Fruit refers to the fruit of a plant that can be eaten directly. These plants are called fruit trees. Fruits generally contain more soluble sugars, and many also contain volatile aromatic substances. The nucleolus of the common fruit is inedible. For example, the nucleolus of apricot, peach, plum, and medlar contains toxins. The seed, flower bud or bark of apple, cherry, plum, plum, and pear Rosaceae also contain toxicity.