Mr. C. Sipkes is one of the pioneers of the so-called ‘heemtuinen’ or wildlife gardens. These gardens, and especially the nature gardens (i.e. habitat creation followed by a – for the greater part – spontaneous vegetation development) are important in several respects: 1. education concerning nature and environment; 2. species conservation and 3. research on the ecology of individual plant species and vegetation types and on habitat creation. The growing interest in the wild flora and the increasing application of native species in gardening has led to a falsification of the flora in the Netherlands. As a result, the phytogeographical research is threatened. Evidence from observations in several ‘garden’ situations, neighbouring on more or less suitable habitats, shows that probably intentional seeding and planting in natural areas play a greater part in this flora falsification that spontaneous escapes from such gardens. Only very few species appear to have escaped. Directives should be given, e.g. through firms dealing with seed supplies, for the proper application of seed mixtures of wild species in order to prevent further flora falsification.