Solanum tuberosum, known more commonly as the potato, is a delicious edible tuber which has been cultivated in South America for thousands of years. Native Americans discovered it approximately 7,000 years before the birth of Christ, and proceeded to cultivate and breed numerous varieties, which were later imported to Europe by early explorers. Although the potato was not an instant success in Europe, ultimately the tubers became popular in many regional cuisines, and today they are grown and sold all over the world. Sadly, potato biodiversity has suffered in the 20th century, and many unique, exotic, and delicious varieties have been lost forever.
Most markets have potato displays offering several different varieties to choose from. All types break down into two basic categories: starchy, and waxy. Starchy potatoes are highly suited to baking and mashing, while waxy ones hold their shape well when boiled and fried. If you are unsure about whether one is starchy or waxy, a starchy potato will always sink in a brine solution.
The classic potato is the Russet or Idaho, a roughly ovoid brown tuber with starchy white flesh. Numerous varieties of Russets are cultivated around the world, and the durable tuber stores well as long as it is kept in a cool, dark place. Most of those grown in Idaho are Russets, because they hold up well through processing and shipping, and because there is high consumer demand for them.
Another common variety of potato is the Yukon Gold. These are roughly spherical in shape, with dull brown to gold skin. Yukon Golds are usually waxy, and highly delicious in soups, although they will start to break down if cooked for too long. Another similar potato, the Red Bliss, has red flaky skin instead of a smooth yellow outer layer, but also has white flesh. It can sometimes be difficult to discern between Red Bliss and Round Reds, which are waxy boiling potatoes; Round Reds usually have smooth skins.
When it comes to exotic looking options, the natural choice is the Peruvian Purple. Purple potatoes have dark purple skins and pale purple flesh, and the color will be retained through cooking. They are fun when mashed, but are also excellent in roasts, and make an exotic base for potato gratin. The popularity of this distinctive variety began to soar in the 1990s, and most grocery stores and farmers' markets now offer them.
Finally, some potatoes are sold as fingerling or new potatoes. These are exactly what they sound like: potatoes which have not fully matured. They tend to be smaller, and are often used whole in vegetable roasts. New potatoes also have a more delicate flavor, and since waxy varieties are the most common type, they can be used in a variety of dishes, such as roasts, soups, and hashes. They can also be used with their skins, which are thin, delicate, and flavorful.