Open biomes such as grasslands, savannas, shrublands are associated with many global biodiversity hotspots, and cover ∼60% of land globally. Yet, extensive and increasing anthropogenic activities threaten their functioning and biodiversity. Here, we argue that, in open biomes, researchers and stakeholders (e.g., policy-makers, practitioners) should more comprehensively acknowledge that more than half of a plant's biomass is typically located belowground. Not only fine roots but different belowground coarse organs of plants (e.g., thick roots, rhizomes) play key ecosystem functions that have been largely neglected in basic and applied ecology. By more accurately accounting for the distribution of these organs along ecological gradients, their biomass turnover and decomposition rate, we would improve estimates of carbon cycling (core in climate change mitigation policies) as well as ameliorating conservation efforts focused on open biomes worldwide.