You may think that if you sow a sweet persimmon seed it will produce the same sweet persimmon.
In reality, if you sow a sweet persimmon seed, it produces wild persimmons. If you sow an apple seed, the apples produced are very small; if you sow a pear seed, wild pears are produced. Most fruits we eat are grafted and improved varieties.
In grafting, the plant that is selected for its root is called the stock or rootstock. Rootstocks are selected from wild varieties because they are vigorous; however, their fruit is small and tasteless. That is why improved fruit varieties are grafted into rootstocks. Then, why is it that the seeds of the improved fruit varieties still produce wild species?
It is because the fruits we eat are actually ripened ovaries coming from one or more flowers, while the ovules in the ovaries still pass down the characteristics of the rootstocks. Even though the outer appearance changes, the seeds in it remain unchanged.