Water-impermeable seeds have structures (“water gaps” or lens 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.