appearance colored colors coloured colours compare comparison cooking culinary cultivars dicotyledonous edible enormous food gigantic golden-sweet-potato healthy herbaceous-perennial-vine ipomoea-batatas kūmara kūmera large nutritional nutritious plant popular purple raw root root-vegetable shape shapes size Sizes skin-colours skins starchy surface surfaces sweet-potato sweet-potatoes texture textures tuber tuberous uncooked varieties vegetable vine