Journal Number 104
August 2007

VARIOUS CONTRIVANCES

Waireia stenopetala
The New Zealand terrestrial orchid flora is unique because most self pollinate:
the various contrivances by which the New Zealand orchids are fertilised by themselves are recounted here.

This alpine plant flowers in a harsh, cold, windswept, insect-poor environment, above the tree line.

It is tough, leathery, all green, the combined floral bract and dorsal sepal forming a long cover to protect the reproductive parts of the flower from the elements. The rest of the floral segments almost fill the opening as they emerge.

The flower parts are nicely adapted for self pollination.

The proximal part of the labellum is quite tightly pressed against the column, leaving little room for falling pollen to escape the stigma.

The stigma is immediately below the anther cap, and I could not find a rostellum to separate the two. The pollinia readily dislodge from the anther cap and easily slip down onto the stigmatic surface.

To effect cross pollination, an insect would have to find its way into the flower through the small opening between dorsal sepal and labellum, then insert itself between the labellum and the column, then somehow remove pollinia without allowing any to contact the stigma.

Impossible!