This monograph is a fine example of the thorough work we may expect from Wageningen in general, from its author in special. What present-day botanist gets the opportunity to study the material of his group from about a hundred herbaria all over the world and more than half the number of species in nature! Each species gets: nomenclature, typification and literature; an extensive description about 1 page long; short paragraphs on Distribution and Ecology; a citation of (part of) the specimens studied, including the precise locality and the herbaria; sometimes one or a few note(s); full-page drawing and map.