Breaking the norm: Absence of seed size/seed number trade‐off in Hymanaea stigonocarpa, a tree species from the Brazilian semi‐arid

Abstract The seed size/number trade‐off is a central topic in plant biology, reflecting key functional traits that affect plant distribution and abundance. Despite theoretical and experimental evidence supporting this trade‐off, it can be influenced by local variations in resource availability. We investigated the seed size number trade‐off in a multiple‐seeded perennial tree ( Hymanaea stigonocarpa ) at the individual plant and fruit levels. This plant species is endemic to the Brazilian semiarid, occurring on soils with low levels of water and nutrient availability. Both the mean seed and fruit mass per plant showed a positive relationship with plant size but were not affected by seed number nor by fruit number, respectively. The absence of a trade‐off mass/number of seeds and fruits is probably related to the low number of fruits produced by H. stigonocarpa : abortion of self‐pollinated pistils and flowers regulates the fruit number, ensuring greater availability of resources for fruits and seeds of allogamous origin. The mean seed mass per fruit was not affected by the number of seeds per fruit but showed a positive relationship with fruit mass excluded seeds. The interaction between seed number and fruit mass indicates that fruits with lower seed number and higher mass should produce larger seeds. These results suggest the existence of asymmetric competition only between seeds that develop into small fruits. Overall, this study suggests that the production of smaller number of large seeds may be a strategy for seedling establishment of this species under low nutritional and water availability conditions in the Brazilian Cerrado.