First Report of Viviparity in Seeds of the Physically Dormant Species Hymenaea martiana (Fabaceae)

Viviparity is rarely reported in species with seed physical dormancy. This is because physical dormancy, common in tropical trees, results from the impermeability of the seed tegument to water and regulates the timing of germination. Records of germination within the fruit in such species suggest greater functional plasticity than traditionally assumed. This study reports and quantifies viviparity in Hymenaea martiana seeds over four consecutive years (2019–2022) and assessed seed dormancy status through vigor tests. Sixty fruits were collected annually, and viviparity was estimated as the proportion of fruits containing at least one seed with radicle protrusion. Non-viviparous seeds were subjected to emergence tests with and without mechanical scarification, and cumulative emergence, percentages of dead and water-impermeable seeds, and seed water content were evaluated. Viviparity occurred consistently, affecting approximately 10–15% of the fruits, with no significant differences between years, indicating that the phenomenon was not associated with extreme environmental events. However, early germination did not result in seedling establishment because the emerging roots dehydrated while still inside the fruit. Mechanical scarification significantly increased emergence, confirming the presence of seed physical dormancy. These results show that, although viviparity was observed recurrently in the studied population of H. martiana, seed physical dormancy remains the main mechanism controlling germination in this species.