The Eucalyptus recurva is considered Australia's rarest eucalypt. Discovered as a botanical curiosity, the largest specimen is estimated to be between 3,000 and 6,000 years old based on its woody lignotuber. The tree has small, beautifully recurved leaves, and is thought to be a remnant from the last ice age.
"When it was first found, it was a real botanical curiosity," said Genevieve Wright, senior threatened species officer with the NSW Saving Our Species program.
Peter Bredell, senior conservation horticulturist at the Australian National Botanic Gardens (ANBG) in Canberra, said his first reaction on seeing the gum was "that's not a eucalypt." He described it as probably the rarest and most threatened eucalypt in Australia.
"We think that it's really the last six of an ancient, remnant species that was around back in the ice age," Mr Bredell said. "If anything happens to those plants, we're really facing an extinction of the species."
The tree cannot reproduce naturally in the wild because the remaining plants are too far apart. There are no wild seeds, and the species has "no future and is facing extinction without intervention," according to Mr Bredell.
Over decades, a collaborative team of ecologists and horticulturalists has worked to clone the tree by grafting wild cuttings onto hybrid Eucalyptus recurva rootstock in the nursery at ANBG. The result is multiple copies of four of the six wild plants, now held safely as an insurance population.
The next challenge is to get the cloned trees to flower. Flowering is fickle and can take up to 20 years. Individual plants flower at different times, making it difficult to achieve the simultaneous flowering needed for pollination, fruiting and production of genetically pure, viable seeds.