Country of Origin: Madagascar - Fort Dauphin to Antalaha
Habitat: hot lowlands on the east coast, 0-100m
Description: This orchid has a nectar tube of 10-12 inches in length with only the distal end filled with nectar. Charles Darwin postulated that there must be an as yet undiscovered moth with a proboscis cabable of extending to 11 inches that visits this flower. This moth (Xanthopan morgani praedicta) was 'discovered' over 41 years later in 1903 even though its existence had been postulated earlier.
From: Darwin, C. R. 1862. On the various contrivances by which British and foreign orchids are fertilised by insects, and on the good effects of intercrossing. London: John Murray.
I fear that the reader will be wearied, but I must say a few words on the Angræcum sesquipedale, of which the large six-rayed flowers, like stars formed of snow-white wax, have excited the admiration of travellers in Madagascar. A whip-like green nectary of astonishing length hangs down beneath the labellum. In several flowers sent me by Mr. Bateman I found the nectaries eleven and a half inches long, with only the lower inch and a half filled with very sweet nectar. What can be the use, it may be asked, of a nectary of such disproportional length? We shall, I think, see that the fertilisation of the plant depends on this length and on nectar being contained only within the lower and attenuated extremity. It is, however, surprising that any insect should be able to reach the nectar: our English sphinxes have probosces as long as their bodies: but in Madagascar there must be moths with probosces capable of extension to a length of between ten and eleven inches!
Culture: Warm or intermediate epiphytic grower. Culture not difficult if several rules are followed:
Once it reaches flowering size, disturb roots as little as possible. Use coarse bark to minimize repotting requirements
Provide plenty of light, especially Aug-Oct, plant will tolerate some foliar burning.
Fertilize and water heavily during summer months. Provide high humidity and good air movement.