You’re probably familiar with the little pits and indents on a potato’s surface we typically refer to as “eyes.” But have you ever wondered why potatoes have eyes—or why they’re even called eyes in the first place?
Potatoes, which are native to the Peruvian-Bolivian Andes and spread to Europe starting in the 16th century, are one of the world’s primary food crops. In fact, potatoes are third in importance for human consumption after only rice and wheat, according to the research-for-development organization, the International Potato Center. And potatoes’ eyes, it turns out, has a lot to do with their robustness and longevity as a crop.
Nature is smart; the vast majority of odd-seeming features with which both animals and plants come equipped usually exist for perfectly good reasons—often ones that have to do with the creature’s continued survival. This is true of potatoes, whose eyes are essential to potato reproduction.
Here’s everything you ever wanted to know about potato eyes—and probably a lot of stuff you didn’t even know you wanted to know, too.
The Eyes Have It
The actual function of potato eyes is incredibly simple: They’re how new potatoes grow. They’re actually called buds, technically speaking, but they earned their ocular nickname due to their resemblance to—yes—eyes on a face. According to The Biology of Horticulture by John E. Preece and Paul E. Read, the “eyes” themselves are the potato’s axillary buds, while the vestigial leaf scars located nearby form the “eyebrows.”
Potato anatomy is generally divided into four different areas, per the Food and Agriculture Organization of the United Nations: The medullar rays and medulla (AKA the pith), which runs up through the center of the potato; the parenchyma tissue, which makes up the bulk of the potato itself; the ring of vascular bundles, which surrounds the parenchyma tissue; and the skin or periderm, which comprises the outer layers of the potato. Potatoes also have two distinct ends: The stem end and the bud end. The stem end is the end of the potato that’s attached to the rest of the potato plant while the tuber is growing; the bud end, meanwhile, is where the buds form—that is, it’s where you’ll find most of the potato’s eyes. Individual tubers typically have between two and ten buds or eyes spiraling around their surfaces, according to the International Potato Center.
The eyes of a potato might initially just look to you like little dimples in the potato’s surface—but when they start to sprout, that’s a sign that the potato itself is ready to grow new tubers.
How Potatoes Grow
After potatoes are harvested, they tend to go into a dormancy period—that is, they aren’t growing, but instead storing their energy for the future. When the right conditions are met, however—usually when a potato is stored at a temperature between 50 and 70 degrees Fahrenheit, and there’s at least some humidity in the environment—the dormancy period will end. The potato will begin converting its starches into sugars, thus providing fuel and energy for sprouts to emerge from the buds.
If a sprouted potato is planted during the right season and in the correct climate, it can then grow a plant that will, in turn, produce more potatoes. The planted potato becomes what’s called the mother tuber—the tuber from which the entire rest of the potato plant grows. Above the ground, you’ll see stems, leaves and leaflets, small fruits, and flowers; meanwhile, below the ground, the mother tuber sits at the heart of the plant, with everything above the ground growing up from it and both the roots of the plant and a variety of underground stems called stolons growing out from it. At the ends of the stolons, the new potatoes will form.
This method of potato reproduction, termed vegetative reproduction, isn’t the only way potatoes can reproduce; the fruits of the potato plant do produce seeds. However, plants grown from these seeds “develop into a plant with unique characteristics,” notes a paper on potato propagation published on the North Dakota State University’s website—that is, the plants that grow from seeds harvested from potato plant fruits could be very different both from the plant that actually produced the seeds and from other plants grown from those same seeds. As such, potatoes grown from seeds aren’t much use as a food crop, which is why potatoes grown for agricultural and food supply purposes are typically grown via vegetative reproduction. However, notes the paper, potatoes grown from seeds can be useful for breeding programs researching ways to improve crops.
Is It Safe to Eat Sprouted Potatoes?
One frequently-asked question regarding potatoes and their eyes has to do with whether it’s okay to eat a potato with eyes that have sprouted. It’s an understandable query; after all, sprouted potatoes do sometimes resemble nothing so much as a strange, new alien life form that has recently found its way to Earth. It turns out, though, that there’s good reason to ask this question besides a sprouted potato’s bizarre appearance.
As Healthline notes, potatoes, like other foods, including eggplants and tomatoes, contain two glycoalkaloid compounds: solanine and chaconine. These compounds are safe to eat in small quantities, and indeed, can even be beneficial—they’re known for their antibiotic properties and their ability to lower blood sugar and cholesterol levels. But in high quantities, these compounds can become toxic when consumed.
Here’s where the concern comes into play. As potatoes sprout, their glycoalkaloid content rises—so if you eat potatoes that are too far along in the sprouting process, you risk consuming higher-than-recommended levels of glycoalkaloids. According to the non-profit organization, the National Capital Poison Center, symptoms of consuming too much of these compounds can include vomiting, abdominal pain, diarrhea, headaches, confusion, and fever. These symptoms can develop anywhere from a few hours to a day after consumption.
Most experts agree, however, that unless a sprouted potato is also shriveled, wrinkled, soft, or green or otherwise discolored, it’s still safe to eat as long as you cut the sprouts and eyes out beforehand. (The pointy bit at the end of your vegetable peeler can help with that.) As Nora Olsen, a potato specialist at the University of Idaho told Eat or Toss in 2019, “Little sprouts”—ones that are only small buds, about the size of the tip of a pen—“are not adding any major concerns”; she even said that she “frequently [eats] potatoes with sprouts like this,” removing the sprouts and cutting out the eyes during cooking. Dr. Benjamin Chapman, an associate professor and food safety specialist at North Carolina State University, similarly noted to Iowa State University’s AnswerLine in 2017 that potatoes with small sprouts are safe to eat, provided the potato is still firm, and you cut out the sprouts and eyes.
Generally, a good rule to follow is that if the potato tastes bitter or looks, feels, or smells otherwise “off”—don’t eat it. And, when in doubt, err on the side of caution.
How to Grow Sprouted Potatoes
Although it’s not generally recommended that you attempt to grow potatoes whose eyes have sprouted if you originally bought the potatoes at a grocery store, potatoes themselves are pretty easy to grow.
Grocery store potatoes are often treated to make them less susceptible to sprouting, hence why they’re not great choices for growing. Instead, Steven B. Johnson, Ph.D., a crops specialist at the University of Maine Extension, recommends buying certified seed potatoes from reputable seed sellers. These are not the seeds produced by the fruit of a potato plant, but rather pieces of actual potato tubers with one or more eye. If your seed potato is less than two inches in diameter, you can plant it whole; if it’s larger, though, you’ll want to cut it into smaller pieces, making sure each piece has at least one eye.
According to Garden Gate Magazine, seed potatoes are best planted in the early spring, or whenever temperatures in your area get to about 50 degrees Fahrenheit. They’ll need lots of sun and well-drained soil to grow; you’ll also want to make sure they get plenty of water. You’ll be able to tell when your potatoes are ready to harvest—usually about two to four months after planting, per The Spruce’s guide to growing potatoes—when the plant visible above the ground’s surface starts to grow yellow and die.
For more tips on how to grow your own potatoes, check out this comprehensive guide from Cornell University’s garden-based learning program. Good luck!