Which orchid inspired Darwin’s prediction of a moth with an exceptionally long proboscis?

Angraecum sesquipedale inspired Darwin’s prediction of a moth with an exceptionally long proboscis.

This white, star-shaped orchid from Madagascar has a nectar spur that can be more than 25 centimetres long. After examining the flower, Charles Darwin and Alfred Russel Wallace reasoned that an insect with a matching feeding organ must pollinate it.

Darwin discussed the orchid in his 1862 book Fertilisation of Orchids. Decades later, the hawkmoth Xanthopan morganii praedicta was identified as the pollinator associated with the flower. Its extended proboscis can reach the nectar at the bottom of the spur while the moth contacts the orchid’s pollen structures.

The orchid’s name means “one and a half feet,” referring to the long spur. The famous prediction was about a moth adapted to the flower, not about the orchid evolving an animal or producing nectar without pollination.