1. Southern African herb with white bell-shaped flowers
   - summer hyacinth, cape hyacinth, Galtonia candicans

Type of: hyacinth

• genus Oryzomys
• genus Oryzopsis
• genus Osmanthus
• genus Osmerus
• genus Osmunda
• genus Ostrea
• genus Ostrya
• genus Ostryopsis
• genus Otaria
• genus Othonna
• genus Otis
• genus Otus
• genus Ouranopithecus
• genus Ovalipes
• genus Ovibos
• genus Ovis
• genus Oxalis
• genus Oxandra
• genus Oxybelis
• genus Oxydendrum
• genus Oxylebius
• genus Oxytropis
• genus Oxyura
• genus Oxyuranus
• genus Ozonium