One acorn produces two seedlings in Chinese cork oak Quercus variabilis.

Although the early germination of white oaks has long been considered an adaptation to counter animal predation, the role of the robust radicles of white oak acorns has been largely neglected in the interaction between acorns and seed-eating animals. Here, the regeneration capabilities of the pruned radicles of intermediate oak Quercus variabilis left by the acorn-eating animals were compared to test the 'one acorn produce two seedlings' hypothesis stating that the remnant radicles exhibit the capability to produce normal seedlings owning to their atypical nutritional and anatomical characteristics. Our results first showed that both pruned radicle and cotyledons from single acorn successfully established seedlings, providing strong evidence on an old puzzle that the robust radicles of early-germinating oak acorns act as reserved propagules, allowing them to escape animals' predation. Our study also suggests that much of the investment in the food reserves of an acorn may be important as a food reward for the animals that disperse the acorns, rather than simply serving as energy for the young seedling.