Orchid of the Week: Angraecum sesquipedale

The orchid I’ve chosen to feature this week is super interesting in terms of its contribution to science, courtesy of one Mr. Charles Darwin.

Charles Darwin is best known for his theory of evolution; many biology classes educate students about his work with finches and tortoises on the Galapagos Islands. Less widely known is Darwin’s work with orchids, though when you consider the vast array of evolutionary variety in the orchid family, it’s not surprising that he took an interest in them. Darwin is most often associated with the Angraecum sesquipedale, AKA Darwin’s orchid, Christmas orchid, and Star of Bethlehem orchid.

The blooms are waxy and each has a long spur containing the plant’s nectar. The spur is the green tubular part next to the stem (you can kinda see it in the pics below). The New York Botanical Garden has some Darwin’s orchids on display:

Angraecum sesquipedale
Darwin’s orchid at the NYBG Orchid Show 2010

Considering the hard-to-reach pollen inside the spur, Darwin wondered how fertilization could possibly take place. He experimented with pollinating these flowers and theorized that a (then-undiscovered) moth must have evolved a proboscis long enough to reach the nectar in the bottom of the spur. The moth would trigger the release of pollen while withdrawing its proboscis, which would allow it to fertilize another flower by inserting its pollen-coated proboscis to get to more nectar. Years after Darwin’s death, this very moth, a ‘hawk moth‘, was discovered in the same region where the Angraecum sesquipedale lives. Darwin FTW!

Angraecum sequipedale flowers
Photo credit: Quimbaya, Flickr

And there’s my attempt at writing about something scientific. Gotta love science! Evolution: it’s real.  🙂

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  1. The sad part is, the moth wasn’t found until after his death, he never got to see it.

    Here is a youtube video about it: http://bit.ly/bjDVOU

    Here you can see how Phil’s patience paid off. Until two years ago, they didn’t know if the moth still existed. This is the first live filming of the moth visiting Angraecum sesquipedale in Madagascar. A beautiful piece of photography: http://bit.ly/c0yJmk


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