Translocation of the Critically Endangered Bancroft's Symonanthus: Symonanthus bancroftii

Symonthanthus bancroftiA joint project with the Department of Parks and Wildlife Narrogin District (now Yilgarn district) and Bruce Rock LCDC, with Dr Eric Bunn, Senior Research Scientist, BGPA, as project leader.

This may be the ‘rarest plant on earth’, as only one ‘male’ plant and some 500 m away one ‘female’ plant were known to exist in the wild since 1997 – too far apart to allow natural pollination.

Three translocation sites have been established since, to investigate, if it is possible to grow this species and produce viable seed. All three tissue cultured clones (father, mother, and daughter later raised in Kings Park) were planted on each site, have flowered well and the females have produced viable seed.

This is a difficult species to cultivate and to grow on. Ripping the sites, the use of reticulation and improved horticultural techniques are gradually improving the survival rates. Small quantities of seeds have been collected for several years and seed treatments as well as germination requirements are being investigated on old and new seed, and long term seed burial trials are in progress to investigate seedbank longevity. Seedlings generated from site collected seed have been planted before, producing very poor survival rates. However those planted in 2008 on a deeply ripped site are progressing well and several were flowering within the first season of planting.

Fortunately seedlings from harvested seeds are about a 50% mixture of male and females, which will ensure good pollination and seed production in future. Seed is being collected for long term storage at BGPA and DEC and clonal material is in cryo-storage at Kings Park to ensure the long term survival of this genetic material.

On-site aerosol smoking trials were initiated in April 2011 to try and stimulate the soil seedbank to germinate as no seedling recruits have been found on any of the sites in previous years. Seedling recruitment is completely dependent on sufficient winter rainfall events.

We are hoping new wild plants will be found in future to add to the genetic diversity of this species. Funding has been predominantly from Natural Heritage Trust.

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