The potato (Solanum tuberosum) is a perennial plant of the Solanaceae, or nightshade, family, commonly grown for its starchy tuber. Potatoes are the world's most widely grown tuber crop, and the fourth largest crop in terms of fresh produce (after rice, wheat, and maize), but this ranking is inflated due to the high water content of fresh potatoes relative to that of other crops. The potato originated somewhere in south west South America, probably Peru or Chile.[citation needed] Potatoes are important to the culture of the Andes, where farmers grow many different varieties that have a remarkable diversity of colors and shapes. Potatoes spread to the rest of the world after European contact with the Americas in the late 1400s and early 1500s and have since become an important field crop. The potato is also often strongly associated with Idaho, United States, Prince Edward Island, Canada, Ireland, and Russia.