Leaf margins as sequences: A structural approach to leaf identification

•We propose a high-level interpretation of leaf contours through CSS analysis.•Leaf margins are described by an original string representation of vectorial symbols.•Methods inspired from string processing are adapted to this objects.•We use this spatially-rich descriptor to perform species classification.•Performance is compared with state-of-the-art shape descriptors, and shows competitive results.

In the context of an automated leaf identification process, the use of thorough leaf margin descriptors is essential given the importance of this criterion in the determination of the species. The spatial properties of teeth along the leaf contour are something to keep track of, which is made possible through the use of structured representations. This paper introduces a sequence representation of leaf margins where teeth are viewed as symbols of a multivariate real valued alphabet. It presents the methods developed to make use of this description for classification and implementation in a mobile tree identifying application. The results of various classification methods are compared and discussed, both in terms of species recognition and of consistency with botanical concepts.