Small stature, long life: Radiocarbon evidence of longevity in an endemic rupestrian grassland subshrub of the Brazilian Savanna

Rupestrian grasslands are ancient, biodiverse, fire-prone ecosystems primarily found in Brazil's highlands. The longevity of small woody plants in these habitats remains poorly understood, largely because persistent belowground organs (xylopodia) are rarely dated directly. We investigated this structure in Camarea ericoides (Malpighiaceae), a small Brazilian Savanna subshrub, using a multi-proxy approach that combined wood anatomy, scanning electron microscopy, X-ray densitometry, ring counting, and bomb-pulse radiocarbon ( 14 C) dating. The xylopodium showed distinct growth layers marked by semi-ring-porous wood, small vessels, and marginal parenchyma bands, along with radial variation in wood density. Ring counting identified 40 growth layers, indicating an average radial growth rate of 0.425 mm year⁻¹. However, 14 C dating showed that the individual was at least 51 years old, revealing that ring counts underestimated age by 11 years, probably due to missing, indistinct, or locally absent rings. Although based on a single individual, this independently validated estimate establishes a previously unknown minimum longevity threshold for C. ericoides and suggests that small xylopodium-bearing subshrubs may achieve multi-decadal belowground persistence. In summary, our findings show that small endemic xylopodium-bearing subshrubs can preserve hidden demographic legacies for more than half a century. This highlights the need to consider belowground woody organs when assessing persistence, recovery potential, and conservation value in fire-prone tropical open ecosystems.