You can see this on the BBC Four Botany: A Blooming History for a clear picture when using with students.

This video clip from the BBC (from the TV series Botany: A Blooming History) introduces the ideas underpinning classification, through the work of Carl Linnaeus.

Carl Linneaus attended Uppsala University as a medical student. He became very interested in the forms and variety seen in plant reproductive organs, the stamens (male parts) and pistils (female parts). He discovered that different species had different ratios of stamens to pistils. After 5 years of research, he published the first book of systematic plant classification, the "Systema Naturae" (published in 1735). This small book divides the plant kingdom according to the number of stamens present, then the number of pistils present in the flowers of a plant. This is a significant book in the history of science and of plant classification since it establishes relationships and a basis for naming plants according to their physical attributes.

An introduction to the ideas underpinning classification. The emphasis is upon using observations in order to group organisms. It can be replicated in the classroom using flowers, shells, leaves etc.as an introduction to the making and using of keys. It can also be an introduction to plant anatomy. Students could be given flowers to look at, from which they can dissect out the male and female parts. It is also useful as an aspect of "How science works". Students could watch this and then the ideas of "observations leading to hypotheses which can be tested" can be discussed. This is relevant, since this mechanism of classification has since been discredited by the work of later botanists and geneticists.