This paper presents the results of interviews and a questionnaire study on public knowledge of the concept
of biodiversity and of plant species richness in Switzerland. Despite its extensive use in science and policy making, the concept of biodiversity is not widely recognized or known to people in Switzerland. Overall, 60% of all study (161 grammar school pupils, 110 non-graduates,
and 96 graduates in the Canton of Zurich) had never heard the term biodiversity, while the others had come across it primarily in the media. Few study participants considered their school education a relevant source of information about biodiversity. Study participants most frequently referred to the diversity of plants and animals when defining biodiversity, but also quite often believed that biodiversity had something to do with ecological concepts such as the equilibrium between all components of nature. Both young people and adults held widely inaccurate ideas of the plant species richness of communities. Particularly for Switzerland, plant species richness was strongly overestimated.