In Dutch forests the species density of vascular plants ranges from I to 61 species per 300 m2. The vascular plant species density is high in the coastal dunes, southern Limburg, river valleys, and fen areas. With the exception of southern Limburg, these areas constitute the Holocene part of the Netherlands. Low species densities occur in the sandy centre of the country. To a large extent, the areas of high species density of vascular plants follow the main river valleys. The bryophyte species densities range from 0 to 21 species per 300 m2. High bryophyte species densities occur mainly in the sandy centre and in the north-eastern part of the Netherlands. The highest species densities occur in fen woodlands and derelict coppices. Bryophyte species density is low in the coastal dunes and the very young woodlands in the recently reclaimed areas (polders). The species density contour maps of vascular plants and bryophytes in the Netherlands have little in common.