Osage Orange (spp.) Osage Orange 'Double O'
'Osaka Purple' Mustard Greens 'Oscar' Hybrid Tulip
'Oshi Rini' Japanese Maple 'Oshio beni' Japanese Maple
Osmanthus, Roundleaf Holly Osmoxylon
'Oso Easy® Cherry Pie' Rose 'Oso Easy® Honey Bun' Rose
'Oso Easy® Lemon Zest' Rose 'Oso Easy® Mango Salsa' Rose
'Oso Easy® Strawberry Crush' Rose 'Oso Easy™ Paprika' Rose
'Oso Easy™ Peachy Cream' Rose 'Oso Easy™ Fragrant Spreader' Rose
'Oso Happy® Candy Oh!' Rose 'Oso Happy® Petit Pink' Rose
'Oso Happy® Smoothie' Rose 'Osprey' Hybrid Spiderwort
'Ospring' Chinese Holly 'Ostbo Red' Mountain Laurel
Ostrich Fern Ostrich Plume 'Ostrich Plume™'
'Ostrich Plume™' Ostrich Plume Oswego Tea (spp.)
Oswego Tea 'Jacob Cline' Oswego Tea 'Marshal's Delight'
Oswego Tea 'Panorama' Oswego Tea: Monarda 'Colrain Red'
Oswego Tea: Monarda 'Donnerwolke' Oswego Tea: Monarda 'Petite Wonder'
Oswego Tea: Monarda 'Raspberry Wine' Otaheite Apple
Oteniqua Yellowwood 'Othello' Leopard Plant: dentata
Othonna, Cape 'Oto hime' Japanese Maple
'Otome' Azalea 'Otome zakura' Japanese Maple
'Ottawa' Siberian Iris 'Otto Luyken' Cherry Laurel
'Otto Quast' French Lavender 'Otto's Dissectum' Japanese Cutleaf Maple
Outeniqua Pincushion Oval Kumquat
Oval-leaf Mintbush Oval-leaved Viburnum
Oven's Wattle 'Golden Carpet' 'Over in Gloryland' Siberian Iris
Overcup Oak (spp.) Overcup Oak 'Highbeam®'
Ox Eye Daisy Ox Eye (spp.)
Ox Eye 'Ballerina' Ox Eye 'Summer Sun'
Ox Eye: helianthoides scabra (spp.) Ox Eye: helianthoides scabra 'Gold Greenheart'
Ox Tongue Plant Ox Tongue Plant: spp.
Oxalis (spp.) Oxalis 'Garnet'
Oxalis: spiralis vulcanicola Oxalis: stricta
Oxalis: vulcanicola 'Copper Glow' Oxalis: vulcanicola 'Molten Lava™'
'Oxfordshire' Rose Oxhorn Bucida (spp.)
Oxhorn Bucida 'Shady Lady' Oyama Magnolia
Oyster Bay Cypress Pine Oyster Plant (spp.)
Oyster Plant 'Fielding Gold' Oyster Plant Variegated
Oyster Plant: spathacea (spp.) Oyster Plant: spathacea 'Nana Tricolor'
Oysterwood Ozark Coneflower
Ozark (spp.) 'Ozark Spring' Crapemyrtle: indica
Ozark Sundrops (spp.) Ozark Sundrops 'Silver Wings'
Ozark 'Autumn Embers' Ozark 'Carnea'
Ozark 'Christmas Cheer' Ozark 'Purpurea'
Ozark 'Sandra' 'P.G. Pee Wee' Panicle Hydrangea