When I was in college, one of my teachers assigned us Fernand Braudel's Civilization and Capitalism, a three-volume history of the world between the 15th and 18th centuries. It was incredibly dense, fairly boring and weighed about twenty pounds. I read the whole thing, a feat that still amazes me.
I drank a lot of coffee back then.
While I've managed to forget most of Braudel's opus, I remember that he squeezed out forty pages on the historical influence of the potato. Apparently, potatoes are native to Peru and Bolivia, but Spanish explorers brought them across the Atlantic in 1700. Up to this time, most of Europe's carbohydrates and starch came from wheat, which is work-intensive and produces very little food for every acre planted. Think about it: to make bread from wheat, you need to grow a lot of wheat. You then have to harvest it, thresh it, grind it, mix it with a whole bunch of other ingredients, and bake it. To get a comparable amount of food from a potato, you have to grow a potato, dig it up, clean it off, and pop it in the oven. That's it. Of course, it tastes even better with sour cream and chives.
In 1700, potatoes enabled farmers to grow far more food, with much less work, than any other crop. Across Europe, many farmers switched to potatoes. Because potatoes were so easy to grow, the farmers were able to lay off large numbers of workers. Many of these people ended up moving to the cities, where they provided a huge work force for factories, making cheap manufacturing possible. The upshot is that potatoes are indirectly responsible for the rise of the city and the industrial revolution. Not bad for a lowly tuber.