AOBPreview originally published online on April 27, 2004
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Annals of Botany 93: 773-781, 2004
© 2004 Annals of Botany Company
Pollination Ecology of Four Epiphytic Orchids of New Zealand
1 Allan Wilson Centre for Molecular Ecology and Evolution, Massey University, Private Bag 11 222, Palmerston North, New Zealand and 2 Ecology Group, INR, Massey University, Private Bag 11 222, Palmerston North, New Zealand
* For correspondence. E-mail c_lehnebach{at}hotmail.com
Received: 22 September 2003; Returned for revision 8 January 2004; Accepted: 20 February 2004; Published electronically: 27 April 2004
• Background and Aims In New Zealand epiphytic orchids are represented by four genera and eight species. The genera Earina (three species) and Winika (one species) are the most conspicuous and widespread. These are likely to be some of the southernmost distributed genera of epiphytic orchids in the world.
• Methods To identify the pollination strategies that have evolved in these orchids, hand-pollination treatments were done and floral visitors were observed in several wild populations at two areas of southern North Island (approx. 40°S). Pollen : ovule ratio and osmophores were also studied and the total carbohydrate content of the nectar produced by each species was measured.
• Key results Earina autumnalis and Earina mucronata are self-compatible, whereas Earina aestivalis and Winika cunninghamii appear to be partially self-incompatible. All four orchids are incapable of autonomous selfing and therefore completely dependent on pollinators to set fruits. Floral visitors observed in the genus Earina belong to Diptera, Coleoptera and Hymenoptera and to Diptera and Hymenoptera in W. cunninghamii.
• Conclusions Contrary to many epiphytic orchids in the tropics, the orchid–pollinator relationship in these orchids is unspecialized and flowers are visited by a wide range of insects. Putative pollinators are flies of the families Bibionidae, Calliphoridae, Syrphidae and Tachinidae. All four orchids display anthecological adaptations to a myophilous pollination system such as simple flowers, well-exposed reproductive structures, easily accessed nectar and high pollen : ovule ratios.
Key words: Bibionidae, Calliphoridae, Diptera, Earina aestivalis, Earina autumnalis, Earina mucronata, epiphytic orchids, New Zealand, Orchidaceae, generalist pollination, Syrphidae, Tachinidae, Winika cunninghamii.