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
— arctic willowherb
Epilobium brachycarpum — panicled willowherb
Epilobium ciliatum — hairy willowherb
Epilobium clavatum — clavate-fruit willowherb
Epilobium coloratum — purpleleaf willowherb
— Dahuria willowherb
Epilobium foliosum — California willowherb
Epilobium glaberrimum — glaucous willowherb
Epilobium halleanum — glandular willowherb
— Hornemann's willowherb
Epilobium lactiflorum — whiteflower willowherb
Epilobium latifolium — river beauty
— slender-fruited willowherb
Epilobium leptophyllum — linear-leaved willowherb

— yellow willowherb
Epilobium minutum — smallflower willowherb
— Olimple Mountain willowherb
Epilobium oregonense — Oregon willowherb
Epilobium palustre — marsh willowherb
— Rocky Mountain willowherb
— downy willowherb
Gaura biennis — biennial gaura
Gaura coccinea — scarlet gaura
Gayophytum diffusum — diffuse groundsmoke
Gayophytum humile — low groundsmoke
— racemed groundsmoke
— 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
— lesser four-point evening-primrose
Oenothera elata — Hooker's evening-primrose
— long-tubed evening-primrose
Oenothera fruticosa — narrowleaf sundrops
— white-stemmed evening-primrose
— Oakes' evening-primrose
— pale evening-primrose
Oenothera parviflora — northern evening-primrose
Oenothera perennis — small sundrops
Oenothera pilosella — meadow evening-primrose
— hairy evening-primrose

Ophioglossaceae[]

— moonwort
Botrychium ascendens — upward-lobed moonwort
Botrychium boreale — northern moonwort
Botrychium campestre — prairie dunewort
Botrychium crenulatum — crenulate moonwort
Botrychium dissectum — cutleaf grapefern
— western moonwort
Botrychium lanceolatum — triangle grapefern
— narrowleaf grapefern
Botrychium lunaria — moonwort grapefern
Botrychium matricariifolium — chamomile grapefern
Botrychium minganense — Mingan's moonwort
Botrychium montanum — mountain moonwort
— little goblin moonwort
Botrychium multifidum — leathery grapefern

Botrychium oneidense — bluntlobe grapefern
— pale moonwort
Botrychium paradoxum — peculiar moonwort
— stalked moonwort
Botrychium pinnatum — northern moonwort
— false daisyleaf grapefern
— rugulose grapefern
Botrychium simplex — least grapefern
— spoonleaf moonwort
Botrychium virginianum — rattlesnake fern
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
— Andrews' lady's-slipper
— Columbian lady's-slipper
— 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
— Aleutian adder's-mouth
Malaxis paludosa — bog adder's-mouth
Malaxis unifolia — green adder's-mouth
Neottia auriculata — auricled twayblade
— southern twayblade
Neottia borealis — northern twayblade
Neottia caurina — western twayblade
Neottia convallarioides — broad-leaved twayblade

Neottia cordata — heartleaf twayblade
— 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
— 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
— 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
— Andrews' platanthera
— Holland's platanthera
— Keenan's platanthera
— Reznicek's platanthera
— Voss' platanthera
Pogonia ophioglossoides — rose pogonia
— 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
— 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[]

Orthotrichum lyellii
— blunt bristle-moss

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