Hybridization between Amyema pendulum and Amyema quandang (Loranthaceae)

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Abstract
A. pendulum (Sieb. ex Spreng.) Tiegh. and A. quandang (Lindl.) Tiegh. are sympatric and coblooming at a site in the Healesville District of Victoria [Australia]. Within the combined, sympatric populations there were observed 15 morphologically intermediate plants, that were collected. These intermediate specimens showed a very low percentage of viable pollen and a total absence of seed. By fluorescence microscopy, it was shown that A. pendulum pollen adhered, germinated and penetrated the stylar tissue of A. quandang gynoecia in over 70% of in vitro matings. Natural interspecific pollination is possible as the 2 spp. had overlapping vector spectra and floral phenologies. At least 4 spp. of native perching birds in the family Meliphagidae were shown to transport the pollen of both species and to forage for nectar on A. pendulum plants before visiting A. quandang and where thus potential interspecific pollinators. The intermediate specimens were putative hybrids, i.e., A. pendulum (.male.) .times. A. quandang (.female.). However, because of the high degree of sterility and further complications in the life-cycle of the F1 offspring, it is doubtful whether introgression is an important component of the biosystematics of either parent species.