P to Palisade

Pall to Paper Mulberry

Paper Tigers to Parkinson's disease

Parkinsonia to Paternalism

Paternoster to Pecan pie

Peccary to Pennsylvania

Pennsylvania Dutch to Perisoreus

Peristalsis to Peyote

Pfennig to Phoca

Phocas to Phytoplankton

Pi to Pillory

Pillow to Piquet

Piracy to Plastic bag

Plastic explosive to PLUS

Plus fours to Polemoniaceae

Polemonium to Polypropylene

Polystichum to Porosity

Porphyria to Potato

Potato chip to Presbyterianism

Presence to Procellariiformes

Process to Proton accelerator

Protractor to Puerto Rico

Puffball to Pygoscelis

Pyloric stenosis to Pyx