Odontites vernus
Odontites vernus subsp. serotinus
Oenanthe aquatica
Oenothera biennis
Oenothera fallax
Oenothera glazioviana
Oenothera issleri
Oenothera missouriensis
Oenothera rubricaulis
Oenothera sp.
Omphalodes scorpioides
Omphalodes sp.
Omphalodes verna
Onobrychis arenaria
Onobrychis sp.
Onobrychis viciifolia
Ononis arvensis
Ononis sp.
Ononis spinosa
Onopordum acanthium
Opuntia phaeacantha
Orchis purpurea
Origanum vulgare
Orlaya grandiflora
Ornithogalum boucheanum
Ornithogalum kochii
Ornithogalum umbellatum
Orobanche alba
Orobanche caryophyllacea
Orobanche elatior
Orobanche lutea
Orobanche picridis
Orobanche purpurea
Orobanche purpurea subsp. purpurea
Odontites vernus subsp. serotinus
Oenanthe aquatica
Oenothera biennis
Oenothera fallax
Oenothera glazioviana
Oenothera issleri
Oenothera missouriensis
Oenothera rubricaulis
Oenothera sp.
Omphalodes scorpioides
Omphalodes sp.
Omphalodes verna
Onobrychis arenaria
Onobrychis sp.
Onobrychis viciifolia
Ononis arvensis
Ononis sp.
Ononis spinosa
Onopordum acanthium
Opuntia phaeacantha
Orchis purpurea
Origanum vulgare
Orlaya grandiflora
Ornithogalum boucheanum
Ornithogalum kochii
Ornithogalum umbellatum
Orobanche alba
Orobanche caryophyllacea
Orobanche elatior
Orobanche lutea
Orobanche picridis
Orobanche purpurea
Orobanche purpurea subsp. purpurea