R. Luyt et Sd. Johnson, Hawkmoth pollination of the African epiphytic orchid Mystacidium venosum, with special reference to flower and pollen longevity, PLANT SYS E, 228(1-2), 2001, pp. 49-62
The pollination biology of Mystacidium venosum Harv. ex Rolfe, an epiphytic
orchid endemic to southern Africa, was investigated. The white flowers of
this orchid have long spurs (c 4.5 cm) and contain dilute sucrose-dominated
nectar which is secreted during the afternoon and early evening. Scent, do
minated by Jasmine lactone and (E, E)-Farnesol, is emitted in the evening.
A breeding system experiment established that self pollination results in i
nferior quality fruits. Field observations at three sites in Kwa-Zulu Natal
, South Africa, in 1998 and 1999 showed that hawkmoths were frequent visito
rs to the orchid shortly after dusk, and carry pollinaria along the length
of their tongues. No evidence for directional selection on spur length was
found at any of the three sites. Results showed that flower longevity is st
rongly reduced by pollination, while pollinaria removal had only a small ef
fect. Pollinia removed from flowers remained viable for up to 20 days under
outdoor conditions.