TALK GIVEN at the MELVILLE KOPPIES AGM
ALLAN ABEL - 19TH AUGUST 2006.
What is an Orchid?
Orchids are evolutionary very advanced plants belonging to the order Orchidaceae, which is one of the
largest orders of flowering plants. There are approximately 25 000 described species and many more
awaiting either scientific description or discovery. They can be found in almost every ecological habitat, with
the exception of areas of permanent ice or extreme desert, and they do not grow underwater. They are
found on all the continents except for Antarctica, but are particularly numerous in northern South American
and south-east Asia.
The plants and blooms come in a bewildering variety of shapes, sizes and colours. Orchid plants vary from
miniatures species which can fit in a sewing thimble (Notlyia mirabilis) to those weighing a tonne or more
(Grammatophyllum speciosum).The flowers also exhibit tremendous variation in size with those of
Angraecum pusillum (a Southern African species) only 5mm in diameter, whilst Phragmipedium caudatum
has pendant petals that can reach a length of 700mm.
Orchids can be either epiphytic (growing on trees), lithophytic (growing on rocks), terrestrial (growing on the
ground) or, rarely, saphrophytic (growing in a symbiotic relationship with a fungus in the soil). It must be
emphasised that epiphytic orchids are not parasites. They have evolved to take advantage of the favourable
growing conditions that are available in the forest canopy than is available on the dark forest floors.
How to recognise an orchid flower?
For the layman, there are several characteristics of an orchid flower which are helpful in identifying the
flower as belonging to an orchid species.
1. The flower comprises 2 whorls of 3 parts each – 3 outer sepals and 3 inner petals. The one petal is
usually very different in shape, colour and marking from the other petals, and is know as the
labellum or lip. The function of the lip is to attract and direct pollinators to the pollinia.
2. When the flowers are flattened, they can be divided into mirror halves only vertically and not
horizontally.
3. The most distinctive characteristic are the sexual parts of an orchid flower. The separate pistils and
stamens have combined into a single structure known as the gynostemium or column. The pollinia
(pollen masses) are usually located near the tip of the column under an anther cap. The stigmatic
surface can be located anywhere on the column, but often just below the anther cap. The pollen is
united into masses called pollinia, usually in two or four pairs. The pollinia are not powdery but
range from jelly-like to hard masses.
Orchids of Southern Africa
There are currently 466 orchid species in 52 genera to be found in the area south of the Cunene and
Limpopo rivers. Of these, 302 (65%) are endemic, which means they are found here and nowhere else in
the world. Eight species have only been recorded only once and five species have become extinct (3 Disa
and 2 Holothrix species).
Gauteng has only 52 recorded species belonging to 12 genera. The largest genera are Eulophia (15
species) and Habenaria (14 species), and the vast majority are terrestrial species.
The following species are found in the Melville Koppies Nature Reserve.
Bonatea porrecta
Size:
Leaves:
Flowering season:
Distribution:
Habitat:
up to 65cm.
withered and dry at flowering.
June – August.
from Eastern Cape to Limpopo, Botswana and Mozambique.
Bonatea speciosa var. antennifera
Size:
Leaves:
Flowering season:
Distribution:
Habitat:
up to 100cm
leaves fully developed at flowering.
March - April
Northern South Africa, Botswana, Zimbabwe & Mozambique
Grasslands, often under trees and shrubs
Eulophia clavicornis
var clavicornis (pale lavender lip)
var inequalis (yellow lip)
Size:
Leaves:
Flowering season:
Distribution:
Habitat:
up to 30cms
just beginning to shoot at flowering
August – December
eastern South Africa from Port Elizabeth to Kruger.
grassland often in rocky and well-drained areas.
Eulophia ovalis ssp. bainsii
Size:
Leaves:
Flowering season:
Distribution:
Habitat:
up to 65cm.
leaves 50%-100% developed at flowering.
December – January.
Widespread from eastern Free State to tropical East Africa.
grassland or stony thornveld, in dry to seasonally marshy areas.
Eulophia welwitschii
Size:
Leaves:
Flowering season:
Distribution:
Habitat:
up to 90cm
leaves partially or fully developed at flowering.
November – January.
northern-eastern South Africa and widespread in tropical Africa.
grassland in dry to seasonally marshy areas.
Habenaria barbertonii
Size:
Leaves:
Flowering season:
Distribution:
Habitat:
up to 40cm
about 10, regularly arranged (cauline) on the stem and fully developed at flowering.
February – March.
Gauteng and Mpumalanga.
rocky hillsides from 1000 - 1500 meters in altitude.
Habenaria filicornis (syn chlorolitica)
Size:
Leaves:
Flowering season:
Distribution:
Habitat:
up to 60cm
few, regularly arranged (cauline) on the stem and fully developed at flowering.
February – March.
northern South Africa, Botswana and tropical Africa.
seasonally damp or marshy grasslands.
Habenaria dreggeana
Size:
Leaves:
Flowering season:
Distribution:
Habitat:
up to 40cm
two basal leaves, pressed against the ground.
January – April.
eastern South Africa, Zimbabwe, Angola, Zaire & Uganda.
grassy slopes from 300m to 2000m in altitude.
Habenaria epipactidea
Size:
Leaves:
Flowering season:
Distribution:
Habitat:
up to 60cm
stem is densely leafy.
January - March
eastern South Africa, Zimbabwe, Angola and East Africa.
Holothrix randii
Size:
Leaves:
Flowering season:
Distribution:
Habitat
NB:
up to 40cm
two basal, dormant at flowering
September - December
northern South Africa, Zimbabwe, Tanzania
grassy slopes and rocky ledges
On the Endangered Species list!