Friday Fellow: Darwin’s Orchid

by Piter Kehoma Boll

Orchids comprise one of the most numerous families of plants, so it is more than time to have an orchid Friday Fellow. And what could be a better choice than the Darwin’s orchid, Angraecum sesquipedale?

Native from Madagascar, the Darwin’s orchid has nice star-like white flowers with a waxy appearance that are produced in the wild from June to September. It is an epiphytic orchid, growing on trees, and its roots may reach several meters in length around the tree trunks.

The white waxy flowers of the Darwin's orchid. Notice the long spurs hanging from the flowers.

The white waxy flowers of the Darwin’s orchid. Notice the long spurs hanging from the flowers. Photo by Wilfred Duckitt*.

The most distinct feature of this species is the presence of a very long spur, a tube up to 43 cm long that contains the nectar. The epithet “sesquipedale” is given after that feature, meaning “one and a half foot long” in Latin, referring to the length from the end of the spur to the tip of the dorsal sepal. After examining several flowers, the naturalist Charles Darwin predicted the existence of a pollinator with a proboscis that was long enough to reach the nectar at the end of the spur. Later, Alfred Wallace noticed that the Morgan’s sphix moth (Xanthopan morganii), found in East Africa, had a proboscis almost long enough to reach the nectar and suggested that naturalists should look for similar species in Madagascar. In fact, some time later, specimens of the Morgan’s sphinx moth with a very long proboscis, long enough to reach the end of the spur, were found in Madagascar, confirming Darwin’s prediction. Unfortunately it happened only after Darwin’s death, so that he never became aware of the discovery…

Currently there are many cultivars and hybrids of the Darwin’s orchid all around the world.

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References:

Nilsson, L. A. 1988. The evolution of flowers with deep corolla tubes. Nature, 333: 147-149. DOI: 10.1038/334147a0

Wikipedia. Angraecum sesquipedale. Availabe at: < https://en.wikipedia.org/wiki/Angraecum_sesquipedale >. Access on June 18, 2016.

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*Creative Commons License
This work is licensed under a Creative Commons Attribution 2.0 Generic License.

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1 Comment

Filed under Botany, Evolution, Friday Fellow

One response to “Friday Fellow: Darwin’s Orchid

  1. I saw a beautiful one at the Santa Barbara Orchid Estates in CA.

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