The origin of plant taxonomy goes back centuries, and there are thought-provoking parallels between folk classifications and those produced in more recent times. The Swedish botanist Carolus Linnaeus (1707-1778) provided the first widely used framework, the basis of our current classification. He placed all plants in a genus and species, giving each a binomial (such as Taraxacum officinale for the dandelion), allowing botanists worldwide to communicate.

Linnaeus was not very successful in recognizing larger groupings of plants, but in 1786 Antoine-Laurent de Jussieu put all genera in families. Jussieu believed that nature could be represented as a single, continuous series of relationships, and he made his families (and genera) of convenient sizes. There was much debate during the ensuing century and a half as to whether all characters should be used in classification or only in the most important ones. The issue was never resolved...