The sweet potato or kumara (Ipomoea batatas) is a dicotyledonous plant that belongs to the family Convolvulaceae.
Its large, starchy, sweet-tasting, tuberous roots are a root vegetable. The young leaves and shoots are sometimes eaten as greens. Ipomoea batatas is native to the tropical regions in the Americas. Of the approximately 50 genera and more than 1,000 species of Convolvulaceae, I. batatas is the only crop plant of major importance—some others are used locally (e.g. I. aquatica (kangkong)), but many are poisonous. The sweet potato is only distantly related to the potato (Solanum tuberosum) and does not belong to the nightshade family.
—Sweet potato from Wikipedia, the free encyclopedia
There are many different types of the sweet potatoes. Different countries grow different varieties. There are four types sweet potatoes grow in Australia.  WSPF (white skin, purple flesh) type looks different from Okinawan purple sweet potato
|||Consumer Information from Australian Sweetpotato Growers Inc|