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n. Any toxic substance produced by a plant

n. A vegetable toxin, such as abrin, ricin, crotin, etc.

n. any substance produced by plants that is similar in its properties to extracellular bacterial toxin

"Years later I learned that CuCl is a known phytotoxin and is used to control algae blooms in waterways and to kill roots in drain pipes."

toxin   

mycotoxin    nicotine    brucine    strychnine    hemlock