Sweet Potato vs Yam: Unrelated Plants plus a Store Mix Up
Sweet potato vs yam is a common mix up. A sweet potato is a root from a vine in the morning glory family, while a true yam is a tuber from the Dioscorea genus. Illinois Extension notes the soft orange sweet potatoes in US stores are the ones often labeled yams.
The short answer
Sweet potatoes plus yams are unrelated. Sweet potatoes belong to the morning glory family, have smooth thin skin plus are sweeter. True yams belong to a separate family, have rough scaly skin plus are starchier. Mississippi State University Extension notes few true yams appear in US stores plus the soft orange roots sold as yams are sweet potatoes.
How do sweet potatoes plus yams differ?
Extension sources compare the two crops.
| Trait | Sweet potato | True yam |
|---|---|---|
| Family | Convolvulaceae (Mississippi State University Extension) | Dioscoreaceae (Mississippi State University Extension) |
| Skin | Smooth plus thin (Mississippi State University Extension) | Rough plus scaly (Mississippi State University Extension) |
| Size | Short plus blocky | Up to 5 feet plus 100 pounds (Mississippi State University Extension) |
| Per plant | 4 to 10 roots (Mississippi State University Extension) | 1 to 5 tubers (Mississippi State University Extension) |
| Flavor | Sweeter (Kansas State University) | Less sweet (Kansas State University) |
Sources: Mississippi State University Extension plus Kansas State University.
Where do true yams come from?
Illinois Extension notes yams are monocots native to Africa plus Asia, with more than 600 species in the Dioscorea genus, plus about 95 percent of world production is in Africa. Kansas State University notes yams are related to lilies. Mississippi State University Extension notes few true yams reach US grocery stores.
Why do stores call sweet potatoes yams?
Illinois Extension notes the soft orange sweet potatoes in US stores are the ones commonly called yams in markets.
How to: step by step
- Check the flesh color.
- Examine the skin texture.
- Weigh up shape plus size.
- Grow sweet potatoes as an annual vine.
- Plant after frost danger ends.
- Lift the roots before fall frost.
Troubleshooting
Store sign says yam: market name. Soft orange roots are sweet potatoes.
Root is huge plus scaly: true yam. It is another plant entirely.
Vines die after a cold night: frost tender crop. Wait until frost danger passes to plant.
For related reading see cannabis seed anatomy, cannabis taproot vs fibrous roots plus life cycle of a cannabis plant. Kind Seed Co also stocks cannabis seeds.
Sources
- Sweet potatoes vs. yams: what is the difference?, Mississippi State University Extension
- What is the difference between sweet potatoes and yams?, University of Illinois Extension
- Sweet potatoes vs. yams, Kansas State University
- Ipomoea batatas (sweetpotato), NC State Extension Gardener Plant Toolbox
FAQ
Can yams grow in US gardens?
True yams are tropical. Illinois Extension notes about 95 percent of world yam production is in Africa, plus Mississippi State University Extension notes few true yams appear in US stores. The orange roots most US gardeners call yams are sweet potatoes, which NC State Extension notes are grown as annual vines.
Are sweet potatoes related to potatoes?
No. Illinois Extension notes sweet potatoes are not related to potatoes, which belong to the nightshade family. Sweet potatoes belong to the morning glory family plus form swollen roots, while potatoes form tubers on underground stems. The shared name comes from their similar use in the kitchen, not from botany.
Which is sweeter?
Sweet potatoes. Kansas State University notes sweet potatoes are sweeter than yams, which are starchier plus drier. Mississippi State University Extension describes yams as starchy with rough skin. The soft orange sweet potatoes sold as yams in US stores are among the sweeter types, which adds to the confusion.
How many kinds of true yams are there?
Illinois Extension notes there are more than 600 species of yams in the Dioscorea genus. They are monocots native to Africa plus Asia, plus about 95 percent of world production is in Africa. Kansas State University notes yams are related to lilies, while sweet potatoes belong to the morning glory family.
How are sweet potatoes grown?
NC State Extension notes the sweet potato is a vine in the morning glory family that is frost tender plus grown as an annual. Plant it after frost danger ends so the soil is warm. Mississippi State University Extension notes each plant produces 4 to 10 roots, which form below the vine through summer.
