Relating Colorimeter Measurement of Plant Color to the Royal Horticultural Society Colour Chart

Communicating perceptions of color entails not only evaluation and description of colors by one individual but also the visualization by another of the colors described. Color charts have long played a unique intermediary role in this process. Visual color evaluation, however, is often flawed. The increased availability of portable color-measuring instruments now makes possible a more objective notation of specimen colors, and the method detailed here facilitates reference to the closest color chip in the Royal Horticultural Society Colour Chart. After surveying many color charts used by biologists for biological descriptions, Tucker et al. (1991) recommended using the Royal Horticultural Society (RHS) chart. They observe that the RHS chart was designed for horticultural taxa. (It does not, for example, sample extensively the color range of fungi.) I also recommend the RHS chart, but stress that color-evaluation technique is an essential and critical-though often neglected– aspect of color description. Careful color evaluation is desirable for botanical and horticultural descriptions. It is true that botanical descriptions commonly have not included detailed color references because, inter alia, color is not well preserved in most herbarium specimens. Some botanical exploration is, however, devoted to the search for plants with superior horticultural characteristics, including color. Moreover, though color may not supply important taxonomic distinctions among plants in a group as presently known, it may assume greater importance as new taxa are discovered. Both evaluating color and determining