Journal Number 104
August 2007

THE COLUMN

Queen's Park Orchids
By Eric Scanlen

Kelly Rennell once asserted that Queens Park, the pride and joy of Invercargill, had five species of native orchid growing there.

The Column had been there and to the nearby Andersons Park on a Gastrodia "holiday" in Jan/Feb 2004 [J91:16] and saw only the G. "long column" that Kelly pointed out. That was an education in itself with robust plants growing and seeding under the darkest Rhododendrons and weak pale ones in both the bark gardens and rising through prostrate Erica bushes. The pale ones in the open seemed to be sunburnt and not producing any seed. Perhaps they need the continuous chilling of the deep shade to set seed?

Kelly has recently sent photos to support his claim for the two most interesting species. His 2005 email said in large part:

"This summer my trips have mainly been confined to Queens Park Invercargill. I now have found five orchid species in the park.

1. Gastrodia minor (photos right) about 30 plants in total, most of which
set seed capsules. First found about 21 Dec 04.

2. Gastrodia 'long column' in excess of 200 plants throughout the park (among Rhododendrons, among pine trees and in various new shrubs planted. Pines have been cut down and the stumps remain. Mostly mid-January. Many seed capsules although not all plants set seed.

3. Chiloglottis cornuta. Several dozen plants in an area of pine trees found early Jan but had finished flowering some with capsules.

4. Microtis unifolia common - regarded as a weed by the gardeners.

5. Pterostylis sp. (photo below) The leaves are compact and the flower does not have long lateral sepals (looks rather like the Pterostylis silvicultrix drawing p82 of the 2001 Field guide), Only saw 5 plants but they were earlier than the Gastrodia. I would estimate peak flowering was Nov.

I also saw both G. cunninghamii and G. "long column" at Anderson Park.
The G. cunninghamii was earlier than the G. "long column". Where I put
the netting enclosure around three plants last year, two flower spikes arose
this year and where we found the one out by the gate, alongside the Erica,
there were three plants this year. I have noticed that the plants growing out
in the open tend to be lighter coloured than the ones under shade as one might expect."

Kelly's P. silvicultrix is a convincing image of the Chatham Islands' species although slightly over-mature with shrivelled tepal tips. The short lateral sepals, dorsal sepal tip bunched with lateral petal tips, that characteristic labellum and the broad floral bract all look too good to be true. Could it be? The Chathams species had to have come from somewhere.

It's nice to see good flowers on Gastrodia minor too.
The Journals are strangely lacking in this fairly common and smallest of the Gastrodia's. Notice the tiny column in the sectioned flower. It is obviously equipped for self pollination even though the flowers all open and those ridges of convincing looking pseudopollen on the labellum, lead back towards the column. Still trying for insect pollination seems likely.

Self pollination is only ever a fall back survival mechanism for plants because they lack the adaptive advantages that cross pollinated plants obtain. For G minor, either the pollinator has disappeared or mutation, such as the abbreviated column, has at one fell stroke made insect pollination unlikely and self pollination possible. If the mutation notion were responsible, one can speculate that the non-mutated original with a long column has disappeared from loss of a pollinator?

Interesting that the gardeners regard the self introduced
Australian Microtis unifolia as a weed. You and I could be
arrested for pulling up orchids in a park but the gardeners can
pull barrow loads of "weeds" without a thought. Kelly might be able to sift through a wheelbarrow of weeds for three specimens of this Pterostylis to send to Dr Molloy for positive ID!