Representing and encoding plant architecture: A review

A plant is made up of components of various types and shapes. The geometrical and topological organisation of these components defines the plant architecture. Before the early 1970's, botanical drawings were the only means to represent plant architecture. In the past two decades, high-performance computers have become available for plant growth analysis and simulation, triggering the development of various formal representations and notations of plant architecture (strings of characters, axial trees, tree graphs, multiscale graphs, linked lists of records, object-oriented representations, matrices, fractals, sets of digitised points, etc.). In this paper, we review the main representations of plant architecture and make explicit their common structure and discrepancies. The apparent heterogeneity of these representations makes it difficult to collect plant architecture information in a generic format to allow multiple uses. However, the collection of plant architecture data is an increasingly important issue, which is also particularly time-consuming. At the end of this review, we suggest that a task of primary importance for the plant-modelling community is to define common data formats and tools in order to create standard plant architecture database systems that may be shared by research teams.