rydb. | Physocarpus opulifolius var. intermedius | Rosaceae
|
| OPOP2 | Opulaster opulifolius (L.) Kuntze | Physocarpus opulifolius var. opulifolius | Rosaceae
|
| OPST5 | Opulaster stellatus Rydb. | Physocarpus opulifolius var. opulifolius | Rosaceae
|
| OPAB | Opuntia abjecta Small | Opuntia triacantha | Cactaceae
|
| OPACG2 | Opuntia acanthocarpa Engelm. & Bigelow ssp. ganderi C.B. Wolf | Opuntia ganderi | Cactaceae
|
| OPACA | Opuntia acanthocarpa Engelm. & Bigelow var. acanthocarpa | buckhorn cholla | Cactaceae
|
| OPACC | Opuntia acanthocarpa Engelm. & Bigelow var. coloradensis L. Benson | Colorado buckhorn cholla | Cactaceae
|
| OPACG | Opuntia acanthocarpa Engelm. & Bigelow var. ganderi (C.B. Wolf) L. Benson | Opuntia ganderi | Cactaceae
|
| OPACM | Opuntia acanthocarpa Engelm. & Bigelow var. major (Engelm. & Bigelow) L. Benson | buckhorn cholla | Cactaceae
|
| OPACT | Opuntia acanthocarpa Engelm. & Bigelow var. thornberi (Thornb. & Bonker) L. Benson | Thornber's buckhorn cholla | Cactaceae
|
| OPAC | Opuntia acanthocarpa Engelm. & Bigelow | buckhorn cholla | Cactaceae
|
| OPAG | Opuntia aggeria B.E. Ralston & Hilsenbeck | Big Bend pricklypear | Cactaceae
|
| OPAM | Opuntia ammophila Small | Opuntia humifusa var. ammophila | Cactaceae
|
| OPAN | Opuntia antillana Britt. & Rose | Opuntia cubensis | Cactaceae
|
| OPAR5 | Opuntia arborescens Engelm. | Opuntia imbricata var. imbricata | Cactaceae
|
| OPAR2 | Opuntia arbuscula Engelm. | Arizona pencil cholla | Cactaceae
|
| OPAR3 | Opuntia arenaria Engelm. | El Paso pricklypear | Cactaceae
|
| OPAR4 | Opuntia arizonica Griffiths | Opuntia phaeacantha var. major | Cactaceae
|
| OPAT | Opuntia atrispina Griffiths | border pricklypear | Cactaceae
|
| OPAT2 | Opuntia atrocapensis Small | Opuntia stricta var. dillenii | Cactaceae
|
| OPAU10 | Opuntia aurantiaca Lindl. | tiger-pear | Cactaceae
|
| OPAU2 | Opuntia aurea E.M. Baxter | golden pricklypear | Cactaceae
|