The reason why it was illegal to grow potatoes in France is due to widespread superstitions as well as fears of disease and visual prejudices.
The French Parliament banned the growth and cultivation of potatoes in France between the years of 1748 to 1772.
The main reasons for the ban on growing potatoes in France was because of a fear of leprosy, botanical suspicion and religious superstition.
People had noticed that the bumpy, gnarled texture of some potatoes resembled the hands and the skin of people that suffered from leprosy.
And these people had incorrectly believed that the tubers had spread the leprosy disease.
Botanists also had realized that the potato plant belonged to the nightshade family, which contains poisonous toxins, which led to suspicions that eating potatoes would cause death or illness.
And because the potatoes grow underground and are not mentioned in the Bible, some clergymen also viewed potatoes as being unholy or even being associated with witchcraft.
However the ban on growing potatoes in France was lifted eventually due to the efforts of the Antoine Augustine Parmentier, which was a French army medical officer.
While imprisoned in Prussia during the Seven Years War, Antoine Augustine Parmentier, was forced to eat potatoes and realized that the potatoes were actually safe and highly nutritious.
And upon his return to France, he heavily promoted the potatoes, famously using a clever marketing trick of stationing armed guards around his potato fields to make peasants believe that the potato crop was incredibly valuable, which also prompted them to steak and cultivate the potatoes.