Genes, seasonal conditions or pure chance?

Leo Davis is an orchid hunter.  He is meticulous in his observations and notes details that many of us may miss.  In this article he muses upon the variations that he sees in the field.

You, as I do, must occasionally come upon an orchid or an orchid event that is a little outside normal experience.  When I do, I wonder whether this is a purely chance event or is it caused by recent local environmental factors, or is it due to the genes of the plants.  Or a combination of these?

I’ve been watching a couple of patches of fire orchids (Pyrorchis nigricans) that many of you will be familiar with, one at Knott Hill N.F.R., the other at Monarto C.P., where a few plants flower every year, without the normally required stimulation by fire.  I need to check whether it is the same plants that flower each year.

Pyrorchis nigricans.jpg
Pyrorchis nigricans (Fire or Undertaker Orchid) Photo: Leo Davis

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The tall leek orchid (Prasophyllum elatum) puts up leaves at Scott Creek C.P. every year but does not flower. A fire swept through in early 2014 and most plants flowered in October.  They’ve not flowered since.  But over at Ramsay Way, west of Pt. Vincent, a few plants flower each year without fire.  I assume genes are involved.

Prasophyllum elatum
Prasophyllum elatum (Tall Leek Orchid) Photo: Leo Davis

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In April 2014 I chanced upon a patch of Adelaide Hills parson’s bands (Eriochilus collinus), along Moore’s Road, at Morialta C.P., in which the majority of plants had three flowers per stem. Was this because of favourable conditions or genes? Over the next two seasons I saw only the occasional double header and mainly single flowered plants. I will continue observations and records.   

 Eriochilus collinus

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In July 2015 I found a dense patch, about 3 m2 in area, of hundreds the common mallee shell orchid (Diplodium dolichochilum), in Ferries-McDonald C.P. As usual less than ten plants were in flower, but two of them were double headers.  I’ll be checking this season and expect this not to be a chance event but one due to genes.

Diplodium dolichochilum
Diplodium dolichochilum syn. Pterostylis dolichochila (Slim Tongued Shell or Common Mallee Shell Orchid) Photo: Leo Davis

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

On May 27, 2012, Bob Bates led a NOSSA outing to Scott Creek C.P. and as ever, when he leads, we saw and learned a lot.  He showed us a patch of fringed hare-orchids (Leporella fimbriata) that he assured us should not be growing there on that steep rocky site and that the plants would not flower most years.  Unfortunately he was right, as usual.   I could not find plants in 2013 and 2014 and it took three searches in 2015 to find a very few leaves. On May 10 this year, over an area of less than 10 m2, I found perhaps 50 leaves and just seven plants in flower.  Three of these had three flowers and a tiny unopened bud (check the photo) and the others were doubles.  I’ve never seen a triple flowered plant in hundreds I’ve seen at Knott Hill N.F.R.  Are genes in an isolated population at play here?  Given the paucity of flowering at this site, it may take me years to sort this one out.

Leporella fimbriata
Leporella fimbriata (Fringed Hare  or Ballerina Orchid) Photo: Leo Davis

Leo Davis.

 

Morialta Orchids

100 years ago on 15 July 1915,  the state government declared Morialta a National Pleasure Resort.  The Friends of Black Hill and Morialta have been holding a series of public events to celebrate the Centenary of Morialta.  As part of the celebrations, the Native Orchid Society of South Australia has conducted some orchid walks in the park.

In 2004, an interim Flora Species List was produced by the then Department for Environment and Heritage and 39 orchid species were listed. It is an interim list and considering that the park is 5.33 square kilometres with a range of different habitats, it is possible that there are more species than originally listed.

One native species not included on the list is Caladenia latifolia but its presence is well known to members of the Native Orchid Society.  Unfortunately the South African weed orchid Disa bracteata (Monadenia bracteata) has also been found in the park.

In this video most of the shots have not been taken at Morialta but it does showcase some of the orchids that can be found in the park.