Floral biology and flower visitors on subantarctic Campbell Island

Abstract

Island plants often show reduced floral pigmentation and display size compared with mainland relatives, which is commonly thought to relate to a lack of specialized pollinators. Some species on New Zealand's subantarctic islands have spectacular, highly pigmented inflorescences, yet the depauperate insect fauna provides little apparent opportunity for biotic pollination. We document breeding systems and floral visitors for six Campbell Island species. All species tested had lipid-rich rather than starchy pollen and some produced nectar. Pleurophyllum hookeri appeared to be self-incompatible, but P. criniferum, Veronica benthamii and Damnamenia vernicosa were all capable of selfing. Daytime floral visitors were predominantly small Diptera and the flightless Muscid, Coenosis filipennis. The nocturnal wētā, Notoplectron campbellensis (Orthoptera), visited V. benthamii flowers and carried pollen between male and female plants of Anisotome latifolia and Bulbinella rossii. Biotic pollination might be more important in the subantarctic than previously thought and wētā are possibly key flower visitors.