The number comes from a simple game of trees—meaning the charts used in graph theory. In this game, you make a forest of trees using seeds. In other words, you make as many tree graphs as you ...

They used a tree-shaped graph called the Yule tree, first developed in 1924 by G. U. Yule to map genealogical history. "The full history of the evolutionary process of a given species can be ...

They used a tree-shaped graph called the Yule tree, first developed in 1924 by G. U. Yule to map genealogical history. “The full history of the evolutionary process of a given species can be neatly ...

When a Yule tree is not a yule tree: in 1924, G. U. Yule created a graph to map genealogical history. At this time of year, the words “Yule tree” may conjure images of brightly decorated balsam firs.