In the unfolding debate on the prospects, challenges and viability of the imminent transition towards a ‘Bio-Based Society’ or ‘Bio-based Economy’—i.e. the replacement of fossil fuels by biomass as a basic resource for the production of energy, materials and food, ‘big’ concepts tend to play an important role, such as, for instance, ‘sustainability’, ‘global justice’ and ‘naturalness’. The latter concept is, perhaps, the most challenging and intriguing one. In public debates concerning biotechnological interactions with the natural environment, the use of (...) terms such as ‘nature’ and ‘naturalness’ is both inevitable and hazardous . Indeed, various conflicting interpretations of naturalness play a role on both sides of the current debate. This paper aims to analyse and critically assess the role of ‘nature-speak’ in the BBS transition. We will begin with a concise overview of the vicissitudes of the nature-concept so far, focussing on how modern science and technology have challenged and affected our understanding of what nature is. Subsequently, we describe how ‘naturalness’ functions in the unfolding BBS debate. Finally, we will focus on a particular case study, namely the production of rubber with the help of natural latex coming from dandelion plants rather than from rubber trees. On the one hand, this is presented as a more natural and nature-friendly way of producing rubber. On the other hand, it is a sophisticated process, involving high technology and primarily focussed on competitiveness on the global market. To what extent or in what sense can dandelion latex be regarded as more natural? And what can we learn from this case study when it comes to addressing naturalness in the broader conceptual and bio-political arena? (shrink)