An Eriochilus study in the Southern Flinders Ranges: 2010

R. Bates

Until  2009 when NOSSA did an orchid study of Wirrabara Forest Reserve the parsons bands or Eriochilus were thought to be rare in the Flinders Ranges, but that year Eriochilus were found all the way north to Mount Remarkable and were often seen as locally common.

In 2010 I did two visits, one in April and one in May to see how well they flowered after a wet spring the previous year.

Results: all colonies at Wirrabara flowered spectacularly in April 2010 but at Mt Remarkable flowering was poor.  No leaves were visible at the time.  The flowers were white with some strong colour and stems were quite bristly, see image. At Wirrabara plants were sturdy with up to four flowers per scape yet at Mt Remarkable plants were spindly and flowers mostly single.

It was thought that the reason for this difference lay in the wet spring of 2009 at Wirrabara with much less rain at Mt Remarkable.

The second visit in May showed a different picture. Very little rain had fallen at Wirrabara in autumn and the stems of all plants had hardly elongated.  Yet seed capsules were plentiful.  In contrast, Melrose near Mt Remarkable had received good autumn rain and stems there had doubled in length.

So it seems that the number of flowers and strength of plants depends on rain the previous season whilst height of stems depend on rain during the current flowering season.

Curiously, in both areas a second flush of flowering occurred in May with the second flush at Wirrabara producing tiny flowers on short spindly stems (see image) while those at Mt Remarkable had larger flowers on tall stems.

Flowers seen in both areas were similar in appearance and both had leaves which were large, apiculate, dark green, ribbed and hairy above, purple below.  Both the April flowered and May flowered plants belonged to the same taxon and clearly flower size and number, and scape length, are not useful in separating species as they are so variable.

On the other hand leaf shape, texture, ribbing and colour below are important in identifying the species as these are constant features.

Conclusions: only one species of Eriochilus occurs in the Flinders Ranges and this is the same as the common woodland species in the Mt Lofty Ranges.  This species has never been named officially but is generally known as Eriochilus sp Hills woodland and is best identified by it’s leaf … see image.

This is the most common of three or four Eriochilus species in SA.

Leaf of April flowering Eriochilus at Wirrabara dwarfing later May flowered
plants behind it.

Eriochilus species Hills near Mt Remarkable in May 2010

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