This is, as the name suggests a monograph of the genus. More than 240 colour photographs of flowers, flower part and some of habitat and plants in situ. 80 reproductions of original coloured drawings from the early Herbaria and publications such as Lindenia and Reichenbachia with some line drawings. This is typical of the high quality that we have come to expect from an author of Rudolph Jenny's calibre. 58 species and 6 natural hybrids are listed in detail.