To simplify things a little bit botanical names always consist of a genus and a specie name sometimes added with a sub-specie name; for example Acacia sieberani woodii (paperbark tree).
But genera (plurial of ‘genus) belong to a family. The succulent family Cactaceae is composed of about 100 genera with around 2000 different species.
Example: Cactaceae (family); Ferocactus (genus) acanthodes (specie).
Other succulents are botanically divided in approximately 50 families with over 600 genera and an estimated 15000 natural species (except cultivars and hybrids) of which around 10,000 are native to Southern Africa including Madagascar.
Other parts of the African continent with a significant number of native succulents are South Morocco and the isle of Socrota. The Canary Islands, India and Australia also have a number of ‘indigenous’ succulents. In Europe one can find the endemic areas of some sedum- and sempervivum species.
The America’s are home to the Cactaceae (except for one genus; Rhipsalis); and Agavaceae (a.o. genera Agave and Yucca) originating to a wide diversity of local environments within a stretch of 10,000 kilometres; altitudes ranging up to 4000 metres; climates with temperatures ranging from -18 degrees Celsius to +45 degrees Celsius; from dry rocky deserts to foggy deserts and (sub-)tropical rainforests and from fertile soils to soils with a high salt content. More or less the same diversity applies to succulents from other parts of the world.
Despite their different backgrounds it is very well possible to let a wide variety of succulents, including cacti, live harmoniously together in one garden provided that the involved gardener can organise (by simulation) some measurements/precautions in which certain plants will adept to their new environment.
In the description of the different families, genera and (where applicable) species we will indicate these measurements in the future.
In general it’s always worthwhile to find your way in the endemic habitat of plants in regards to soil structure/contents, local climate and local ecological aspects such as the nature of other plants.
A plant has, in its natural habitat, always a reason to grow just there. Not only humans are smart!