Scientists look at the evolutionary history of organisms to divide them into kingdoms. For awhile, there has been 5 kingdoms, but many scientist are now using 6 kingdoms.

This site is a description of the history behind the 5 Kingdom system suggested by Robert Whittaker. An extensive list of resources is included.

College-level instructor's notes describing taxonomy. Explanations and images give a chronological history of the science of classifying organisms.

Explore the world of plants and all that encompasses the second biggest kingdom of classification.