Most of the time, both terms ‘yam’ and ‘sweet potato’ are being used interchangeably, although they are very different vegetables.

Sweet Potatoes

Sweet Potato is a dicot (have two seed leaves) plant which belongs to a Convolvulacea or morning glory family.

They are popular in South America. They are yellow or orange in colour and elongated with ends that taper to a point.

One of the types is a paler-skinned potato that has a light yellow, thin skin with pale yellow flesh. This type is not sweet, but it has dry, crumbly texture.

The other type is a darker-skinned and most people get confused and call it as a ‘yam’. This type has reddish to darker orange colour and thicker skin with orange, sweet flesh and a moist texture.

The types of sweet potatoes are classified as either ‘soft’ or ‘firm’. When it is cooked, ‘soft’ types becomes soft and moist whereas the ‘firm’ category stays firm.

The types of sweet potatoes include Centennial, Goldrush, New Jersey, Velvet, Georgia Red and Puerto Rico.

Yams

Yams are monocots and belong to a Yam family or the Dioscoreaceae and they are not related to the sweet potato family at all.

They are popular in US, Latin America and Caribbean and there are more than 150 types available. They are sweeter than the sweet potato and can grow over seven feet in length.

The yam can have brown or black skin colour with purple or red flesh depending on the type. They have more natural sugar than sweet potatoes and also have higher moisture content.

The types of ‘yams’ include

Dioscorea alata- water yam, winged yam, purple yam
Dioscorea opposita- Chinese yam (in China)
Dioscorea bulbifera- air potato (found in both Africa and Asia)
Dioscorea esculenta- lesser yam
Dioscorea trifida- cush-cush yam (South America)
Dioscorea dumetorum- bitter yam (West Africa)