Charles Darwin, the renowned naturalist who proposed the theory of natural selection had a thing for orchids. He had studied thousands of plants and animals prior to the publication in 1859 of the seminal work “On the Origin of the Species”, but the orchid held special interest for him.
Darwin had long been fascinated by insect pollination and had studied the wild orchids found along the Torquay coastline while on family holidays. In particular, he examined how the different petal colours and formations attracted bees and moths to pollinate the plants. Challenging the idea the huge variety in flowers served no real purpose other than beauty, Darwin contended that there must be a reason why each variety of flower – the array of different shapes and colours – looked as they did.
Knowing of his interest in orchids, the horticulturist James Bateman sent Darwin several examples of Angraecum sesquipedale, which had been discovered by French botanist Louis-Marie Aubert du Petit-Thouars in 1798, but only described in 1822.
The orchid, also known as the Star of Bethlehem orchid and King of the Angraecums, was an impressive flower only found on the island of Madagascar.
What made the flower so remarkable was the length of its spur – 14 inches from the lip of the orchid to the end. This meant that the nectar was a foot away from any insect hoping to feed from and thereby pollinate the plant.
“I have just received such a box full from Mr Bateman with the astounding Angræcum sesquipedalia with a nectary a foot long— Good Heavens what insect can suck it?” commented Darwin.
He concluded in his book ‘Fertilisation of Orchids’ that somewhere there must be an insect with a proboscis long enough to reach the nectar, although no insect had ever been seen which would be capable of the feat.
Darwin died in 1882 without an answer to the riddle. It wasn’t until 1903, over twenty years after his death, that a giant hawk moth Xanthopan morgani (or Morgan’s Sphinx) was discovered in Madagascar.
The giant moth was observed to unroll a proboscis over a foot in length and feed from the orchid, proving that Darwin had been correct in his supposition all along.
