A plum is a low-calorie fruit that contains vitamins, minerals and amino acids. There are more than 140 kinds of plums that may be small in size or slightly larger and different in color.
One plum contains 30 calories, and a half-cup of cut-up plums has 40 calories. A plum contains calcium, potassium, copper, zinc and vitamins A, C and K. Because a plum has a pit, it is also called a drupe. Plums that are used to make prunes are yellow inside and contain a freestone pit, which sits loosely inside the plum.
Plums can be yellow, red, dark red, blue or purple. The flesh inside of some plums is succulent, but certain kinds of plums are not as juicy. The inside of a plum is yellow or red. Some plums have a sweet taste, while others are tart.
Varieties of plums include Japanese, European, Santa Rosa, red beaut and elephant heart, which is a large plum that is red inside. Elephant heart plums are favored for cooking. Smaller plums are European plums, which are not as juicy as Japanese plums. European plums are blue or purple on the outside and yellow on the inside. European, Italian, president, empress, Stanley and tragedy plums are used to make prunes.