The epiphytic flora of New Zealand has interesting similarities with the epiphytes of tropical rainforests. For example, we have diverse epiphytic species that belong to many different plant groups: ferns, orchids, shrubs etc. However, these groups of plants also have stark differences and today's example is the cacti!
Forget what comes to mind when you imagine a cactus because the cacti of tropical Americas do not grow in sand nor do they have large spikes. Species such as those belonging to Rhipsalis grow as epiphytes and have long leaves without any spikes. They also have tiny flowers and fruit that emerge from the leaves.
Forget what comes to mind when you imagine a cactus because the cacti of tropical Americas do not grow in sand nor do they have large spikes. Species such as those belonging to Rhipsalis grow as epiphytes and have long leaves without any spikes. They also have tiny flowers and fruit that emerge from the leaves.
Epiphytic cactus Rhipsalis baccifera. Photo: Scott Zona
Rhipsalis flower. Photo: Blossfeldiana
Rhipsalis fruit. Photo: orange.tag.pixx
Species of Rhipsalis are thought to have specialist relationships with one group of tropical birds. A recent study by Guaraldo and colleagues compared the requirements for Rhipsalis seed germination to that of mistletoes; a plant group that is considered to rely on specialist dispersers. Both of these plant groups have sticky seeds that are most successful if they are stuck in the fork of a large branch with suitable bark. Species of Rhipsalis are even known as "mistletoe cactus" because the fruit are so similar. Interestingly, the seeds of Rhipsalis and mistletoe species are both primarily distributed by Euphonia birds. These birds do a good job of establishing sticky seeds because they smear the seeds onto a host branch rather than dropping them, providing a much better chance for establishment.
A member of the Euphonia genus that distributes Rhipsalis seed. Photo: Andres Hernandez S.
New Zealand's epiphytic flora does not have any cacti species, nor any known specialist bird relationships. We do know that some mistletoe species rely on tui and bellbirds for pollination and that the woody vine kiekie might have had a relationship with bats in the past (before they were lost from many areas) but these plants aren't epiphytes - maybe epiphytes like the Pittosporum shrubs species have (or had) important relationships with fauna, it is after all still unclear how their seeds are dispersed. Is anyone out there looking for a research topic?!
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