Silver trees (Leucadendron argenteum) only occur naturally on the granite and clay soils of the Cape Peninsula, surrounding Table Mountain and the Back Table. A few tiny patches, possibly planted there early in the Cape Colony’s history, occur near Stellenbosch, Paarl and Somerset West.
The Disa uniflora, also known as the Pride of Table Mountain is a showy orchid that blooms under waterfalls, along streamlets and seeps on the top and upper slopes of Table Mountain and the Back Table, in January–March.
Table Mountain and the Back Table have an unusually rich biodiversity. Its vegetation consists predominantly of several different types of the unique and rich Cape Fynbos. The main vegetation type is endangered Peninsula Sandstone Fynbos, but critically endangered Peninsula Granite Fynbos, Peninsula Shale Renosterveld and Afromontane forest occur in smaller portions on the mountain.
Table Mountain’s vegetation types form part of the Cape Floral Region protected areas. These protected areas are a World Heritage Site, and an estimated 2,200 species of plants are confined to Table Mountain range, of which 9000, including a great many types of proteas, are endemic to these mountains and can be found nowhere else.
Of the 2200 species on the Peninsula 1500 occur in the 57 km2area comprising Table Mountain and the Back Table, a number at least a large as all the plant species in the whole of the United Kingdom.
The Disa uniflora, despite its restricted range within the Western Cape, is relatively common in the perennially wet areas (waterfalls, streamlets and seeps) on Table Mountain and the Back Table, but hardly anywhere else on the Cape Peninsula. It is a very showy orchid that blooms from January to March on the Table Mountain Sandstone regions of the mountain. Although they are quite widespread on the Back Table, the best (most certain, and close-up) place to view these beautiful blooms is in the “Aqueduct” off the Smuts Track, halfway between Skeleton Gorge and Maclear’s Beacon.
Remnant patches of indigenous forest persist in the wetter ravines. However, much of the indigenous forest was felled by the early European settlers for fuel for the lime kilns needed during the construction of the Castle. The exact extent of the original forests is unknown, though most of it was probably along the eastern slopes of Devil’s Peak, Table Mountain and the Back Table where names such as Rondebosch, Kirstenbosch, Klassenbosch and Witteboomen survive (in Dutch “bosch” means forest; and “boomen” means trees) . Hout Bay (in Dutch “hout” means wood) was another source of timber and fuel as the name suggests.
In the early 1900s commercial pine plantations were planted on these slopes all the way from the Constantiaberg to the front of Devil’s Peak, and even on top of the mountains, but these have now been largely cleared allowing fynbos to flourish in the regions where the indigenous Afromontane forests have not survived, or never existed.
Fynbos is a fire adapted vegetation, and evidence suggests that in the absence of regular fires all but the drier fynbos would become dominated by trees.
Regular fires have dominated fynbos for at least the past 12 000 years largely as a result of human activity.
In 1495 Vasco da Gama named the South African coastline Terra de Fume because of the smoke he saw from numerous fires.
This was originally probably to maintain a productive stock of edible bulbs (especially watsonians) and to facilitate hunting, and later, after the arrival of pastoralists, to provide fresh grazing after the rains.
Thus the plants that make up fynbos today are those that have been subjected to a variety of fire regimes over a very long period time, and their preservation now requires regular burning.
The frequency of the fires obviously determines precisely which mix of plants will dominate any particular region, but intervals of 10–15 years between fires are considered to promote the proliferation of the larger Protea species, a rare local colony of which, the Aulax umbellata (Family: Proteaceae), was wiped out on the Peninsula by more frequent fires, as have been the silky-haired pincushion, Leucospermum vestitum, the red sugarbush, Protea grandiceps and Burchell’s sugarbush, Protea burchellii, although a stand of a dozen or so plants has recently been “rediscovered” in the saddle between Table Mountain and Devil’s Peak.
Some bulbs may similarly have become extinct as a result a too rapid sequence of fires.
The fires that occur on the mountains today are still largely due to unregulated human activity. Fire frequency is therefore a matter of chance rather than conservation.
Despite intensive conservation efforts the Table Mountain range has the highest concentration of threatened species of any continental area of equivalent size in the world.
The non-urban areas of the Cape Peninsula (mainly on the mountains and mountain slopes) have suffered particularly under a massive onslaught of invasive alien plants for well over a century, with perhaps the worst invader being the cluster pine, partly because it was planted in extensive commercial plantations along the eastern slopes of the mountains, north of Muizenberg.
Considerable efforts have been made to control the rapid spread of these invasive alien trees. Other invasive plants include Black Wattle, Blackwood, Port Jackson and Rooikrans (All Australian members of the Acacia family), as well as several Hakea species and Bramble.