The reflectance spectrum of three yellow flowered species (Encelia californica, Encelia farinosa, and Spartium junceum), all grown on the coast of California, was tested to determine if reflectance among the yellow flowers was significantly different. It was hypothesized that there would be a significant difference in reflectance in the 400-700 nm wavebands for the three different species of flowers which all possess yellow petals. Using a Unispec Spectral Analysis System to obtain reflectance spectra for 12 yellow petals of three flowered species, a custom index was created in order to observe differences in the yellow color of the petals, which may account for pollinator attraction and possible natural selection based evolution (N. M. Waser et. al. 1983). The index accounted for a specific range of visible light from approximately 600-700 nm, where the largest reflectance differences occurred among the three tested species. Based on the obtained measurements of the 36 different flower reflection spectra, it was observed that the reflectance for the three different species of yellow flowers was significantly different for not only the created Mariam-Valerie Index, MVI, but also for the Normalized Difference Vegetation Index, NDVI, as well. This difference among similar species may have biological importance, as this significance may account for natural selection based evolution of the flowers which could include specific pollinator selection and increased survival of these particular plants among other yellow flowered species.
Fam, Mariam E. and Espinoza, Valerie E., "Using the Unispec to Test the Difference in Reflectance of the Yellow Petals of Encelia californica, Encelia farinosa, and Spartium junceum" (2013). Pepperdine University, All Undergraduate Student Research. Paper 67.