You’re standing in the produce aisle. You see a pile of tubers with copper skin and orange flesh labeled "Yams." Right next to them, there’s another pile that looks almost identical labeled "Sweet Potatoes." You’re confused. Honestly, everyone is.
So, are sweet potatoes yams?
Short answer: No. Not even close. In fact, they aren't even distantly related in the plant kingdom.
📖 Related: Designs for Graph Paper: Why Most People Are Still Using the Wrong One
Botanically, sweet potatoes (Ipomoea batatas) belong to the morning glory family. Yams (Dioscorea) are more like lilies or grasses. They are as different as an apple and an onion. But if you're in a typical American grocery store, those "yams" you're looking at are almost certainly just another variety of sweet potato. It’s a marketing lie that’s been running for over a century, and it has fundamentally broken the way we talk about dinner.
The Great American Naming Blunder
How did we get here? It wasn't an accident. It was a branding strategy.
Decades ago, when orange-fleshed sweet potatoes were first introduced commercially in the United States, they needed a way to stand out from the firmer, white-fleshed varieties people were used to. Producers started calling the soft, orange ones "yams" to distinguish them. The word itself comes from West African languages—nyami or nyam—which basically means "to eat." Enslaved Africans saw the familiar-looking sweet potatoes in the South and called them by the name of the vegetable they knew back home.
The USDA actually requires that if a label says "yam," it must also include "sweet potato" nearby if it's not a true yam. Look closely at the fine print next time you buy a can of Bruce’s. It’s there.
What a Real Yam Actually Looks Like
If you ever stumble across a true yam, you'll know it immediately. They don't look like something you'd want to marshmallow-top for Thanksgiving.
- The Texture: True yams have bark-like skin. It’s rough, brown, and hairy. You might need a serious knife or even a vegetable cleaver to get through it.
- The Interior: The flesh is usually white, purple, or reddish, but rarely that bright pumpkin-orange we associate with "yams" in the U.S.
- The Size: These things can get massive. While a sweet potato fits in your hand, a true yam can grow several feet long and weigh over 100 pounds.
- The Taste: They are starchy. Very starchy. They lack the high sugar content of a sweet potato. Think of them more like a yuca root or a very dry potato. They need to be boiled, fried, or pounded into a paste like fufu.
You won't find these at a standard Kroger or Safeway. You have to head to international markets, specifically those specializing in Caribbean, West African, or Asian cuisines.
The Sweet Potato Spectrum
Since we’ve established that almost everything you see is a sweet potato, let's talk about the variations. There are thousands of varieties, but you usually only see three or four.
The Beauregard
This is the one you know. It’s got that dusky red skin and bright orange insides. It’s sweet, it’s stringy, and it turns into mush (the good kind) when you roast it.
The Jewel and Garnet
Similar to the Beauregard but with slight variations in skin thickness and moisture content. If you're making a pie, these are your best friends.
Japanese Sweet Potatoes (Satsumaimo)
These are the elite tubers. Purple skin, pale yellow flesh. When you roast them, they become incredibly creamy and taste almost like roasted chestnuts or vanilla custard. They aren't "yams" either, though they are often mislabeled in specialty shops.
Stokes Purple
These are dense. They have purple skin and deep, vibrant purple flesh that stays purple after cooking. They are packed with anthocyanins—the same stuff in blueberries—and they are much drier than the orange ones.
Why the Confusion Persists
It’s about culture and habit. If your grandma called them yams, you’re going to call them yams.
The culinary world doesn't help. Even famous chefs often use the terms interchangeably in recipes. But from a nutritional and agricultural standpoint, the distinction matters. Sweet potatoes are packed with Vitamin A (beta-carotene), which gives them that orange hue. True yams have very little Vitamin A but are higher in potassium and fiber.
Interestingly, true yams contain a compound called diosgenin, which was actually used in the early development of birth control pills. You won't find that in your sweet potato fries.
How to Shop Like an Expert
Stop looking at the big signs and start looking at the produce itself.
If the skin is smooth and thin enough to peel with a standard peeler, it’s a sweet potato. If the skin looks like it belongs on a tree trunk in the Amazon, you’ve found a true yam.
Most people actually prefer sweet potatoes because they are easier to cook. A true yam requires specific preparation—usually peeling, soaking, and boiling—to remove naturally occurring plant toxins and to soften the intense starchiness. You can't just toss a true yam in the microwave for five minutes and expect a snack. It won’t happen. You’ll just have a hot, hairy rock.
👉 See also: How to Convert 100 C to F and Why This Specific Number Matters So Much
Cooking the Difference
If you're making a traditional West African dish like Punyam, you need the real deal. Sweet potatoes will disintegrate and become too sweet, ruining the savory balance of the dish.
On the flip side, if you try to use a real yam for a "Yam Soufflé," your guests will be very confused. It won't be sweet, and the texture will be grainy rather than silky.
Quick Identification Guide
- Skin Check: Smooth/Paper-thin = Sweet Potato. Rough/Scaly = True Yam.
- Shape Check: Tapered ends = Sweet Potato. Cylindrical/Blocky = True Yam.
- Location: Bulk bin next to onions = Sweet Potato. Tropical/International section = True Yam.
The Nutrition Factor
If you're eating for health, the orange sweet potato is a powerhouse. One medium sweet potato provides over 400% of your daily Vitamin A needs. True yams are great for energy because of their complex carbohydrates, but they don't offer the same antioxidant profile.
Don't let the "yam" label scare you off if you're watching your glycemic index. While sweet potatoes are "sweet," they actually have a lower glycemic index than regular white potatoes when boiled. Roasting them increases the GI because the starches convert to sugars, but they are still a nutritionally dense choice regardless of what the sign in the store says.
Your Next Steps for Tubers
Stop calling them yams unless you are actually holding a piece of Dioscorea. It’s a small hill to die on, but accuracy matters in the kitchen.
🔗 Read more: Long for as Attention NYT: Why We Are All Addicted to the Scroll
Go to an international grocery store this weekend. Search for a real yam. Buy a small piece, peel it (be careful, some people get a slight skin itch from the raw starch), boil it in salted water, and mash it with a bit of butter and black pepper. Compare that experience to the sweet, orange mash you're used to. You'll never confuse the two again.
Check your pantry. If you have "canned yams," read the ingredient list. You will see "Sweet Potatoes" listed as the first ingredient. Use this knowledge to win your next Thanksgiving trivia debate or simply to understand why your "yam" fries taste so much like... well, sweet potatoes.