The phrase per stirpes seems to appear in almost every will ever written and has provoked countless questions about its meaning.
Literally, the term means “by the roots.” A better understanding of the term can be gained by contrasting it with the term per capita.
If you leave your property to your issue (lineal descendants) per capita, it means that you are leaving your property to all of your living descendants, whether children, grandchildren or great grandchildren, each receiving an equal share.
If, however, you leave your property to your issue per stirpes, your property would be divided into a number of shares equal to the number of your children, including any of your deceased children leaving issue. Each living child receives a share, and the children of any deceased child would divide their deceased parent’s share equally.
— Kevin Palmer