The trunk represents the Atlantic ocean; limbs represent seas; leaves
represent river basins.
Put the pointer on the map; when the pointer becomes a hand (along
the northern Mediterranean), click to see associated real-world map views
made from files from the Digital Chart of the World.
This map first appeared, in a variation, in Essays on Mathematical Geography (by the author of this article), Monograph #3, Institute of Mathematical Geography, 1986. Another variation of it will appear in the forthcoming eBook, Graph Theory and Geography: An Interactive View, Sandra L. Arlinghaus, William C. Arlinghaus, and Frank Harary, New York: John Wiley and Sons, 2001.