Potatoes (Solanum tuberosa) All of the potatoes grown here are cultivars of this one species which was first cultivated in Peru 7000 to 10000 years ago. The people in Peru grew many other species besides S tuberosa. They grew their crops from seeds, rather than cloning them from saved tubers, leading to high genetic diversity.
Potatoes were brought to Spain by the late 1500s, and spread around Europe from there. People were very suspicious of them at first. After all, they were related to deadly nightshade. All parts of the plant except the tubers are poisonous. But potatoes are easy to grow, and don’t need as much space a grain.
Frederic the Great of Prussia recognised the advantages of potatoes, and tried to get his subjects like them, without much success. The story is that he grew them in heavily guarded fields, but left them open at night. People assumed potatoes must be very valuable, so they stole them, tried them out in their own gardens, and decided they were OK. By the early 1800s potatoes were an important crop all through Europe.
Because potatoes were so easy to grow, cropping more reliably than grain, and needing less space they became the main source of food for poor peasants all over Europe, but especially in Ireland. The extra nutrition from potatoes allowed the population there to double in the century before 1845. That year was the beginning of the disastrous famine caused by late blight (Phytophthera infestans). All the potatoes grown were of the only variety available: “Irish lumpers”, which matured late in the season and had no blight resistance. Already desperately poor peasants had literally nothing to eat. The true death toll is still not known.
Today China and India lead the world in potato production, with over 350 million tonnes.