Brooklyn Orchids

Orchid of the Week: Pterostylis nutans

This week’s orchid is the Pterostylis nutans, an orchid native to Australia and New Zealand. This orchid has a couple aliases: the Nodding Greenhood and the Parrot’s Beak Orchid. What its scientific name makes me think of is a pterodactyl, but the plant looks more Venus Flytrap than Flying Reptile. This orchid actually traps insects inside its blooms—how very Little Shop of Horrors!

Pterostylis nutans
Image credit: piko.com.au

Pollination is unique with this orchid. The bloom has a hinged lip that swings backward when an insect such as a gnat or mosquito lands on it. The insect is then forced to escape by crawling past the sticky flower pollen which adheres to the insect’s body, ensuring pollination of the next bloom it lands on. Neato!

Pterostylis nutans bloom
Image credit: pacificbulbsociety.org

The Pterostylis nutans pollination story reminds me a bit of the Angraecum sesquipedale (Darwin’s orchid), which was Orchid of the Week about a month ago. It’s just incredible the way orchids have evolved to reproduce the best way possible for their environment. Evolution never ceases to amaze me!

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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