Sweet potato vs. yam: what’s the difference?

Short answer

They’re different plants. True yams come from Africa and Asia, have rough, bark-like skin and starchy, drier flesh, and in the US are usually found in international markets. The orange “yams” in most US supermarkets are soft sweet potatoes. When a store calls a sweet potato a yam, the USDA requires the label to say “sweet potato” too.

How to tell them apart

Why stores call sweet potatoes yams

Firm sweet potatoes were grown in the US first. When soft, orange varieties were grown commercially, growers needed a way to tell them apart. Enslaved Africans had already called the soft ones “yams” because they resembled African yams, and the name stuck. Today the label has to say “sweet potato” as well.

How to store sweet potatoes

Don’t refrigerate them raw: cold below about 50–55°F can give them a hard core and an off flavor after cooking. Keep them unwrapped somewhere cool, dry and dark (55–60°F, like a cool pantry or basement) and they keep up to two months. On a warm kitchen counter, plan on about a week. Scrub them under running water just before cooking.