Plants with perianths (calyx and corolla), stamens and pistils, and producing fruit are called flowering plans (angiosperms). In the systematic sections around 1400 plants are cultivated in order to present the great variety of the roughly 250,000 known species of flowering plants. The grounds consist of a great number of flowerbeds with the purpose of showing how plants are related to each other. Those closely related are standing together, such as all in the buttercup family (Ranunculaceae), so that visitors are able to see that anemones, buttercups, clematis and meadow rues are all members of this family.
You may come at any time during the growing season and find flowering plants in the systematic sections.