1. Lacking a head or a clearly defined head
   "acephalous worms"

See also: headless

• family Plasmodiophoraceae
• family Plataleidae
• family Platanaceae
• family Platanistidae
• family Platycephalidae
• family Plethodontidae
• family Pleurobrachiidae
• family Pleuronectidae
• family Ploceidae
• family Plumbaginaceae
• family Pluteaceae
• family Poaceae
• family Podargidae
• family Podicipedidae
• family Podocarpaceae
• family Poeciliidae
• family Polemoniaceae
• family Polyangiaceae
• family Polygalaceae
• family Polygonaceae
• family Polynemidae
• family Polyodontidae
• family Polypedatidae
• family Polypodiaceae
• family Polyporaceae