Landmark and outline methods in describing petal, sepal and labellum shapes of the flower of Mokara orchid varieties

Together with petal color and other floral characteristics, petal shape and size vary widely within Mokara orchids. An appropriate understanding of their flower forms is fundamental and necessary for the improvement of this economically and aesthetically important plant. This study was therefore conducted to describe variations in the flowers of Mokara with emphasis on the shapes of sepals, petals and labellum using geometric morphometric (GM) methods based on summarized information about contours of the structures. We specifically applied the truss-network based analysis of landmarks and the elliptic Fourier method in describing the petal and sepal outlines. Each of the methods required a dimension reduction technique in the form of principal component analysis to summarize independent shape characteristics. Results showed that classification and discrimination of the varieties based on the shapes of the petals and sepals could be achieved using both techniques.