Oenothera glazioviana
Large-flowered Evening-primrose
Oenothera stricta
Fragrant Evening-primrose
Olearia macrodonta
New Zealand Holly
Onobrychis viciifolia
Sainfoin
Ononis arvensis
Ononis reclinata
Small Restharrow
Ononis repens
Common Restharrow
Ononis spinosa
Spiny Restharrow
Ophrys apifera
Bee Orchid
Ophrys fuciflora
Late Spider-orchid
Ophrys insectifera
Fly Orchid
Ophrys insectifera x apifera
Ophrys sphegodes
Early Spider-orchid
Orchid 'Butterfly Wings'
Orchis mascula
Early-purple Orchid
Orchis militaris
Military Orchid
Orchis purpurea
Lady Orchid
Orchis simia
Monkey Orchid
Orchis x angusticruris
Lady#Orchid#/ Monkey#Orchid#hybrid
Origanum vulgare
Wild Marjoram
Ornithogalum nutans
Drooping Star-of-Bethlehem
Ornithogalum pyrenaicum
Spiked Star-of-Bethlehem
Ornithogalum umbellatum
Star-of-Bethlehem
Ornithopus perpusillus
Bird's-foot