Temperature distribution in light-coloured flowers and inflorescences of early spring temperate species measured by Infrared camera

Temperature is a limiting factor for plant reproduction under harsh conditions. Using an infrared camera, we studied temperature distribution in three early flowering light-coloured species of markedly different morphology. The influence of three environmental factors (temperature of the ambient air, temperature of the ground and irradiance) on the temperature of the flowers and inflorescences was evaluated. White petals and yellow centres of sun tracking Anemone nemorosa (Ranunculaceae) were shown to be on average 1.6 and 3.4 °C warmer than the ambient air, respectively. The surface temperature of the sun lit yellow discs of Bellis perennis (Asteraceae) was on average 7.4 °C warmer than the ambient air. Direct solar light was found to be responsible for large temperature differences between the discs and the marginal ray flowers. Bell-shaped white flowers of Galanthus nivalis (Amaryllidaceae) bent to the ground were on average 2.7 °C cooler than the surrounding air. The temperature relations of the different reproductive organs to the studied environmental factors are discussed. Temperature behaviour of the studied lowland species is compared with the results previously gained for alpine and arctic species by other authors. Ecological importance of our conclusions is considered.