It is difficult to imagine a world without colour. We see, think and even dream in colour. Colours influence human attire, diet and mood. It is widely believed to be a good indicator of our attitude. Knowingly or otherwise, we rely on colour for routine activities; are guided by colours and occasionally avoid specific colours! Whatever it is, we take a colour for granted.

However, there is more to colour than what meets the eye. Colour is a complex phenomenon. Although we may see a flower red; there is nothing ‘red’ in flower. Similarly, there is nothing blue in these characters, yet we see it, blue.  Colour is a perception rendered in the brain of an observer. Although the physical basis of the underlying process of reflection of the electromagnetic waves is robust, colour perception is governed by the spectral sensitivity of the observer. What we perceive green may be seen differently by insects and birds. Undoubtedly, colour vision capability would have had played a decisive role in the evolutionary success of species.

Floral radiometry acts as a connecting link between colour science and plant ecology. It integrates hyperspectral remote sensing, plant, and colour science and attempts a quantitative representation of floral colours. Functionally, flowers are reproductive structures of plants, which use the colourful display to attract pollinators. From an organic point of view, the perception of flower colour by pollinators are more critical to the plant than human appreciation. Floral radiometry seeks to represent floral colours from pollinator (insect and bird) visual perception.

This book begins with an introduction to the electromagnetic spectrum, followed by an overview of the human visual system and basic concepts of colour. The mid-section comprises of colour models, the International Commission on Illumination (CIE), colour representation and colour difference measurements. The concluding chapters discuss the pollinator vision and colour perception. The last chapter illustrates temporal changes in floral colours in the framework of human and insect pollinator perception.

This edition primarily serves to introduce Floral Radiometry to researchers and draw the attention of science administrators and policymakers. The authors believe the intricate labyrinths of floral colours, conceal new insights, to be discovered. Our belief stems from the statement “If floral displays were only to ensure successful reproduction, why should asexually reproducing plants invest heavily in the energy-intensive process of flowering?”