Large Bird Orchid

Description:

These were low growing from two oval shaped leaves up to about 70mm above the ground and about 40mm wide. Roughly half a dozen calli occur in the rear part of the labellum plus a single taller stalked callus standing in the back. The calli decrease in size to the front.

Habitat:

In a dry sclerophyll forest dominated by silver leafed stringybark eucalyptus. Baluk William Flora Reserve.

Notes:

These plants have active seasons of growth and dormancy and only grow in areas with a seasonal climate and are responsive to the effects of fire.
The orchids dupe male Thynnus sp. (flower wasps) by producing the 'scent' of a female wasp. The flower has a large labellum including a group of dark, shiny calli (stemmed knobs and buttons) with a particular 'insectiform' arrangement. The broader callus at the centre is what the male wasp grasps at causing the labellum to collapse upwards. The wasp’s thorax is then coated with pollen as it fights it's way out.
It is possible to tell one orchid species from another by their particular species of pollinator.
http://bie.ala.org.au/species/urn:lsid:b...
http://plantnet.rbgsyd.nsw.gov.au/cgi-bi...
http://fe.yarraranges.vic.gov.au/Residen...
Also found in the same area in mid-summer the Small tongue orchid http://www.projectnoah.org/spottings/115...