Olearia macrodonta
New Zealand Holly
Onobrychis viciifolia
Sainfoin
Ononis arvensis
Ononis reclinata
Small Restharrow
Ononis repens
Common Restharrow
Ononis spinosa
Spiny Restharrow
Ophioglossum azoricum
Small Adder's-tongue
Ophioglossum vulgatum
Adder's-tongue
Ophrys apifera
Bee Orchid
Ophrys fuciflora
Late Spider-orchid
Ophrys insectifera
Fly Orchid
Ophrys insectifera x apifera
Ophrys sphegodes
Early Spider-orchid
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
Oreopteris limbosperma
Lemon-scented Fern
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