Preliminary studies on ornithophilous floral visitors in the Australian endemic <i>Passiflora herbertiana</i> Ker Gawl. (Passifloraceae)

The pollination biology of the Australian endemic species Passiflora herbertiana (Passiflora subgenus Decaloba, supersection Disemma, section Disemma) was investigated in a single population growing in the Witches Falls section of Mount Tamborine National Park, Queensland. Three native honeyeaters were observed at the flowers, including Lewin’s Honeyeater (Meliphaga lewinii), the Noisy Miner (Manorina melanocephala), and the Eastern Spinebill (Acanthorhynchus tenuirostris). Visitation began at 07:30 and ended by 15:30 each day. The most frequent visitor was Lewin’s Honeyeater. Flowers typically began anthesis in the afternoon, with a small number of flowers opening in the early morning. Flowers remained open between four and five days, even after successful pollination. Both the age of the flower and the amount of sun exposure were determined to affect perianth colour change from pale yellow to salmon-pink. Andromonoecy was observed infrequently in the population; most plants exhibited bisexual flowers, but a small number of individuals exhibited both hermaphroditic and male flowers with short styles held permanently erect. Controlled hand pollinations indicated that P. herbertiana is self-compatible but is not autogamous. Pollen tubes required at least 48 hours to reach the most apical ovules within the ovary. These data provide new insights into the evolution of ornithophily in the Old World Passiflora. Link to Appendix 1: Video showing Lewin’s Honeyeaters visiting various P. herbertiana flower