|
Drakaea
(Hammer Orchids)
Named after Miss Drake, a botanical artist who drew orchids and other
plants to assist taxonomists in England in the 1800's.
This species bears an insectival labellum that is attached to a
stem, which holds it aloft. This has an elastic hinge that can only be
moved backwards where the broadly winged column carries the pollina and
stigma.
The elaborate labellum structure is not sensitive and needs
considerable force to be moved. This force is applied be fast flying male
wasps deceived by the resemblance to the flightless females and the
orchids pheromones, which are similar to that which the female gives off
when they are ready to mate.
The male grasps what he believes to be a
receptive female, overcomes the resistance of the elastic hinge and is
catapulted backwards so that the back of his head is forced against the
column. If he is carrying pollen, it is transferred to the stigma, or,
alternatively, he receives a daub of pollen attached to his head for
transfer to the next orchid he visits. A truly remarkable mechanism that
is highly successful in fertilising the orchid and perpetuating the
species.
There are four named species, (Drakaea elastica, Drakaea
glyptodon, Drakaea livida and Drakaea thynniphila.), five in
manuscript awaiting validation under the 'code', and three hybrids.
The species is presumed to have a one to one pollinating
strategy where one insect type (wasp) pollinates one species and no other.
However the presence of hybrids suggests otherwise.
Ron Heberle. April 2003
|