|
What is the Difference
Between a Sweet Potato
and a Yam?
From top left clockwise -
Yellow-Fleshed Yam, Boniato, White- Fleshed Yam, sweet potato |
True Yam
|
The Confusion Between
Sweet Potatoes and Yams
What’s in a name? When it comes to the yam, a bit of confusion. What is marketed in the United States as “yams” are really a variety of sweet potato, grown in the South. A true yam is a starchy edible root of the Dioscorea genus, and is generally imported to America from the Caribbean. It is rough and scaly and very low in beta carotene.
“Yams,” as the industry and general public perceives them, are actually sweet potatoes with a vivid orange color and a soft moist consistency when cooked, and tend to have a sweeter flavor. Other varieties of sweet potatoes are lighter skinned and have a firmer, drier texture when cooked. Sweet potatoes are smooth with skins that can vary in color, depending on the variety, from pale yellow to deep purple to vivid orange. Flesh colors can range from light yellow to pink, red or orange.
So where did all of the confusion come from? Several decades ago when orange flesh sweet potatoes were introduced into the southern United States, producers and shippers desired to distinguish them from the more traditional white flesh types. The African word "nyami" referring to the starchy, edible root of the Dioscorea genus of plants was adopted in its English form, "yam".
Yams in the United States are actually sweet potatoes with relatively moist texture and orange flesh. Although the terms are generally used interchangeably, the US Department of Agriculture requires that the label "yam" always be accompanied by "sweet potato."
The following information outlines several differences between sweet potatoes and yams.
| Factor |
Sweet Potato |
Yam |
| Scientific name |
Ipomoea batatas |
Dioscorea Species |
| Plant Family |
Morning Glory Convolvulaceae |
Yam (Dioscoreaceae) |
| Plant Group |
Dicotyledon |
Monocotyledon |
| Chromosome number |
2n=90 (hexaploid) |
2n=20 |
| Flower character |
Monoecious |
Dioecious |
| Origin |
Tropical America(Peru,Ecuador) |
West Africa,Asia |
| Historical beginning |
Prehistoric |
50,000 BC |
| Edible storage organ |
Storage root |
Tuber |
| Number/plant |
4-10 |
1-5 |
| Appearance |
Smooth, with thin skin |
Rough, scaly |
| Shape |
Short, blocky, tapered ends |
Long, cylindrical,some with "toes" |
| Dry Matter |
22-28% |
2-35% |
| Mouth feel |
Moist* |
Dry |
| Taste |
Sweet* |
Starchy |
| Beta carotene (Vit.A) |
High (orange vars.)* |
Very low |
| Propagation |
Transplants/vine cuttings |
Tuber pieces |
| Growing season |
90-150 days |
180-360 days |
| Maturity |
None |
At senescence |
| Storage |
(Cured at 80-86F) 55-60F. |
54-61 F. |
| Climatic requirements |
Tropical and temperate |
Tropical |
| Availability |
Grown in USA |
Imported from Carribean |
*Characteristic of most SweetPotato varieties grown in United States.
Information Courtesy of: Department of Horticultural Science North Carolina State University
|
