Abstract
Leaf shape is a key plant trait that varies enormously. The diversity of leaf shape, and the range of applications for data on this trait, requires frequent methodological developments so that researchers have an up-to-date toolkit with which to quantify leaf shape. We generated a dataset of 469 leaves produced by Ginkgo biloba, and 24 fossil leaves produced by evolutionary relatives of extant Ginkgo. We quantified the shape of each leaf by developing a geometric method based on elastic curves and a topological method based on persistent homology. Our geometric method indicates that shape variation in modern leaves is dominated by leaf size, furrow depth, and the angle of the two lobes at the base of the leaf that is also related to leaf width. Our topological method indicates that shape variation in modern leaves is dominated by leaf size and furrow depth. Both methods indicate that there is greater diversity in the shape of fossil leaves compared to modern leaves. The two approaches we have described can be applied to modern and fossil material, and are complementary: identifying similar primary patterns of variation, but revealing some different aspects of morphological variation.
Competing Interest Statement
The authors have declared no competing interest.