ibclogo XVI International Botanical Congess

Abstract Number: 6192
Poster No. = 2583


GRAPHICAL MANIPULATION THAT STRAIGHTENS THE MIDVEINS OF LEAVES PROMISES TOIMPROVE THE CONSISTENCY OF MORPHOMETRIC MEASUREMENTS.


Nadia Talent and James E. Eckenwalder, Botany Department, university of Toronto, 25 Willcocks St., Toronto, Canada M5S 3B2


Asymmetry has confounded many attempts to derive quantitative comparisons of leaf shape from any but the simplest of measurements. One component of asymmetry appears to involved curvature of the midvein, and associated changes in the shape of the lamina. Leaf halves were pressed and their digitized outlines were transformed by rubber-sheeting" to force the midvein to a straight line. Results were assessed by using principal components of Elliptic Fourier harmonics from complete pseudoleaves. Clustering of related species improved. The effect differed from using Fourier amplitudes of unstraightened leaves, which can also improve the clustering of Fourier harmonics when asymmetry is a source of noise. A suite of Turbo Pascal programs that interface with MorphoSys (Meacham and Duncan 1993) and NTSYS-pc (Rohlf 1992) is available. The method is limited by the smoothness of the image, and is currently restricted to simple, unlobed, leaf shapes.

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