- Oberonia setigera
- Octomeria gracilis
- Odontioda Atahualpa
- Odontioda Durham Dawn x Odontioda Picasso "Or257 Red Dawn Pearl Pierce"
- Odontioda George McMahon 'Fortuna'
- Odontioda Lovely Morning Sayaka 'Very Dark'
- Odontioda Nationhood Bossa Nova
- Odontioda Nichirei Sunrise x Odontoglossum crispum
- Odontioda Quedlinburg
- Odontioda Stirbic
- Odontioda Taylor Barfield 'This and That'
- Odontocidium Christopher Merino
- Odontocidium Hansueli Isler
- Odontocidium Mayfair 'RCW'
- Odontocidium Yellow Tiger
- Odontoglossum bictoniense x Odontioda Teipel´s Panda
- Odontoglossum blandum
- Odontoglossum cirrhosum
- Odontoglossum crispum
- Odontoglossum Cynthia Hill
- Odontoglossum Geyser Gold 'Okika'
- Odontoglossum gloriosum
- Odontoglossum Hans Koch x Odontocidium Tiger Crow 'Golden Gate'
- Odontoglossum harryanum
- Odontoglossum Holm Lighthouse
- Odontoglossum kegeljani
- Odontoglossum Margarete Holm
- Odontoglossum naevium
- Odontoglossum naevium x andreettae
- Odontoglossum praestans
- Odontoglossum Rawdon Jester × splendens
- Odontoglossum sceptrum
- Odontoglossum tenue
- Odontoglossum trilobum x Odontocidium Tiger Glow
- Odontoglossum wyattianum
- Odontonia Boussole 'Blanche'
- Odontonia Memoria Martin Orenstein 'Lulu'
- Odontonia Papageno 'Lavender Lady'
- Odontonia Papageno 'Mi Amour'
- Oeceoclades gracillima
- Oeceoclades maculata
- Oeceoclades peyrotii sp.nov.
- Oeceoclades rauhii
- Oeceoclades roseovariegata
- Oeceoclades spathulifera
- Oeonia oncidiiflora (rosea)
- Oeoniella polystachys
- Oerstedella centradenia
- Oerstedella pseudoschumanniana
- Oerstedella wallisii
-
Omoea philippinensis
- Oncidium Aidita Tosi
- Oncidium alexandrae
- Oncidium Aloha Iwanaka
- Oncidium ascendens
- Oncidium beyrodtioides
- Oncidium brachyandrum
- Oncidium cebolleta
- Oncidium cheirophorum
- Oncidium cirrhosum
- Oncidium coloratum
- Oncidium forbesii
- Oncidium Golden Anniversary 'Hildos'
- Oncidium Gower Ramsey 'Lemon Heart'
- Oncidium graminifolium
- Oncidium hintonii
- Oncidium Jiuhbao Gold 'Tainan'
- Oncidium Josephine 'fragrance'
- Oncidium Josephine x lanceanum
- Oncidium Kalihi
- Oncidium Kalihi x (papilio x sanderae)
- Oncidium kramerianum
- Oncidium lanceanum
- Oncidium lanceanum x kramerianum
- Oncidium limminghei
- Oncidium lindenii
- Oncidium luridum
- Oncidium macranthum
- Oncidium Namboh Waltz 'Boso Sweet'
- Oncidium nanum
- Oncidium nobile
- Oncidium noezlianum
- Oncidium (paphilio x kalihi) 'Green Valley'
- Oncidium Papilio
- Oncidium papilio
- Oncidium phymatochillum
- Oncidium Pink Deluxe Maroon Delight
- Oncidium Pink Panser
- Oncidium pumilum
- Oncidium Red Mini 'CT Little Cherry'
- Oncidium Ron's Rippling Delight 'Pacific Parfait'
- Oncidium roseum
- Oncidium sanderae
- Oncidium sarcodes
- Oncidium splendidum
- Oncidium stacyi
- Oncidium stramineum
- Oncidium strictum
- Oncidium Sweet Sugar 'Emperor'
- Oncidium Sweet Sugar 'Yellow King'
- Oncidium (Tolumnea) Jairak Rainbow orange
- Oncidium (Tolumnea) Jairak Rainbow Orange Spot
- Oncidium (Tolumnea) Jairak Rainbow Pink Spot
- Oncidium (Tolumnea) Jairak Rainbow yellow Red Spot
- Oncidium (Tolumnea) Linda Shangrilla x Golden Sunset
-
Oncidium (Tolumnia) hybrids
- Oncidium (Tolumnia) Jairak 'Maroon Spot'
- Oncidium (Tolumnia) Jairak Firm 'Big Bang'
- Oncidium (Tolumnia) Jairak Firm 'Black Bull'
- Oncidium (Tolumnia) Jairak Firm 'Brown Oak'
- Oncidium (Tolumnia) Jairak Firm 'Gules'
- Oncidium (Tolumnia) Jairak Firm 'Mocha Spot'
- Oncidium (Tolumnia) Jairak Firm 'Red Mask'
- Oncidium (Tolumnia) Jairak Firm 'Red Spread'
- Oncidium (Tolumnia) Jairak Firm 'Super Brown'
- Oncidium (Tolumnia) Jairak Firm 'Super Red'
- Oncidium (Tolumnia) Jairak Rainbow brown
- Oncidium (Tolumnia) Jairak Rainbow yellow
- Oncidium (Tolumnia) Midas
- Oncidium (Tolumnia) Moriyama Beauty 'Pinky Circle'
- Oncidium (Tolumnia) Moriyama Beauty 'Sweet Dot'
- Oncidium (Tolumnia) Moriyama Invention 'Mars'
- Oncidium (Tolumnia) Moriyama Invention 'Red Sun'
- Oncidium (Tolumnia) Moriyama Starbright 'Red Star'
- Oncidium (Tolumnia) Moriyama Starbright 'Yolk'
- Oncidium (Tolumnia) Popoki Red
- Oncidium (Tolumnia) Red Spot Maliwan
- Oncidium Tsiku Marguerite 'Chian-Tzy Dragon #1'
- Oncidium Tsiku Marguerite 'Romantic Fantasy'
- Oncidium Twinkle
- Oncidium Twinkle 'Chian-Tzy Delight'
- Oncidium Twinkle 'Chian-Tzy Golden'
- Oncidium Twinkle 'CT Delight'
- Oncidium Twinkle 'CT Flamingo'
- Oncidium Twinkle 'CT Golden Fragrance'
- Oncidium Twinkle 'CT White Strong'
- Oncidium Twinkle 'CT-Red Fantasy'
- Oncidium Twinkle 'Fragrance Fantasy'
- Oncidium Twinkle 'Golden #3'
- Oncidium Twinkle 'Red Fantasy'
- Oncidium (Twinkle x ornithohynchum) 'CT Romantic Fantasy'
- Oncidium varicosum
- Oncidium vulcanicum
- Oncidium Wendy’s Valentine 'OC 200'
- Oncidium zappii x Comparettia speciosa
- Ornithidium ruberrimum
- Ornithocephalus cochleariformis
- Ornithocephalus gladiatus
- Ornithocephalus inflexus
- Ornithocephalus suarezii
- Osmoglossum egertonii
- Osmoglossum pulchellum
- Otoglossum coronarium