Integrating fruit and seed traits to support the conservation of the threatened tree Stephanopodium engleri.

The endangered tree species Stephanopodium engleri Baill., endemic to the semideciduous seasonal forest of the Quadrilátero Ferrífero in Brazil, is threatened by its limited distribution and loss and degradation of its habitat. The objective of this study was to characterize the fruits, seeds, and germination traits, providing support for the development of effective conservation strategies. A biometric analysis of 300 fruits revealed that the species produces bilocular drupes, although approximately half of the fruits contain only a single seed. Anatomical studies demonstrated the presence of a fibrous seed coat, which is more permeable at the hilum and helps to regulate water uptake. The germination trials revealed that fresh seeds had a 92% germination rate and a rapid germination time, averaging 12 days when tested at 25 °C. However, the seeds lost viability entirely after 90 days of storage, along with significant water loss, which is indicative of recalcitrant seed storage behavior. The abundance of reserves, including starch, proteins, and lipids in the cotyledons, promotes rapid initial growth and supports seedling establishment. These findings indicate that S. engleri depends on immediate germination and quick seedling growth for survival, with sensitivity to dry conditions possibly limiting its range to moist, intact forest patches. The results emphasize the species’ reliance on specific environmental factors for regeneration and highlight the difficulties in ensuring its long-term conservation.