CHARLES DARWIN did not live to see the moth with the extraordinarily long "tongue", but he knew it existed.
It was in the 1860s that scientists first stumbled across the Star of Bethlehem, a bizarre Madagascan orchid which stores its nectar at the bottom of a tube up to 30 centimetres long.
"When Darwin saw the flower and saw the great long tube," said Tim Entwisle, executive director of Sydney's Botanic Gardens Trust, "he realised there must be an animal that can get the nectar out if the orchids were to be pollinated. Darwin was laughed at. No such animal had ever been heard of."
But in 1903, 21 years after his death, the mysterious pollinator was found. A hawk moth with a proboscis long enough to reach the bottom of the orchid's nectar tube or "spur" was named Xanthopan morganii praedicta - honouring Darwin's prediction.
Two of the orchids are now blooming in the tropical centre at Sydney's Royal Botanic Gardens.
"They are quite rare," said Dr Entwisle, adding that their real significance was that their very existence supported evolution.
"It is one of those fascinating stories of evolution, about an animal and a plant that fit together. It's the perfect example of mutual dependence."
But which came first, the orchid or the moth?
"That's an interesting question," said Dr Entwisle. "They probably both evolved together, maybe starting with an orchid with a small tube and a moth with a small proboscis."
Over time both grew longer and longer.
However, the two orchids in the botanic gardens will wait in vain for pollination.
"There are a few flies in the tropical centre, but certainly no Madagascan moths," he said.
While it would be possible to artificially pollinate them in the laboratory, Dr Entwisle expected the orchids would be left to grow and flower, without reproducing. "We can split them if we need to."
The orchids, expected to be in flower for at least another couple of weeks, are on public display from 10am until 4pm. Entry to the tropical centre costs $8.80 for families and $4.40 for adults |
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