An orchid that unfurls its petals at night and loses its flowers by day has been found on an island off the coast of Papua New Guinea.
The plant is the only known night-flowering orchid and was collected by botanists on a field trip to New Britain, an island in the Bismarck archipelago.
The flowers of the species, Bulbophyllum nocturnum , are thought to be pollinated by midges and last for only one night, according to a description of the plant published in the Botanical Journal of the Linnean Society .
Orchid specialist Ed de Vogel, from the Netherlands, discovered the unusual flowering after he gathered some of the plants from trees in a logging area on the island and returned home to cultivate the orchids at the Hortus Botanicus in Leiden. Most orchids are epiphytes, which means 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 several 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.
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.
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.
In 1862, Charles Darwin correctly predicted that the Christmas star orchid, which is endemic to Madagascar, was pollinated by a moth with a 30cm-long proboscis. The moth in question was not discovered until 20 years after his death. The small night-flowering 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 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.
Andre Schuiteman, an orchid specialist at the Royal Botanic Gardens in Kew 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. which are disappearing fast.” — © Guardian Newspapers Limited, 2011
