List of Canadian plants by family O

Main page: List of Canadian plants by family

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Oedipodiaceae

 * Oedipodium griffithianum

Oleaceae

 * Fraxinus americana — white ash
 * Fraxinus latifolia — Oregon ash
 * Fraxinus nigra — black ash
 * Fraxinus pennsylvanica — green ash
 * Fraxinus profunda — pumpkin ash
 * Fraxinus quadrangulata — blue ash

Onagraceae

 * Boisduvalia densiflora — denseflower spike-primrose
 * Boisduvalia glabella — smooth spike-primrose
 * Calylophus serrulatus — yellow evening-primrose
 * Camissonia andina — Blackfoot River suncup
 * Camissonia breviflora — shortflower suncup
 * Camissonia contorta — dwarf contorted suncup
 * Circaea alpina — small enchanter's-nightshade
 * Circaea lutetiana — southern broadleaf enchanter's-nightshade
 * Circaea x intermedia — intermediate enchanger's-nightshade
 * Clarkia amoena — farewell-to-spring
 * Clarkia pulchella — largeflower clarkia
 * Clarkia purpurea — winecup clarkia
 * Clarkia rhomboidea — tongue clarkia
 * Epilobium anagallidifolium — alpine willowherb
 * Epilobium angustifolium — fireweed
 * Epilobium arcticum — arctic willowherb
 * Epilobium brachycarpum — panicled willowherb
 * Epilobium ciliatum — hairy willowherb
 * Epilobium clavatum — clavate-fruit willowherb
 * Epilobium coloratum — purpleleaf willowherb
 * Epilobium davuricum — Dahuria willowherb
 * Epilobium foliosum — California willowherb
 * Epilobium glaberrimum — glaucous willowherb
 * Epilobium halleanum — glandular willowherb
 * Epilobium hornemannii — Hornemann's willowherb
 * Epilobium lactiflorum — whiteflower willowherb
 * Epilobium latifolium — river beauty
 * Epilobium leptocarpum — slender-fruited willowherb
 * Epilobium leptophyllum — linear-leaved willowherb
 * Epilobium luteum — yellow willowherb
 * Epilobium minutum — smallflower willowherb
 * Epilobium mirabile — Olimple Mountain willowherb
 * Epilobium oregonense — Oregon willowherb
 * Epilobium palustre — marsh willowherb
 * Epilobium saximontanum — Rocky Mountain willowherb
 * Epilobium strictum — downy willowherb
 * Epilobium x wisconsinense
 * Gaura biennis — biennial gaura
 * Gaura coccinea — scarlet gaura
 * Gayophytum diffusum — diffuse groundsmoke
 * Gayophytum humile — low groundsmoke
 * Gayophytum racemosum — racemed groundsmoke
 * Gayophytum ramosissimum — much-branch groundsmoke
 * Ludwigia alternifolia — bushy seedbox
 * Ludwigia palustris — marsh seedbox
 * Ludwigia polycarpa — many-fruit false-loosestrife
 * Oenothera biennis — common evening-primrose
 * Oenothera caespitosa — tufted evening-primrose
 * Oenothera clelandii — lesser four-point evening-primrose
 * Oenothera elata — Hooker's evening-primrose
 * Oenothera flava — long-tubed evening-primrose
 * Oenothera fruticosa — narrowleaf sundrops
 * Oenothera nuttallii — white-stemmed evening-primrose
 * Oenothera oakesiana — Oakes' evening-primrose
 * Oenothera pallida — pale evening-primrose
 * Oenothera parviflora — northern evening-primrose
 * Oenothera perennis — small sundrops
 * Oenothera pilosella — meadow evening-primrose
 * Oenothera villosa — hairy evening-primrose

Ophioglossaceae

 * Botrychium acuminatum — moonwort
 * Botrychium ascendens — upward-lobed moonwort
 * Botrychium boreale — northern moonwort
 * Botrychium campestre — prairie dunewort
 * Botrychium crenulatum — crenulate moonwort
 * Botrychium dissectum — cutleaf grapefern
 * Botrychium hesperium — western moonwort
 * Botrychium lanceolatum — triangle grapefern
 * Botrychium lineare — narrowleaf grapefern
 * Botrychium lunaria — moonwort grapefern
 * Botrychium matricariifolium — chamomile grapefern
 * Botrychium minganense — Mingan's moonwort
 * Botrychium montanum — mountain moonwort
 * Botrychium mormo — little goblin moonwort
 * Botrychium multifidum — leathery grapefern
 * Botrychium oneidense — bluntlobe grapefern
 * Botrychium pallidum — pale moonwort
 * Botrychium paradoxum — peculiar moonwort
 * Botrychium pedunculosum — stalked moonwort
 * Botrychium pinnatum — northern moonwort
 * Botrychium pseudopinnatum — false daisyleaf grapefern
 * Botrychium rugulosum — rugulose grapefern
 * Botrychium simplex — least grapefern
 * Botrychium spathulatum — spoonleaf moonwort
 * Botrychium tunux
 * Botrychium virginianum — rattlesnake fern
 * Botrychium x watertonense
 * Botrychium yaaxudakeit
 * Ophioglossum pusillum — northern adder's-tongue
 * Ophioglossum vulgatum — southern adder's-tongue

Orchidaceae

 * Amerorchis rotundifolia — round-leaved orchis
 * Aplectrum hyemale — puttyroot
 * Arethusa bulbosa — dragon's mouth
 * Calopogon tuberosus — tuberous grass-pink
 * Calypso bulbosa — fairy slipper
 * Cephalanthera austiniae — phantom orchid
 * Coeloglossum viride — longbract green orchis
 * Corallorhiza maculata — spotted coralroot
 * Corallorhiza mertensiana — Merten's coralroot
 * Corallorhiza odontorhiza — autumn coralroot
 * Corallorhiza striata — striped coralroot
 * Corallorhiza trifida — early coralroot
 * Cypripedium acaule — pink lady's-slipper
 * Cypripedium arietinum — ram's-head lady's-slipper
 * Cypripedium candidum — small white lady's-slipper
 * Cypripedium guttatum — spotted lady's-slipper
 * Cypripedium montanum — mountain lady's-slipper
 * Cypripedium parviflorum — American yellow lady's-slipper
 * Cypripedium passerinum — sparrow's-egg lady's-slipper
 * Cypripedium reginae — showy lady's-slipper
 * Cypripedium x andrewsii — Andrews' lady's-slipper
 * Cypripedium x columbianum — Columbian lady's-slipper
 * Cypripedium x favillianum
 * Cypripedium x landonii — Landon's lady's-slipper
 * Dactylorhiza praetermissa — southern marsh orchid
 * Epipactis gigantea — giant helleborine
 * Galearis spectabilis — showy orchis
 * Goodyera oblongifolia — giant rattlesnake-plantain
 * Goodyera pubescens — downy rattlesnake-plantain
 * Goodyera repens — dwarf rattlesnake-plantain
 * Goodyera tesselata — checkered rattlesnake-plantain
 * Isotria medeoloides — small whorled pogonia
 * Isotria verticillata — large whorled pogonia
 * Liparis liliifolia — large twayblade
 * Liparis loeselii — Lösel's twayblade
 * Malaxis brachypoda — white adder's-mouth
 * Malaxis diphyllos — Aleutian adder's-mouth
 * Malaxis paludosa — bog adder's-mouth
 * Malaxis unifolia — green adder's-mouth
 * Neottia auriculata — auricled twayblade
 * Neottia australis — southern twayblade
 * Neottia borealis — northern twayblade
 * Neottia caurina — western twayblade
 * Neottia convallarioides — broad-leaved twayblade
 * Neottia cordata — heartleaf twayblade
 * Neottia x veltmanii — Veltman's twayblade
 * Piperia candida — white piperia
 * Piperia elegans — hillside rein orchid
 * Piperia elongata — denseflower rein orchid
 * Piperia transversa — royal rein orchid
 * Piperia unalascensis — Alaska rein orchid
 * Platanthera albida — vanilla-scent bog orchid
 * Platanthera aquilonis
 * Platanthera blephariglottis — white-fringe orchis
 * Platanthera chorisiana — Choriso bog orchid
 * Platanthera clavellata — small green woodland orchid
 * Platanthera dilatata — leafy white orchis
 * Platanthera flava — southern rein orchid
 * Platanthera grandiflora — large purple-fringe orchis
 * Platanthera hookeri — Hooker's orchis
 * Platanthera hyperborea — leafy northern green orchid
 * Platanthera lacera — green-fringe orchis
 * Platanthera leucophaea — eastern prairie white-fringed orchid
 * Platanthera leucostachys — Bog rein orchid,  scentbottle
 * Platanthera obtusata — small northern bog orchid
 * Platanthera orbiculata — large roundleaf orchid
 * Platanthera praeclara — western prairie white-fringed orchid
 * Platanthera psycodes — small purple-fringe orchis
 * Platanthera stricta — slender bog orchid
 * Platanthera x andrewsii — Andrews' platanthera
 * Platanthera x hollandiae — Holland's platanthera
 * Platanthera x keenanii — Keenan's platanthera
 * Platanthera x media
 * Platanthera x reznicekii — Reznicek's platanthera
 * Platanthera x vossii — Voss' platanthera
 * Pogonia ophioglossoides — rose pogonia
 * Spiranthes casei — Case's ladies'-tresses
 * Spiranthes cernua — nodding ladies'-tresses
 * Spiranthes lacera — southern slender ladies'-tresses
 * Spiranthes lucida — shining ladies'-tresses
 * Spiranthes magnicamporum — Great Plains ladies'-tresses
 * Spiranthes ochroleuca — yellow nodding ladies'-tresses
 * Spiranthes ovalis — lesser ladies'-tresses
 * Spiranthes romanzoffiana — hooded ladies'-tresses
 * Spiranthes x intermedia
 * Spiranthes x simpsonii — Simpson's ladies'-tresses
 * Triphora trianthophora — nodding pogonia

Orobanchaceae

 * Boschniakia hookeri — Vancouver groundcone
 * Boschniakia rossica — northern groundcone
 * Boschniakia strobilacea — California groundcone
 * Conopholis americana — American cancer-root
 * Epifagus virginiana — beechdrops
 * Orobanche californica — California broomrape
 * Orobanche corymbosa — flat-top broomrape
 * Orobanche fasciculata — clustered broomrape
 * Orobanche ludoviciana — Louisiana broomrape
 * Orobanche pinorum — pine broomrape
 * Orobanche uniflora — one-flowered broomrape

Orthotrichaceae

 * Amphidium californicum
 * Amphidium lapponicum
 * Amphidium mougeotii
 * Drummondia prorepens
 * Orthotrichum affine
 * Orthotrichum alpestre
 * Orthotrichum anomalum
 * Orthotrichum consimile
 * Orthotrichum cupulatum
 * Orthotrichum gymnostomum
 * Orthotrichum hallii
 * Orthotrichum laevigatum
 * Orthotrichum lyellii
 * Orthotrichum obtusifolium — blunt bristle-moss
 * Orthotrichum ohioense
 * Orthotrichum pallens
 * Orthotrichum pellucidum
 * Orthotrichum pulchellum
 * Orthotrichum pumilum
 * Orthotrichum pusillum
 * Orthotrichum pylaisii
 * Orthotrichum rivulare
 * Orthotrichum rupestre
 * Orthotrichum sordidum
 * Orthotrichum speciosum
 * Orthotrichum stellatum
 * Orthotrichum stramineum
 * Orthotrichum strangulatum
 * Orthotrichum striatum
 * Orthotrichum tenellum
 * Ulota coarctata
 * Ulota crispa
 * Ulota curvifolia
 * Ulota drummondii
 * Ulota hutchinsiae
 * Ulota megalospora
 * Ulota obtusiuscula
 * Ulota phyllantha
 * Zygodon conoideus
 * Zygodon gracilis
 * Zygodon reinwardtii
 * Zygodon viridissimus

Osmundaceae

 * Osmunda claytoniana — interrupted fern
 * Osmunda spectabilis — royal fern
 * Osmundastrum cinnamomeum — cinnamon fern

Oxalidaceae

 * Oxalis dillenii — Dillen's woodsorrel
 * Oxalis montana — white woodsorrel
 * Oxalis oregana — Oregon woodsorrel
 * Oxalis stricta — common yellow woodsorrel
 * Oxalis suksdorfii — western yellow oxalis