Bark patterns are a visually important characteristic of trees, attributed to fractures caused by secondary growth of the trunk and branches. A detailed understanding of bark patterns has been impeded by insufficient information regarding biomechanical properties of bark and the corresponding difficulties in faithfully modeling bark fractures using continuum mechanics. Here we focus on grasstrees, which have an unusual bark-like structure composed of distinct leaf bases connected by sticky resin. Due to its discrete character, this structure is exceptionally well suited for computational studies. We created a dynamic grasstree model, which captures both the phyllotactic patterning of the leaf bases during primary growth and the emergence of fractures due to secondary growth. The model reproduces key features of grasstree bark patterns, including inhomogeneities due to compression of leaf bases at the sites of inflorescences.
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