Praeger's classic 1932 work provides a systematic description of the Sempervivum-group (Crassulaceae) in order to resolve the confused state of Sempervivum in our gardens and horticultural books.

Sempervivums (Hauswurz, houseleeks, liveforever, hen and chicks) found in gardens are often hybrids. They occur from the Canary Islands to Great Britain to the Himalaya.

Where species are so variable and hybridization is so rampant as in the Sempervivum-Group, only prolonged field-work and cultivation will lead to reliable results. In the present instance, by growing all the plants for at least several years under similar and uniform conditions, and observing them at all seasons, the author presents an account of the group in which, he hopes, error has been reduced to a minimum.

The first part of the book provides a general introduction to systematics, history, variability, hybrids, parasites, epiphytes, teratology, cultivation, economics and hardy Sempervivums in gardens.
The systematic second part provides descriptions and illustrations of Sempervivum, Aichryson, Aeonium, Greenovia and Monanthes of the Sempervivum-Group.

An addendum with garden names and an index with species and synonym names complete the volume.