Plants starting with O
- Oenothera berlandieri 'Siskiyou' Evening Primrose
- Oenothera macrocarpa fremontii 'Silver Wings' Evening Primrose
- Oenothera macrocarpa sub incana 'Silver Blade®' Evening Primrose
- Oenothera missouriensis Missouri Evening Primrose
- Oenothera missouriensis 'Evening Sun' Evening Primrose
- Oenothera pallida Pale Evening Primrose
- Oenothera speciosa 'Turner01' Twilight Evening Primrose
- Oenothera tetragona fruticosa 'Sundrops' Narrowleaf Evening Primrose
- Ophiopogon planiscapus 'Nigrescens' Black Mondo Grass
- Opuntia Walk in Beauty™ 'Apricot Glory' Prickly Pear Cactus
- Opuntia Walk in Beauty™ 'Garnet Glow' Prickly Pear Cactus
- Opuntia Walk in Beauty™ 'Mandarin Sunrise' Prickly Pear Cactus
- Opuntia Walk in Beauty™ 'Ruffled Papaya' Prickly Pear Cactus
- Opuntia Walk in Beauty™ 'Watermelon Man' Prickly Pear Cactus
- Osteospermum '4D™ Purple' African Daisy
- Osteospermum '4D™ White' African Daisy
- Osteospermum 'Akila® Grand Canyon Mix' African Daisy
- Osteospermum 'Akila® Purple' African Daisy
- Osteospermum 'Akila® Sunset Shades' African Daisy
- Osteospermum 'Akila® White' African Daisy
- Osteospermum 'Avalanche' Hardy African Daisy Sun Daisy
- Osteospermum 'P006S' Lavender Mist™ Purple African Daisy
- Osteospermum barberiae var compactum 'P005S' Purple Mountain® Sun Daisy
- Ostrya virginiana Hop Hornbeam