The Cape Fynbos is a wonder of the world. The Cape Floral Kingdom contains 526 of the world’s 740 erica species, 96 out of the world’s 160 gladiolus species and 69 proteas out of 112 on earth.
Fynbos can be defined as a shrubland with an unusual mixture of plant types of different shapes and sizes that have been termed, “growth forms”. There are four of these growth forms; the proteoids – tall protea shrubs with large leaves; the ericoids – heath-like shrubs; reed-like plants – the restoids; and bulbous herbs – the geophytes.
The tallest shrubs in fynbos are the proteoids they are 1 to 3 metres in height and have large, leathery leaves. They include the Aulas, Leucadendron, Leucospermum, Mimetes, Orothamnus, Paranomus, Protea and Vexatorella species.
Proteoids encompass a wide range of shrub shapes and floral forms. Of all the fynbos groups, the proteoids have been most extensively studied as they are conspicuous and as cut flowers, have tremendous economic potential
The heath-like ericoid growth form comprises about 3 000 species, including the family Ericaceae and many of the largest fynbos genera such as Aspalathus, Agathosma, Cliffortia, Muraltia and Phylica. The leaves of ericoids are small and mostly hard and the edges rolled under. With one of two exceptions, the ericoids store their seeds in the soil.
The restoids comprise all 310 species in the Restionaceae, a family closely related to the grasses. Large genera in the Restionaceae include Elegia, Ischyrolepis, Restio and Thamnochortus. Restoids comprise the growth form, which uniquely characterises fynbos. All members of the restoids have separate male and female plants. The seeds of many of the plants are dispersed by ants.
The final group is the geophytes with 1 400 species. Fynbos has the richest geophyte flora in the world. Some of the larger genera are the irid Gladiolus, the lily Lachenalia and the orchid Disa.
The geophytes appear only in the wetter months – they are less visible in the dry summer months when the leaves die back.
Because fynbos soil is rather infertile, nutrients to survive are very scarce. Plants need to be very efficient in locating and absorbing those that are available and use them to their best advantage. Specialised nutrient-uptake mechanisms have evolved in many fynbos plants and others have formed symbiotic partnerships with bacteria and fungi.
Bacteria stimulate the production of nodule outgrowths on the roots of certain species, which enables the host plant to absorb nitrogen that would otherwise be unavailable. It also stimulates the production of dense rootlets to improve the uptake of ions.
An unusual way for a plant of coping with nutrient poverty is carnivory. The sundews trap and digest insects by way of sticky glandular hairs on their leaves. Fynbos also has about a hundred species of root parasites, which derive their nutrients from the roots of other species.
Some fynbos plants have a pungent smell, which evolved to discourage herbivores. The leaves of the blister bush, on the other hand, contain a substance that causes blisters on the skin of people who brush past it, also to deter herbivores.
Fynbos plants balance their water content when soil moisture is low by conserving energy, much like the human inhabitants of Mediterranean climates. They metabolise energetically in the early morning, rest through the hot midday and resume activity in the late afternoon.
Fynbos plants also have variations in their rooting systems to cope with drought. Some have long taproots that grow to great depths and others have shallow, fibrous roots that capture whatever water there is near the soil surface. In this way they can coexist within a small area without competing with each other for water.
The leaves of fynbos plants have characteristics that enable them to cope with excessive solar radiation. Some have epidermal hairs that increase the sheen of the leaf, thereby making it more reflective.
There is no doubt that the Cape fynbos although small and fragile, is a very valuable natural heritage.