| Word | Description |
| Parasitic | A plant which lives on, and acquires it's nutrients from another plant. |
| Partially hydrogenated vegetable oil | A semi-solid fat formed by the process of heating an oil and passing hydrogen bubbles through it. The fatty acids in the oil then acquire some of the hydrogen, which makes it more dense. A semi-solid partially hydrogenated oil called trans fat that has a consistency like butter is created. |
| Pesticide | a chemical substance used to kill pests. Pesticide is an umbrella term and encompasses herbicides, fungicides, rodenticides, insecticides, etc. |
| PH | A measure of the acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions, increasing with increasing alkalinity and decreasing with increasing acidity. |
| Photosynthesis | Process by which green plants convert carbon dioxide to sugar and oxygen using sunlight for energy. |
| Phototoxic | a phototoxic substance is a chemical compound which becomes toxic only when exposed to light, i.e. the juices of Hogweed or Parsley. |
| Phytotoxic | a phytotoxic substance is a chemical compound which damages plant tissue |
| Protein | A molecule made up of amino acids that are needed for the body to function properly. Proteins are the basis of body structures such as skin, bone, and hair and are found in substances such as enzymes, hormones and antibodies. |
| Pups | Young plants that form at the base of the “mother” plant |
