Botanic Gardens Trust, Sydney, Australia

Terrestrial Orchid Conservation

Dr Karen Sommerville - Technical Officer 
 
There are currently 47 terrestrial orchids listed as threatened under the NSW Threatened Species Conservation Act (1995). This year we increased our efforts to develop conservation collections for these species with help from the Slade Orchid Fund. Terrestrial orchids have several features that make them trickier to conserve ex situ than most seed-bearing plants - the seed requires a mycorrhizal association to germinate in the wild; it is difficult to distinguish one species in a genus from another when they are fruiting; species within a genus hybridise readily; and once the fruit is mature the seed disperses very rapidly.

In order to develop good seed collections that will be useful for future restoration programs we have begun using the following protocol:

  • The orchid is identified and tagged while in flower
  • Flowers are hand-pollinated to ensure seed set and prevent collection of hybrid seed
  • Pollinated flowers in remote locations are bagged to limit loss of seed
  • Soil samples are collected with the seed pods to enable isolation of the mycorrhizal fungus

The majority of the seed is processed and banked in the NSW Seedbank at the Australian Botanic Garden, Mount Annan and the Millennium Seed Bank at the Royal Botanic Gardens, Kew. A small sub-sample of the seed is sown over the soil samples and incubated in the dark for several months till seedlings develop. The seedlings are then placed on a selective medium to enable isolation of the fungus and, finally, the fungal isolate is tested to ensure it is the correct strain to initiate germination.

We now have seed collections for thirteen of these threatened species and the correct fungal isolates for seven. Fungal isolates for another four species are in the process of being tested. These collections will provide a useful resource both for future restoration programs and for research into the biology of the threatened species.

Diuris-ochroma
Terrestrial orchids Diuris ochroma. Photo: K Sommerville

Diuris-venosa-pollinated-and-bagged
Terrestrial orchids Diuris venosa, pollinated and bagged. Photo: K Sommerville

symbiotic-germination
Terrestrial orchids Diuris bracteata, symbiotic germination. Photo: K Sommerville

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