Odontites vernus
Red Bartsia
Oenanthe crocata
Hemlock Water-dropwort
Oenanthe fistulosa
Tubular Water-dropwort
Oenanthe lachenalii
Parsley Water-dropwort
Oenanthe pimpinelloides
Corky-fruited Water-dropwort
Oenanthe silaifolia
Narrow-leaved Water-dropwort
Oenothera biennis
Small-flowered Evening-primrose
Onobrychis viciifolia
Sainfoin
Ononis reclinata
Small Restharrow
Ononis repens
Common Restharrow
Ononis spinosa
Spiny Restharrow
Ophrys apifera
Bee Orchid
Origanum vulgare
Wild Marjoram
Ornithogalum pyrenaicum
Spiked Star-of-Bethlehem
Ornithogalum umbellatum
Star-of-Bethlehem
Orobanche caryophyllacea
Bedstraw Broomrape
Orobanche hederae
Ivy Broomrape
Orobanche minor
Common Broomrape
Orobanche rapum-genistae
Greater Broomrape
Orthilia secunda
Serrated Wintergreen
Oxybasis glauca
Oak-leaved Goosefoot
Papaver lecoqii
Yellow-juiced Poppy
Parentucellia viscosa
Yellow Bartsia
Parietaria judaica
Pellitory-of-the-wall