Cape Floral Kingdom

The world has about 250 000 species of plants ( excluding all the Algae, Fungi and Mosses. Ferns are usually excluded too, but many people include the conifers with the flowering plants) The Cape Floral Kingdom has more than 8 000spp i.e. about 1/3 of the total southern African species, 1/30 of the worlds' species. This shows that the Cape does not have more species than anywhere else, but because the Cape Floral Kingdom covers a small area, when you express the number of species as "per square kilometer" you get a very high figure.

Area
The CFK extends roughly from the mouth of the Orange River to Humansdorp (almost Port Elizabeth). It includes all the Fynbos areas, the succulent Karoo (Namaqualand, Little Karoo, but not the Great Karoo), and the Knysna forests. Fynbos families like Ericaceae and Proteaceae grow along the tops of the mountains right up into tropical Africa - does this mean that fynbos used to cover all that area? Or just that the mountain tops offered suitable habitats? Plants don't know that we have made these boundaries, so they will grow where they can, if their seeds can get there. This means that some species will grow on both sides of the "boundary",i.e. some families will have genera on both sides.

History:
Since the first collectors in the 1600's sent plant specimens back to Europe, the Cape plants have been recognised as being very "different". Exploring and discovering the flora continues as an exciting challenge and new species are still being discovered e.g. Mimetes chrysanthus at Gamkaberg in the 1980's. A new Leucadendron was identified in 2002 at the final get-together of the Protea Atlas Project and Erica species were discovered near de Rust by Yvette van Wyk and Di Turner.

Characteristics:
The family with the largest number of species (1035) in the Cape flora is the Asteraceae (daisies), but because there are lots of daisies in all the other floral kingdoms too, this is not particularly significant. The families which are very significant, because there are not many of them elsewhere, and because they make up a big proportion of the "biomass", are: Proteaceae, Ericaceae, and Restionaceae.

• Restionaceae, Cape reeds.
  There are 294 species, of which 132 are endemic to the Cape Floral Kingdom.
• Ericaceae:
  658 species of which 636 are endemic to the CFK. This is rather a peculiar situation because all these species are in the same genus - Erica. It seems that in this genus the gene pools became isolated quite easily - many have their seeds distributed by ants which don't carry them as far as birds or wind might - and they developed into separate species.
• Proteaceae:
  330 spp of which 319 are endemic to CFK.

Forest biome:
Our forests are examples of Afro-montane forest which occurs in large or small patches all the way up the eastern escarpment into tropical Africa. The forest which is most species -rich is in Madagascar. Further south there are fewer species. There are few endemics and the forest does not seem to have evolved in response to the same pressures as the other Cape plants have.

The Cape flora seems to have evolved in response to winter rainfall and hot dry summers. This presents particular problems to plants in terms of their metabolism. Most metabolic processes increase with temperature (within reason), but the lack of water in the warm summer means that the plants shut down their activities and become almost dormant. The converse of this problem is that when water is available in the winter, the temperatures are low and metabolism is relatively slow.

It seems that adapting to this problem is what has made the Cape flora so different. The main growth form is short woody shrubs, usually with small (or in the succulent Karoo, succulent leaves). There are very few annuals, ( even Namaqualand has far fewer annuals than deserts usually have.) presumably because annuals usually grow and flower in a summer season.
Our Botanical Garden cultivates southern Cape plants, including the area inland past the Swartberg; as well as eastward to include the Knysna forests. This means that it is a useful place to demonstrate aspects of the Cape Floral Kingdom