In the 16th Century the Spanish conquered the Inca Empire in South America, with this they returned to Europe with a new vegetable; the potato. However, this new produce was not so easily adopted by the rest of Europe, farmers in France in particular were very distrustful.
The farmers considered the vegetable strange and poisonous, even as going as far as claiming the potato caused leprosy and other terrible diseases. The potato was only given to their farm animals and even the poorest, starving peasants were afraid to eat them. The French government was so concerned about the potatoes ill effects that the production and consumption of potatoes was eventually outlawed by the French Parliament in 1748.
Potatoes remained illegal to grow and consume in France for many years until a medical army officer named Antoine Auguste Parmentier was captured by the Prussians during the 7 Year War with England in 1771. Whilst imprisoned Parmentier and his fellow prisoners were fed only potatoes by his captors and, to his surprise, he noted no ill effects as noted by the his government and learned that their perceptions were, in fact, false.
When he returned to France Parmentier wrote a thesis on the benefits of the potato as a food source, he began championing the cause to have the law banning potatoes overthrown and while he was met with resistance by the French populace and even mild hostility, the law was eventually thrown out in 1772.
Once the law was abolished the popularity of the potato in France soared, within 20 years potatoes were being grown on a massive scale, including in the royal gardens in Tuileres Palace in Paris, where the flowers and exotic plants of the gardens were converted into potato fields.