This has to be seen to be believed! In September 2001 Francisco J. Díez reported movement of the androgynophore, the stalk in the middle of the flowers, in some Passiflora flowers when it was tapped on the side. Mauro Peixoto in Brazil also confirmed this in P. sanguinolenta. Francisco took the two .mov file movies below of P. 'Sancap', a Leopold Ševcic hybrid of P. sanguinolenta x P. capsularis, which show the movement in real time from two different angles. He suggests that other Passiflora in section Xerogona such as P. capsularis may also show this phenomenon. He comments that 'It seems that light and temperature conditions affect the intensity of the movements very much. It is probably for this reason that a lot of people haven't observed the phenomenon yet.'
P. 'Sancap' 1 © 2002 Francisco J. Díez All Rights Reserved.
P. 'Sancap' 2 © 2002 Francisco J. Díez All Rights Reserved.
Mark Cooper has observed movement in P. citrina. Les King has observed it in P. sanguinolenta x P. citrina hybrids that he has grown from seed, & I have observed it in the same cross, P. ' Betsie Greijmans' by Henk Wouters. In all cases the androgynophore clearly curves quickly in the direction of the blow. Xerogona are primarily thought to be pollinated by small hummingbirds it may be that as they put their tongues into the nectar at the foot of the androgynophore that they hit it with their heads & trigger the bending of it towards them which then dusts them with pollen & picks up pollen from previously visited flowers.
P. incarnata opening This particular flower was filmed over the course of an afternoon from around 1:00 PM until 4:30 PM. Once the petals began opening. they unfurled in about ten minutes. Note that the stamens are initially held well above the anthers but after about two hours they bend down bringing the stigma close to the anthers. On the vine this flower came from, Carpenter bees were busy gathering nectar from the area below the anthers. While collecting nectar from flowers that still had the stigmas in the upright position, the backs of the bees became covered with pollen from the downward facing anthers. When these bees then visited flowers that had opened earlier and the stigmas were facing down, pollen was readily transferred to the stigmas. This seems like a handy mechanism for facilitating cross pollination.
P. incarnata phase 1 The movie shows a bee collecting nectar from a newly opened flower that still had the stigmas in the upright position. The hair on the bee's back became covered with pollen from the downward facing anthers but the bee never made contact with the upward facing stigmas.
P. incarnata phase 2 The movie shows the same bee from the phase 1 flower when visiting another flower that had already turned its stigmas into the downward orientation. With the stigmas bent over the bee's back rubs the stigmas while continuing to forage for nectar. Since the its back was covered with pollen from other flowers, pollen is easily transferred.
* All images & text re P. incarnata © 2000 Dr Roger P. Hangarter. Indiana University, Department of Biology, 915 E 3rd St, Bloomington, IN 47405. All Rights Reserved. See further stunning images of movement in plants at Plants in motion.