Megaherbs - Anisotome latifolia

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The Story: A field of megaherbs like jewels on a misty, tussock-clad hillside is an iconic subantartic image. These very special plants are only found on islands of the Subantarctic including Auckland, Campbell, Antipodes, Snares and Macquarie islands in the New Zealand.

Botanical region with one species reaching Stewart Island. As the name suggests they have unusually large leaves and floral structures, and their flowers are frequently densely pigmented compared with mainland relatives. Megaherbs are found in a range of plant families including the daisy family, represented by three species of Pleurophyllum, the carrot family represented by three species of Anisotome, the ivy family represented by Stilbocarpa polaris and the more northerly S. kirkii, and the Asphodel family (Bulbinella rossii). This large leafed growth form has apparently evolved in situ on these islands with recent evidence suggesting that it may confer a thermal benefit in cold cloudy conditions. Megaherbs are also a key part of terrestrial subantarctic food webs, providing habitat and food for large numbers of insect larvae who in turn support populations of insectivorous birds. There is some evidence that insects are attracted to warmer flowers but more research needs to be done to be certain. On pristine subantarctic islands insect larvae are the only consumers of megaherbs but on islands where pigs, goats, sheep and cattle have been introduced, megaherbs have disappeared from all accessible areas. The impact of megaherb lost in most areas of the main Auckland Island is unknown as their importance to island ecosystems is still being discovered, for example recently researchers found the endemic Campbell Island weta visiting megaherb flowers in the middle of the night to feed on nectar. This has not been observed yet for the endemic Auckland Island weta and more research is needed. Thus these plants are not only beautiful and iconic but also an essential component of sub-antarctic systems.

Useful Links:

www.botany.otago.ac.nz


The Scientist: Dr Janice Lord - Senior Lecturer, Otago University.

Janice Lord is a plant ecologist with interests in plant reproduction, plant-animal interactions and traditional uses of plant by Māori. My main research area is the evolution of plant reproductive strategies, particularly how plant pollination and fruit dispersal systems has been influenced by the unique set of animals in New Zealand. Current areas of research activity include pollination syndromes and breeding systems in alpine and subantarctic plants and the role of flower colour in pollinator attraction as well as the impact of climate change on alpine and subantarctic plants and their pollinators.

Janice at work.