1. Low semi-evergreen perennial herb having small spikes of white or pinkish flowers; native to southern United States but grown elsewhere
   - Allegheny spurge, Pachysandra procumbens

Type of: pachysandra

• family Oscillatoriaceae
• family Osmeridae
• family Osmundaceae
• family Osteoglossidae
• family Ostraciidae
• family Ostraciontidae
• family Ostreidae
• family Otariidae
• family Otididae
• family Oxalidaceae
• family Oxyuridae
• family Paeoniaceae
• family Paguridae
• family Palaemonidae
• family Palinuridae
• family Palmaceae
• family Palmae
• family Pandanaceae
• family Pandionidae
• family Panorpidae
• family Papaveraceae
• family Papilionacea
• family Paradisaeidae
• family Paridae
• family Parkeriaceae