Each species is given a double page. One page presents photographs (with each of the many public sources of colour slides acknowledged), depicting the whole plant, any diagnostic feature of the species, the inflorescence and flowers. The other page describes the species, each in the same way: growth habit, leaves, inflorescence and flowers, the flowering season (generally winter, but sometimes summer), diagnostic features and closely similar species, the range and character of the distribution and habitat, and a map of South Africa, showing National and Provincial borders and with the distribution of each species of Aloe shown as a patch of blue-green. I enjoyed the maps immensely, not only for the geography lesson about South African places that they provided, but, in conjunction with my larger Atlas map of South Africa and the "Guide" text, a quick habitat survey as well. The maps are also helpful because they picture the size and shape of the range of each species (from very large to very small, as would be expected of such a large and diverse genus), whether it is broadly continuous or not (most seem to be), whether species overlap (they appear to, significantly) and the landscape they are part of (coastal sands, lowland bush, dry shrubland, inland grassland, rock outcrops and high altitudes). Are different species that grow together in the same landscape kept apart by habitat, different pollinators, or what?
The species are arranged alphabetically in groups: tree aloes (5 spp), single-stemmed aloes (15 spp; I might have called these "caulescent"), multistemmed aloes (9 spp.), rambling (5 spp), creeping (7 spp), stemless (23 spp), speckled (5 spp), spotted (26 spp), dwarf (6 spp) and grass aloes (24 spp). The authors admit that some of these groups are not natural, in the sense that all the species are closely related, because some merely appear similar, by converging from different evolutionary pathways. The truth is that the identification of aloes is by no means easy in many cases. Some are naturally very variable geographically, individuals of a species vary according to age and condition, there are colour variants and hybridization is common among several species. However, the authors maintain that aloe identification will now be considerably easier. My ability to judge is very limited, but I think their goal has been achieved. For me, though, the main value lies elsewhere.
There are short background sections on aloe-like plants, such as Hawarthia and Kniphofia, medicinal and cosmetic uses (the ancient "aloes" resin, a laxative, and the much more mild Aloe vera gel), conservation (some species are endangered because of over-collecting, and many are naturally very local), and how to propagate aloes and look after them in the garden.
The authors capture an essence about aloes when they describe "The stark beauty of their often strange and inspiring architectures...". They recognise that botanists might want more information about the natural history of the Aloe overall. However, the "Guide" is intended for use primarily for identifying species. It focuses on the question "Which Aloe is that?", and stops sometimes tantalisingly short of the broader picture. The photographs alone achieve most of the story anyway, if you ask the appropriate evolutionary and ecological questions.
Undoubtedly the greatest value for New Zealand readers is the diversity of form, colour and habitat that the photographs and descriptions reveal. There are not many species commonly grown here, and the "Guide" illustrates the wide variety of extremely attractive and interesting plants that we could grow.
