Orbea umbracula Oreocereus celsianus
Origanum x 'Kents Beauty' Origanum dictamnus
Origanum dictamnus 'Amargcus Dictamnus' Origanum laevigatum 'Herrenhausen'
Origanum laevigatum 'Rosenkuppel' Origanum majorana 'Compactum'
Origanum majorana 'Sicillian' Origanum pulchellum
Origanum rotundifolium Origanum syriacum
Origanum vulgare Origanum vulgare 'Aureum'
Origanum vulgare 'Thumbles' Origanum vulgare 'Variegatum'
Origanum vulgare ssp. hirtum 'Noa' Ornithogalum dubium 'Orange Cream'
Ornithogalum oligophyllum Ornithogalum umbellatum
Orontium aquaticum Orostachys iwarenge
Oryza sativa 'Black Madras' Osmunda cinnamonea
Osmunda claytonia Osmunda regalis
Osmunda regalis 'Purpurescens' Osmunda regalis var. spectabilis
Osteospermum 'Brightside' Osteospermum 'Flower Power Pink'
Osteospermum 'Impassion White' Osteospermum 'Passion Mix'
Osteospermum 'Pinwheel Purple' Osteospermum 'Pinwheel Rose'
Osteospermum 'Pinwheel White Eye' Osteospermum 'Polar Star'
Osteospermum 'Seikilrem (Lemon Symphony)' Osteospermum 'Sparkler'
Osteospermum 'Summeretime Pink Charme' Osteospermum 'Summertime Sweet Blue Sunrise'
Osteospermum 'Summertime Sweet White' Osteospermum 'Tradewinds™ Deep Purple'
Osteospermum 'Tradewinds™ Light Purple' Osteospermum 'Tradewinds™ Pink'
Osteospermum ecklonis Osteospermum ecklonis 'Akope'
Osteospermum ecklonis 'Balostlueye (Blue Eyed Beauty)' Osteospermum fruticosum
Osteospermum fruticosum 'Trailing' Otacanthus caeruleus
Otatea acuminata Othonna capensis
Oxalis crassipes Oxalis oregana
Oxalis purpurea Oxalis purpurea 'Garnet'
Oxalis regnellii Oxalis regnellii 'Atropurpurea'
Oxalis spiralis ssp. vulcanicola Oxalis stricta
Oxalis tetraphylla Oxalis triangularis
Oxalis valdiviensis 'Lucky Gold' Oxalis viops
Oxalis vulcanicola 'Burgundy' Oxalis vulcanicola 'Copper Glow'
Oxalis vulcanicola 'Molten Lava™' Pachycereus hollianus
Pachycereus pringlei Pachycereus schottii
Pachycereus schottii var. monstrosus Pachypodium lealii ssp. saundersii
Pachyrhizus tuberosus Pachysandra procumbens
Pachysandra terminalis Pachysandra terminalis 'Cutleaf'
Pachysandra terminalis 'Foliis Variegatis' Pachysandra terminalis 'Green Carpet'
Pachysandra terminalis 'Green Sheen' Pachysandra terminalis 'Silver Edge'
Pachystachys lutea Packera aureus