SA Orchids: Epiphytic Orchids
In
the warmer and more humid parts of South Africa there are a number of epiphytic
orchids, which thrive on trunks and branches of trees and bushes. Unlike
tropical Asian and American epiphytic orchids, which have often large and
showy flowers (e.g. Cattleya or Cymbidium, that we see in
our florist shops), the flowers of most South African epiphytic orchids
are small and inconspicuous. When searching for our indigenous epiphytic
orchids it is sometimes a good idea to look out for their long, whitish
roots creeping over the bark as these are often more noticeable than the
rest of the plants. The leaves and stems are also not very noticeable, and
leaves are even absent in a few species.
Where exactly do they occur?
South African epiphytic orchids are found in the southern coastal
areas of the Western Cape, in the Eastern Cape and in KwaZulu-Natal, as
well as in the inland areas of Mpumalanga and Northern Province. In the
Western Cape, epiphytic orchids occur only from Swellendam eastwards:
there are no epiphytic orchids near Cape Town. There are also no epiphytic
orchids in the whole of the arid and semi-arid Karoo.
In which habitats do we find them?
Epiphytic orchids are found in a variety of forested habitats, ranging
from hot subtropical lowland forest to cool high-altitude mist forest,
frequently near the banks of rivers and streams. Epiphytic orchids are
also found in hot and relatively dry scrubland and thorn-bush, and some
species have even be found as epiphytes on succulent tree-like euphorbias!
Occasionally, epiphytic orchids are also found growing epilithically on
rocks.
The South African epiphytic orchid flora and where it comes from
Most of the South African epiphytic orchids belong to genera which are
primarily tropical African in distribution, but range into our region
with one or few species. Exceptions are the two primarily Asian genera
Acampe and Oberonia, the pantropical genus Bulbophyllum
as well as Mystacidium (see below). In total there are 56 epiphytic
orchid species in 18 genera in South Africa. This represents 12% of the
total orchid flora of the region. Among these epiphytic orchids Angraecum
(6 species), Mystacidium (7) and Polystachya (11) are represented
comparatively well with more than five species. Mystacidium is
the only epiphytic genus which is primarily southern African as most of
its species and the highest diversity are found here. There is not a single
genus endemic to our region.
How to grow South African epiphytic orchids
Epiphytic orchids are normally easier to cultivate than terrestrial
orchids and are therefore more popular as garden plants. To find out more
about temperature, shading and watering requirements it is a good idea
to look at the natural growing conditions of the plants. Epiphytic orchids
can be grown in pots or hanging-baskets in a loose and well-drained substrate
such as bark chips with some polystyrene granules added. Ordinary garden
soil will quickly lead to the plants rotting. Plants can also be successfully
grown by mounting them on slabs of cork oak or on the bark of living garden
trees. In the growing season in summer the plants must be frequently watered,
although the substrate must never be permanently wet (this is why plants
mounted on bark normally do so well). Much less watering is needed in
the dormant season in winter. Adequate air movement is necessary throughout
the year.
It is highly illegal to take orchids from the wild, but epiphytic orchids
can easily be obtained from specialist orchid nurseries - contact your
local orchid society for their addresses. The easy-to-grow and also attractive
Ansellia africana needs a hot place in your garden, with little
shading. Aerangis, Angraecum, Cyrtorchis, Mystacidium and Polystachya
are also good choices to start with, and require somewhat cooler and shaded
sites.
February 2001
