Oats, North American Wild Oats, Northern Sea
Oats, River Oats, Sea
Oats, Spanglegrass River Obedient Plant (spp.)
Obedient Plant 'Miss Manners' Obedient Plant 'Mordea Beauty'
Obedient Plant 'Pink Bouquet' Obedient Plant 'Red Beauty'
Obedient Plant 'Summer Snow' Obedient Plant Variegated
Ocotillo Ocotillo Macho
Ocotillo, Tree Ocotillo: macdougalii
Ocotillo: purpusii Octopus Agave
Octopus Plant: actinophylla (spp.) Octopus Tree (spp.)
Ogeechee Lime Ogeechee Tupelo
'Okame' Heavenly Bamboo 'Oklahoma' Rose
Old Fashioned Weigela 'Eyecatcher' Old Fashioned Weigela 'Fine Wine®'
Old Fashioned Weigela 'Ghost™' Old Fashioned Weigela 'Midnight Wine®'
Old Fashioned Weigela 'My Monet™' Old Fashioned Weigela 'Sonic Bloom® Pearl'
Old Fashioned Weigela 'Sonic Bloom® Pink' Old Fashioned Weigela 'Sonic Bloom™ Red'
Old Fashioned Weigela 'Spilled Wine®' 'Old Gold' American Holly
Old Man's Beard Old Man's Beard: virginicus
'Ole' Rose 'Olin Criswell' Daylily
Olive Holly 'Gulftide' Olive Holly 'Kembu'
Olive Leaf Grevillea Olive, Holly Tea 'Gulftide'
Olive, Holly Tea 'Kembu' Olive, Texas Wild
Olive, Wild Olive: americanus, Wild
'Olivia' Indian Hawthorn 'Olympic Fire' Mountain Laurel
'Opera' Butterflybush: hybrid Orange Cestrum
Orange Coneflower 'Goldsturm' Orange Jessamine
Orange Larkspur 'Laurin' Orange Sunflower (spp.)
Orange Sunflower 'Ballerina' Orange Sunflower 'Summer Sun'
Orange Trumpet Orange Wattle
'Orangeade' Rose Orchid, Cradle
Orchid: maxima Oregon Grape 'Skylark'
Oregon Grape (spp.) Oregon Grape 'Compactum'
Oregon Holly Grape (spp.) Oregon Holly Grape 'Compactum'
Oregon Holly (spp.) Oregon Holly 'Compactum'
Oregon Maple Oregon White Oak
Oriental Pear Oriental Photinia
Ornamental Grass (spp.) Ornamental Grass 'Adagio'
Ornamental Grass 'Autumn Light' Ornamental Grass 'Cabaret'
Ornamental Grass 'Cosmopolitan' Ornamental Grass 'Ferner Olsten'
Ornamental Grass 'Gracillimus' Ornamental Grass 'Graziella'
Ornamental Grass 'Huron Sunrise' Ornamental Grass 'Little Dot'
Ornamental Grass 'Malepartus' Ornamental Grass 'Morning Light'
Ornamental Grass 'Purpurascens' Ornamental Grass 'Sarabande'
Ornamental Grass 'Silberfeder' Ornamental Grass 'Strictus'
Ornamental Grass Variegated Ornamental Grass 'Zebrinus'
Ornamental Peach (spp.) Ornamental Peach 'Corinthian Mauve'
Ornamental Peach 'Corinthian Pink' Ornamental Peach 'Corinthian Rose'
Ornamental Peach 'Corinthian White' Ornamental Tobacco (spp.)
Ornamental Tobacco 'Avalon Bright Pink'