Distribution of Flower Pigments in Perianth of Cattleya and Allied Genera

Abstract

The 68 species sampled, representing 11 genera of the Subtribe Laeliinae, were classified into 9 groups on the basis of the distribution of carotenoids and anthocyanins in the epidermal and parenchymatous tissues of the petals. Yellow and orange flowers contained carotenoids in one or both tissues, while in red and purple flowers carotenoids and anthocyanins were both present, although not necessarily in the same cell layer. A Hunter's diagram of the colour chromaticity of the petals was divided into 3 sections according to hue. In the first section (yellow or orange petals), the b/a value (a measure of hue) was >0.47 due to the carotenoid pigments, in the second section (red flowers), it was between 0.47 and - 0.13, and in the third section (purple/red 'orchid tone' flowers), it was between -0.13 and -1.0. In petals containing carotenoids, increased chromas corresponded to greater brightness, but when anthocyanins were present increased chromas corresponded to reduced brightness. The size and shape of the upper epidermal cells of the petals and lips varied with the species. These cells were smaller and more square in glossy-flowered species, and larger and more triangular in species with velvety-textured flowers. Species with large, showy flowers, such as Cattleya labiata, Laelia purpurata and Brassavola digbyana, had the largest and longest epidermal cells.