Oreopteris limbosperma
Lemon-scented Fern
Origanum vulgare
Wild Marjoram
Ornithopus perpusillus
Bird's-foot
Orobanche caryophyllacea
Bedstraw Broomrape
Orobanche hederae
Ivy Broomrape
Orobanche minor
Common Broomrape
Orobanche rapum-genistae
Greater Broomrape
Orthilia secunda
Serrated Wintergreen
Osmoxylon lineare
Green Aralia
Osmunda regalis
Royal Fern
Oxalis acetosella
Wood-sorrel
Oxalis articulata
Pink-sorrel
Oxalis incarnata
Pale Pink-sorrel
Oxybasis glauca
Oak-leaved Goosefoot
Oxybasis rubra
Red Goosefoot
Pancratium maritimum
Sea Daffodil
Papaver cambricum
Welsh Poppy
Paphiopedilum callosum
Callus Paphiopedilum
Paphiopedilum hirsutissimum
Parentucellia viscosa
Yellow Bartsia
Parietaria judaica
Pellitory-of-the-wall
Paris quadrifolia
Herb-paris
Parnassia palustris
Grass-of-Parnassus
Pastinaca sativa
Wild Parsnip