Explosive flowering, nectar production, breeding systems, and pollinators of New Zealand mistletoes (Loranthaceae)
The six New Zealand loranthaceous mis- tletoes fall into two groups based on pollination bi- ology. Four (Alepis flavida, Peraxilla colensoi, P. tetrapetala, and Trilepidea adamsii) are bird polli- nated with hermaphrodite flowers while the other two (Ileostylus micranthus and Tupeia antarctica) are dioecious or sub-dioecious and insect pollinated. We provide data on the pollination biology of the five extant species (Trilepidea is extinct). The two Peraxilla species and Trilepidea have recently been shown to have explosive flowers. Here we show that Alepis has weakly facultatively explo- sive flowers. The world distribution of explosive mistletoe flowers suggests that the syndrome has arisen a number of times independently within the family, and is found in about half the putatively ancestral genera. The principal avian visitors to the bird-pollinated species were tui and bellbirds; introduced species are numerically unimportant as pollinators. The nectar production schedules of Alepis and Peraxilla encour- age single-visit pollination as little nectar is produced after the flowers open. However, when bird densi- ties are high, buds of Peraxilla may be forced open prematurely, encouraging multiple visits.