# List of Canadian plants by family O

Main page: List of Canadian plants by family
Families: A | B | C | D | E | F | G | H | I J K | L | M | N | O | P Q | R | S | T | U V W | X Y Z

## 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