The sweetpotato (Ipomoea batatas, morning-glory family) is an enlarged storage root that comes in various shapes, sizes, and colors. Varieties, particularly those used for market use, are classified as “dry-fleshed” or “moist-fleshed,” according to the feel sensation experienced in the mouth when eating a cooked or baked sweetpotato. The “moist fleshed” potato is sometimes referred to as a “yam” and the “dry-fleshed” as a “sweetpotato.” They are, however, both sweetpotatoes.

California sweetpotatoe growers produce both types. The varieties called Hannah and Golden Sweet (sometimes also called Hanna Gold are the main” dry-fleshed” types grown. They have cream colored outer layer skin with yellow interior flesh.
The major “moist-flesh” or “yam” type varieties include the Garnet, Diane, and , Beauregard. The Garnet has dark-red, smooth skin with orange flesh. It is considered the premium yam type sweetpotato because of its excellent flavor. There are other red-skinned varieties that are not Garnets. The beauregard has copper colored skin with deep orange flesh. It is the most commonly grown variety in all states.

A growing part of the industry now includes oriental, or more commonly, Japanese yams. These may have a variety of flesh and skin colors, including white, purple, and red, but are typically dryer than a Beauregard, with more subtle flavor.
Where did the term “yam” come from? A true yam is an underground tuber. It may vary in the size range of a white potato to enormous yams weighing 30-40 pounds and measuring as much as 3 feet in length.

The sweetpotato is native to Peru and Central America and some South Pacific islands. The yam is more specific to Africa. The word “yam” comes from the African word “nyami.”

It is said that the word “yam” was used for sweetpotatoes a long time ago by the People in the southern United States because of their similarity to true yams. As time went on, the state of Louisiana picked up the term “yam” and used it in the advertising of their sweetpotatoes, in order to distinguish theirs from the sweetpotatoes grown in the northeastern states. Now , the term “ yam” is marked terminology to denote a moist fleshed sweet potato after is cooked or baked.

Sweetpotatoes are native to tropical America, where it is cultured as a perennial. Columbus found the sweetpotato being eaten by the natives of the West Indies and brought it back to Europe about 1500. It was not until some years later that the “Irish” or “white potato” was found in the mountains of Peru.

Sweetpotatoes are one of the most important carbohydrate crops in the world in developing countries. There are about 90,000 acres of sweetpotatoes grown in the United States, with most of these being grown in Louisiana, Mississippi, and North Carolina. California ranks forth in are planted to sweetpotatoes (about 10,000 acres), and third in total production (about 4.5 million 40 lb boxes) after North Carolina and Louisiana. About 80% of the California productions is located in Merced County. Sweetpotatoes are harvested in the late summer through fall, and are packed and stored for sale through the year.