March 2014 Winning Picture

03 PM Arachnorchis c

Taken at the same site as February’s winning photograph – Ramsay Conservation Park on Yorke Peninsula, the winning photograph was of an Arcahnorchis sp. by Pauline Meyers.

A positive identification was not possible due to a number of factors making firm identification difficult.  Most likely it is a hybrid of the Green-combed group of spider orchids and though not positively identified there are some things that can be observed.  The Green-combed group according to Gary Backhouse consists of three sub-groups, A dilatata (largest sub-group), A concinna and A integra, but David Jones has them as three separate gorups.

Some features of this group are

  • One of two flowers
  • Flowers mainly green or greenish and red
  • Labellum
    • Hinged and mobile
    • Maroon apex
    • Green comb-like teeth on the margins (edges)
  • Tepals (petals and sepals)
    • Green to greenish with red stripes
    • Brown to yellow clubs at the tips

From the photograph it can be seen that all the green-comb features are visible except for the clubs,  The dorsal sepal is obviously thickened but it is not as clear for the other two sepals.  This could be due to the angle of the photograph.

Another observation to note is that it is a freshly opened flower as suggested by the elongated appearance of the labellum.  As the flower ages the labellum curls further under itself.  It is important to remember that an old flower and a young flower of the same species could be mistaken as two different species.

In South Australia, species belonging to the green-comb groups are

  • A dilatata sub-group consisting of
    • A aurulenta, A clavula, A dilatata, A interanea, A macroclavia, A necrophylla,  A parva,
      A phaeoclavia, A septuosa, A stricta, A tensa, A tentaculata, A verrucosa, A villosissima
  • A concinna sub-group consisting of
    • A toxochila, A conferta
  • A integra sub-group consisting of none in South Australia

To iterate from last month – Orchids are an interesting group concerning identification.  Some are extremely easy to identify but others not so.

References:

Backhouse,  G.  (2011).  Spider-orchids  –    the  Genus Caladenia and its Relatives in Australia on CD Rom.
Jones, D. L. (2006). A Complete Guide to Native Orchids of  Australia  including  the  Island  Territories,  (2nd  ed.).  Frenchs Forest, N.S.W., Reed New Holland.
R.J.Bates.  (2011).  South  Australia’s  Native  Orchids (DVD) [Electronic Version]

Thank you to Thelma Bridle for reviewing the article.

 

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