Potato
The Potato (Solanum tuberosum) is a perennial herbaceous eudicot cultivar of the nightshade family native to the Andes. Potato plants usually grow about 60cm tall and produces small toxic fruit which bear a vague resemblence to the Tomato plant (a close relative to the Potato). First domesticated around 7,000 to 10,000 years ago Potato plants are cultivated for their starchy tubers, which an individual plant can produce several dozen which contain most of the nutrients that humans require to survive and is a highly productive crop per square kilometer of arable land in temperate lattitudes. Potatoes can be grown from seeds or by clone propagation by planting a tuber or sections of tubers and each plant can be harvested multiple times. The Potato is a common staple foodstuff prepared in a wide variety of ways, including being baked, boiled, mashed and fried in oil.
Hold the Phone!?
You are probably thinking something to the effect of "I'm here reading about wizards and knights and swords and dragons and stuff and out of the blue comes a page about root vegetables? Why the hell is up with this page on regular old root vegetables?" Well it comes down to pedantry.
People often think of potatoes like bowls, hammers and brooms: things that have been around forever and don't need much explanation. Many fantasy writers have served knights baked potatoes at their inns as a background point and even Tolkien had Samwise expounding on the simple joys of a plate of chips. This is contrasted with things like firearms which Everyone Knows is a more recent inventions and the presence of which is seen as a separating point between the Days of Old and the Early Modern World. The rub about Potatoes was that for most people they showed up well after guns did. As mentioned above, Potatoes are native to the Andes region of South America. The first Europeans that ever saw a Potato was Pizarro's gun armed party of Conquistadors in the 1530s. The first Potatoes to reach Eursaia were surplus rations onboard Spanish treasure ships that were sold off and and cultivated by Spanish peasants and grown ornamentally. It took a while for the Potato to catch on since the fruit and the plant's stem and fruit are both toxic, but when it did it was a game changer for European agriculture. It grew well in places where wheat did not, it could be grown in wheat fields when were left fallow and was less susceptible to sudden frosts or armies burning fields. This caused a spike in Europe's population and laid the foundations for the Industrial Revolution.
In short, potatoes did not reach Europe in medieval times. Strictly speaking this is not a problem with most fantasy worlds as it's history is not a one for one parallel with real world history and there is no reason why you can't have Brave Chivalrous Knights, Beautiful Elven mages, Proud Dwarven Guardians and Mighty Orcish Warriors with swords, axes, bows and staff who kick ass, complete quests and celebrate their victories with a basket of fries. It probably means that the population density is a bit higher than the actual middle ages, but this is generally not something to get worked up about in the majority of situations that would be pertinent for most games. If you want for a bit more authenticity you are free to omit them from your game world as well. Which does not stop there are some people from making a stink about it, either in terms of "Why do you have New World cultivars in a pre-columbian world you uneducated peopn!" as well as "Fuck you for saying that ANY game Should EVER be concerned with authenticity or fine details!" in response.
As A Meme
- Potato Song: In the Lord Of The Rings: The Two Towers movie Samwise Gamgee explains to Gollum how you can “boil ‘em, mash ‘em, stick ‘em in a stew” after claiming all he needs is a “few good taters” while Gollum rejects his idea in favor of eating fish raw. This marks the first known cinematic depiction of the cultural conflict between the River Hobbits and the more common Hobbits. This exchange was the inspiration for a famous techno remix on YTMND. Watch it here.
- Death Of Fantasy: In the context of humor, potatoes are apparently the difference between fantasy and fantastic science fiction. This meme persisted on /tg/ for some time, with spoiler tags often being used when not simply the OP idea of the thread in the first place. Whether as magical relics, the creations of a mad wizard, a Pandora’s Box from bored gods, or something Eldritch, the potato discovery is of great importance. While posted constantly in its heyday in a way similar to "Excuse Me" Guy, it never earned the same amount of Skub and had a far shorter lifespan. The image accompanying these threads was usually from the ending of the anime Spice And Wolf where a merchant and his goddess partner obtaining a potato in a box heralds the end of gods and the rise of man.