SA Orchids: Pterygodium
Pterygodium
is a small African genus, represented by 19 species in southern Africa and
one in Tanzania. The plants are slender herbs with small to medium-sized
flowers, and are often hard to recognize as orchids. They are found in a
variety of different habitats, ranging from fynbos and bushveld to grassland.
Some species are very common and easy to find, but others are known only
from one or few sites and are rare even there. Most grow in small to large
colonies. A mass display of P. acutifolium with hundreds or thousands
of plants can often be seen in mountain marshes after fire, and P. alatum
is normally found in dense clusters of countless individuals. Some species
are known for their rather unpleasant odour, which can be quite strong.
Pollination is by oil-collecting bees. Flowering occurs in spring or summer,
with some species flowering mainly after fire.
Description
The plants grow terrestrially and have underground root tubers. Most species are less than 50 cm tall, but P. magnum has erect stems of up to 1.5 m length and is thus our tallest orchid. Leaves are lanceolate (lance-shaped) and borne all along the stem; they vary in number from one to many. Inflorescences are terminal and are laxly or densely one- to many-flowered. The small or medium-sized flowers are borne on unbranched spikes, with their colour ranging from yellow to green and white, and sometimes with a purple or maroon flush. While flowers of most species are resupinate (lip facing down), there are also two species with non-resupinate flowers. Flowers are generally open and cup-like which is an important difference to the otherwise very similar and closely related genus Corycium. The small and normally narrow lip is linear to deltate and has an elongate appendage. In structure the column is very complicated, with the two anther thecae (pollen sacs) separated and situated on the corners of an elongate horseshoe-shaped connecting part, and the two stigma pads on the median carpel.
Cultivation
Plants of the genus Pterygodium are difficult to obtain and to grow. Cultivation requirements are similar to those for Satyrium.
Selected species and their main distribution
Winter-rainfall area: P. volucris, P. catholicum ('moederkappie',
'mammakappie'), P. caffrum, P. alatum ('vlerkies'), P. acutifolium,
P. hallii, P. platypetalum
Summer-rainfall area: P. magnum, P. cleistogamum (' blind orchid'), P. hastatum, P. cooperi
Click images to enlarge
 P. catholicum |
 P. acutifolium |
 P. alatum |
 P. cooperi |
 P. hallii |
 P. platypetalum |
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 P. volucris |
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Description and images: Hubert Kurzweil
Cultivation: Hildegard Crous
October 2000
(Updated by Clare Archer, August 2010)
