Water-impermeable seeds with physical dormancy have structures (“water gaps” or lenses in legumes) for detecting environmental cues that cause them to become water-permeable (nondormant). physical dormancy is common in legume species, whose seeds may have a visibly-demarcated structure called the pleurogram.
Rodrigues-Junior et al. update the occurrence of the pleurogram in plant taxa and show for the first time that it can function as a water gap. An opened pleurogram creates a wider opening than an opened lens, and the pleurogram may function as a water gap in a large number of leguminous species.
Rodrigues-Junior, A. G., Mello, A. C. M. P., Baskin, C. C., Baskin, J. M., Oliveira, D. M. T., & Garcia, Q. S. (2018). A function for the pleurogram in physically dormant seeds. Annals of Botany, 123(5), 867–876. https://doi.org/10.1093/aob/mcy222