Accurately describing the ecological relationships between species is more than mere semantics–doing so has profound practical and applied implications not the least of which is that inaccurate descriptions can lead to fundamentally incorrect predicted outcomes of community composition and functioning. Accurate ecological classifications are particularly important in the context of global change where species interactions can change rapidly following shifts in species composition. Here we argue that many common ecological interactions–particularly competition and parasitism–can be easily confused and that we often lack empirical evidence for the full reciprocal interaction among species. To make our case and to propose a theoretical framework for addressing this problem we use the interactions between lianas and trees whose outcomes have myriad implications for the ecology and conservation of tropical forests (e.g. Schnitzer et al. 2015).