Botanical diversity is under high pressure in densily populated countries and protected areas play a very important role in species conservation. In the Netherlands, borders of most nature reserves, including Natura 2000 sites, have been drawn on the map before the 1990s. In the 1990s, long-term projects to collect observation data of botanical diversity had just started to intensify among a community of volunteers united in FLORON Plant Conservation Netherlands, Dutch Mycological Society and the Bryological and Lichenological Society. Observation databases increased to around 40 million records in 2019. Defining Important Plant Areas is a proven method encouraged by the Global Strategy for Plant Conservation of the Convention for Biological Diversity and by IUCN’s Key Biodiversity Areas program. This report gives an overview of botanical biodiversity hotspots, regardless of their current nature conservation status, also providing insights of plant diversity of urban and rural areas in The Netherlands.