South Africa boasts a wealth of Pelargonium species including those in the section "Hoarea", geophytes with some of the most unusual and spectacular flowers in the genus. This study describes 26 species of Hoareas in detail. It discusses their ecology and cultivation, with special attention paid to the effect of droughts, fire and habitat alteration on the lives of these plants. Hoareas are the least studied of the Pelargoniums. Some of them remained undescribed until the 1990s and little or no research has been published on the ecology of Hoareas. Geophytic Pelargoniums is the culmination of over ten years of field observations by the author and includes his work on the cultivation of most of these species. The impact of human activities on Hoarea populations is examined and a detailed discussion of the factors determining the conservation status of these plants is included. Many Hoareas have beautiful foliage and flowers, and are perfect for ornamental horticulture. Most are best propagated from seed. Drawing on his wealth of experience, the author discusses in depth the cultivation of each species. The beauty of these Pelargoniums makes them outstanding subjects for fine botanical illustration and the illustrator's attractive and meticulous pen-and-ink drawings bring the text to life. Many of the Hoareas are featured in leaf and in flower, and the development of various species from seedlings to young plants in illustrated. In addition, twelve paintings by the artist are reproduced in full colour.