RUBY CRESCENT (Peruvian), la ratte (French fingerling), parola (German), papa amarillo (Peruvian), and purple Peruvian – all wet in the rain and muddily seductive – were a few of the potato varieties I saw at the Union Square farmers market in Manhattan not too long ago. Thousands of potato varieties are purported to exist, though only six are widely commercially grown in the United States. The potato is considered (largely in french fry form) America's most popular – and the world's most widely consumed – vegetable.

Kin to the tomato, no kin to the sweet potato, and most infamously, both staple food and ruin of the Irish in the 19th century, the hardy tuber originated in the Andean heights (hence the frequency of Peruvian pedigree even in contemporary varieties) and may have been cultivated there as early as 5000 BCE. The ancestors to the smooth, plump ovals we see today were extra knobby and much, much smaller. And their flesh was probably orange and purple and yellow as often as white. When the Spanish conquistadors first saw a stash of potatoes, they purportedly mistook them for truffles. Despite being confused with "the most expensive, subtle and mysterious of the foods known to man" (as described by Alan Davidson), it took the potato a long time to catch on in Europe, especially in the British Isles, where it was later to wreak such havoc. Its odd looks and Incan origins contributed to the Europeans' suspicion about it, and some held that the potato shouldn't be consumed because it isn't mentioned in the Bible. (Are truffles?) Also, the potato, Solanum tuberosum, is from the same family as the nightshade, as in deadly; so are the tomato, eggplant, peppers (chile, jalapeño, etc.), and tobacco. As with the tomato, people feared the potato was poisonous. Until recently I considered raw potatoes a sketchy proposition, but a potato-marketing Web site assured me they are "a nice treat."

The sweet potato, incidentally, also a starchy and nutritious tuber (sometimes incorrectly referred to as a yam, which is a quite different plant), comes from the same family as the morning glory. Though the sweet potato probably originated not too far from the potato and has also been cultivated for thousands of years, it's not the potato's relative. The similar appearances of the two tubers is responsible for verbal confusion of the names used by the Spaniards who brought them to Europe. Sweet potatoes were called by their native West Indies name, batatas, while potatoes were called papas. In English, both came to be known as potato.

Tubers – swollen, underground stems – are basically storage units for plants' nutrient reserves. It stands to reason, then, that the potato is a nutrient powerhouse. Contrary to rumor, it's not potato's skin that holds most of the goodies (though the skin contains most of the its fiber content) but the layer of flesh right underneath it. Potatoes are excellent sources of potassium and vitamins C and B6, and good sources of fiber and some amino acids. I was especially curious about what makes potatoes purple, and whether the color indicates any extraspecial nutrient content. As far as I could find out, the vibrant color probably comes from phytochemicals, the substances that give most fruits and vegetables their mouthwatering array of pigments. Specifically, purple foods contain anthocyanins and phenolics, whose antioxidant properties are being investigated. Yellow potatoes likely contain carotenoids and biflavonoids. More intensely purple and orange potatoes are under development for exponentially more powerful antioxidant potential. With all this nourishment in a neat package, it's no surprise that after the potato caught on in Ireland (in the late 17th century), the Irish population grew tremendously. With a little milk or butter, the potato provided a pretty complete set of nutrients.

Potatoes and milk and butter are seemingly so simple, yet in combination are considered by some to be the holy grail of potato dishes. The creation of perfect mashed potatoes has generated much rumor, heated discussion, and writing (see Jeffrey Steingarten's manifesto "Totally Mashed" in The Man Who Ate Everything). Conventional wisdom has it that potatoes with high starch content, such as the ubiquitous russets, make fluffy mashed potatoes. Low-starch potatoes, also known as waxy potatoes, such as yellow Finn, and most red-skinned or purple potatoes, are held to be better for boiling, as they keep their shape. Medium-starch potatoes, such as my beloved Yukon Gold, are supposedly good for all manner of preparation, and they are known in potato lingo as all-purpose. Of course, I encourage potato-variety experimentation, for fun, flavor, and self-preservation.

As we know today, the Irish famine was caused by a fungus (known as the blight), which was likely imported from South America. Because the potato crop in Ireland was basically a monoculture (i.e., they grew mainly one potato variety), there were no blight-resistant varieties on the island, and pretty much the entire supply of potato plants was wiped out. The people that depended on the potato plants perished along with them. Long live diversity.

E-mail Masha Gutkin at lydialeapfrog@yahoo.com.