In situations where one is restricted to using plain text, it is often easier to show a person's ancestry using an Ahnentafel rather than a tree.
For a particularly complex example of a family tree, see Family Tree of the Greek Gods or Family Tree of the Royal Family.
A family tree is also the name given to an apple tree where several different varieties of apples have been grafted on to the same root-stock. This has a number of advantages, in enabling pollination between the different varieties, and in spreading out fruit production as the different varieties mature at different times.