Saturday, November 26, 2011

Botanists discover ‘remarkable’ night-flowering orchid in Papua New Guinea

A NIGHT-flowering orchid, the first of its kind known to science, has been described by a team of European botanists in Papua New Guinea.
The Bulbophyllum nocturnum is the first orchid species, out of about 25,000, to only flower at night

Experts say the “remarkable” species is the only orchid known to consistently flower at night, but why it has adopted this behaviour remains a mystery, BBC News reports this week.
The plant was discovered by a Dutch researcher during an expedition to West New Britain province.
The findings have been published in the Botanical Journal of the Linnean Society.
“It was so unexpected because there are so many species of orchids and not one was known (to flower) at night only,” said co-author Andre Schuiteman, senior researcher and an orchid expert at the Royal Botanic Gardens, Kew, England.
“It was quite remarkable to find one, after so many years of orchid research, that is night-flowering,” he told BBC News.
The specimen was discovered by co-author orchid specialist Ed de Vogel during a field trip in a region of lowland rainforest in the province although the exact local was not disclosed.
Its unique flowering behaviour only came to light after the specimen was taken back to the Netherlands, said BBC News.
Dr de Vogel had gathered some of the plants from trees and returned home to cultivate the orchids at the Hortus Botanicus in Leiden. Most orchids are epiphytes, which mean they take root on trees.
The botanist was particularly eager to see the orchid’s flowers because it was a member of the Epicrianthes group of orchids. This group contains many rare species that have bizarre flowers with strange appendages, which often resemble leggy insects, small hairy spiders or intricate sea-creatures
The appendages are usually attached by thin filaments, which allow them to move erratically in the slightest breeze. Many have only been discovered recently as they occur in some of the remotest jungle habitats on earth.
As de Vogel cultivated the orchids, he noticed flower buds appear but instead of opening to reveal their petals, they simply shrivelled up and died.
He finally realised what was happening when he took one of the plants home and saw its flowers open around 10pm one night and close again soon after sunrise. The flowers opened for one night only, explaining why the buds appeared to be preparing to open one day, yet be withered the next day.
Flowers that open only at night are seen in a small number of plant species, such as the queen of the night cactus, the midnight horror tree and night blooming jasmine. Bulbophyllum nocturnum is the only orchid among 25,000 species that is known to do so. Many orchids are pollinated by moths and other nocturnal insects, but have flowers that remain open during the day.
The specimen has been identified as belonging to the Bulbophyllum genus, which – with about 2,000 species – is the largest group in the orchid family.
While there are a number of orchids that do attract night-time pollinators, B. nocturnum is the first known species that exclusively flowers at night.
The small orchid has yellow-green sepals that unfurl to reveal tiny petals adorned with dangling, greyish, thick and thin appendages. The flower, which is 2cm wide, has no noticeable smell, though some nocturnal species can time the release of their scents to attract night time pollinating insects.
Writing in the journal, the authors point out the striking resemblance between the flowers' appendages and the fruiting bodies of certain slime moulds found in the same part of the world. The similarity led the botanists to speculate that the orchids might be pollinated by midges that normally feed on slime moulds or small fungi.
Schuiteman said it still remained a mystery why the plant had developed such behaviour.
“We think related species are pollinated by tiny flies that think they are visiting fungi,” he explained.
“The flowers mimic fungi, that’s what the details of the flowers look like they do.
“The flies are looking for somewhere to lay eggs, and it is most probably (a species) that forages at night.”
He added: “The orchid probably has a smell, not detectable by humans, to attract insects from a distance – and when they are nearby, the shape and physical aspects of the flower probably play a role too.
Schuiteman said the exact reason why B. nocturnum only flowered at night would remain a mystery until further field studies had been completed.
However, time may be against them as the location in West New Britain where the original specimen was found lay within a logging area.
“It was previously inaccessible but now the area has been opened by logging,” Schuiteman said, adding that was an area that needed to be explored because there were probably many more species waiting to be described.
He said the logging activity was a double-edged sword because the Papua New Guinea government had granted logging licences in the area meant that it created roads that had allowed the plant hunters to carry out their exploration, yet it was an activity that could threaten the long-term survival of the species.
“My colleague who discovered it got permission from the logging company to go into the area, they even gave him a car to use.
“They realised that it would have been a shame to log the trees and destroy the orchids because they would be left lying on the ground exposed to full sunlight.”
He called for areas to be left untouched: “It is the government that gives permits to log a particular area, so we should be asking them to protect areas and not issue permits for everything.”Schuiteman said: “This is another reminder that surprising discoveries can still be made. But it is a race against time to find species like this that only occur in primeval tropical forests. As we all know, such forests are disappearing fast.”
Botanists at Kew Gardens hope to get a cutting from the orchid in Leiden to cultivate within the next few years. A specimen preserved in alcohol is already held at the site’s herbarium.

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