Mystery Tree
April 2010

Mt Stuart has long been a place of interest for viewing native plants. It is close to the city, the peak is accessible by road, and we conduct outings regularly, particularly in February to view the ground orchid, Habenaria triplonema.

Although the entire range is army land, Townsville City Council maintain a Scenic Reserve; which, at 584 metres presents an entirely different landscape from that experienced at sea level. For an ever growinglist of plants that we regularly see, visit our Mt Stuart page.

One species that we have not seen before was recently discovered at the base of a deep gully directly below the peak.  At first sight it has all the appearance of a Gossia, with a smooth mottled bark and dark green, glossy leaves, aromatic and with oil dots.

The Mystery Tree occurs directly on the creek, in the base of the gully; no specimen is growing more than about 2 metres above the bottom of the gully. There are about 120 'mature' specimens with juveniles scattered throughout, over about 350 metres. the majority would be in the range of 4 to 8 metres in height, but at the lower end where the gully opens out, there are several larger specimens, the largest being about 15 metres in height and having a circumference at breast height of 145 cm.

In the upper section, quite a number are multi stemmed, and this would appear to come from coppicing at the base (which is evident in quite a number of specimens throughout - perhaps from a lignotuber or from suckering - which is probably due to the exposed roots sustaining damage from debris in heavy rain periods. There does not appear to be a reason for the coppicing as all appear very healthy from a couple of good wet seasons.

It was not until we found some 'fruit' that the Mystery Tree took on truly mysterious proportions.

The 'fruit'consists of a papery capsule (perhaps 5-8mm)with four distinct 'wings', enclosing a much smaller ovary attached to the base of the capsule.

This arrangement is continuing to bemuse the experts.

DNA testing confirms that it is indeed in the Family Myrtaceae, closely allied to the tribe Backhousieae, but it will take a considerable amount of continuing research to fully understand this Mystery Tree!

Update 2012

Further work depended on collection of flowers and developing fruit so the next flowering was eagerly awaited. Apart from a tiny branch which bore a few flowers late in 2010 – none of the trees flowered in the 2010/2011 wet season! Later analysis of rainfall patterns indicate that flowering occurred in early 2010 and 2012 after a long dry season of 7 months, broken by good rainfall in December.

Having failed to flower and fruit in the 2010/11 season it was impossible to make a clear resolution of the tree's identity. 
This led to some frustration as we were making regular visits every 3 to 4 weeks, and it was not until 13th January 2012 that we found a large number of the trees covered with buds, and the first of the flowers on show.

This led to a flurry of visits over the next three week, as the flowering and development of fruit happened very quickly and specimens were collected at all stages of development.

Whilst these specimens were collected, further work at JCU included preparation of slides for microscopic analysis of the cell structure of leaves, stems etc and similar examination of the flowers and fruits as available. The preliminary description of the new discovery was also prepared ready for publication. The genus of the proposed name has been established by analysis as Backhousia, but John has the honour of nominating the species name to be given.

The species name of tetraptera describes the very distinct four winged fruit.   

Following this story from the start has been a wonderful experience and we have learned so much about the intricacies of plant taxonomy and the need for careful and detailed analysis when dealing with plant identification.

So Backhousia tetraptera is now the scientific name, but it will always remembered as our Mystery Tree!

Here you will find the relevant section of the paper, written by Dr Betsy Jackes, and published in:

Australian Systematic Botany 2012 25, 404-417

Published online ,14th December 2012.