This book summarizes in a rather popular way scattered information on the problem of conservation of plant diversity. Ordered to the eight major regions of the world, a rather arbitrary selection of about 2000 rare and endangered species are described, some 250 also illustrated, partly in colour. The commission on endangered plant species under the IUCN has estimated that c. 20,000 species of higher plants need protection, whereas they include only 250 species in the Red data book of plants. This illustrates the very much incomplete knowledge of the current conservation status of plant species. Therefore, any attempt to summarize the present state of knowledge is unavoidably rather erratic.