Is Rafflesia an endothermic flower?

Authors

  • Sandra Patiño,

    Corresponding author
    1. Institute of Ecology and Resource Management, The University of Edinburgh, Darwin Building, Mayfield Road, Edinburgh EH9 3JU, UK;
    2. Helsinki Finland;
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  • Tuula Aalto,

    1. Department of Physics, University of Helsinki, PO Box 9 (Siltavuorenpenger 20D), University of Helsinki, FIN−0001
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  • Alice A. Edwards,

    1. Chemistry Department, Universiti Brunei Darussalam, Jln. Tungku Link, Bandar Seri Begawan BE 1410, Brunei Darussalam; Present address: Alexander von Humboldt Biological Research Institute, Calle 37 #8-40 Mezanine, Bogotá DC, Colombia
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  • John Grace

    1. Institute of Ecology and Resource Management, The University of Edinburgh, Darwin Building, Mayfield Road, Edinburgh EH9 3JU, UK;
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Author for correspondence:Sandra Patiño Fax: + 57 1 288 9564 Email: spatino@humboldt.org.co

Summary

  •  The giant flowers of the parasitic Rafflesia occur in the shade of the forest understorey. They present several characteristics in common with the related species, Rhizanthes lowii, which is a strongly endothermic flower. The possible existence of endothermy in Rafflesia tuan-mudae was investigated here.
  •  The internal and surface temperature of the flowers were continuously monitored with fine thermocouples while radiation fluxes and microclimatic variables were recorded. A computational fluid dynamic model was used to predict the concentrations of CO2 inside the diaphragm of the flower.
  •  It was found that the internal parts of the flower were maintained a few degrees (1–6 K) above air temperature. It was not possible to account for this temperature rise without postulating a significant internal source of heat. It was concluded that R. tuan-mudae is an endothermic flower that generates a maximum of 50–60 W m−2 of heat in the centre of the column.
  •  The possible role of endothermy, CO2 and volatiles as elements in the mimicry of the flower to attract pollinating blowflies is discussed and compared with the related species Rhizanthes lowii.

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