There is a graphical tree.
If you're looking a the FAMILY view listing parents and children, touch on INFO at the bottom left corner. Then roll to the top of the individual's page, if necessary, to see his/her name and picture. Under his/her name and to the right of his/her picture, touch VIEW IN TREE, and that will flip the page to the tree.
It's easier to use the tree if you turn your iPod or iPhone to landscape view. Then you can slide left or right and up or down as needed to maneuver through the tree. Or click on the MAGNIFYING GLASS at the bottom right corner to bring up the index so you can choose a specific person to view in the tree.
To get back the list of INFO, FAMILY, PHOTOS, and EVIDENCE (sources) from the tree view, click on the person's NAME or on the SILHOUETTE OF A PERSON'S HEAD AND SHOULDERS ICON at the bottom left corner.