Variability is a critical, but often overlooked driver of ecological interactions. Animals that interact with plants experience astoundingly high trait variability within plant individuals – both spatially among tissues and temporally through plant ontogeny and organ development. While this variability is often treated as mere noise, recent work finds that sub-individual variability can itself be heritable and can influence interactions with consumers and mutualists, suggesting that variability at this scale could be a key phenotypic axis driving plant-animal interactions. In this session, we will explore cutting edge research on the causes and consequences of sub-individual variability in plant traits. Speakers in the session will discuss the major drivers of sub-individual trait variability; the effects of sub-individual variability on different types of biotic interactions, such as herbivory and pollination; and the potential for sub-individual variability to shape coevolutionary outcomes for both plants and animals. By uniting the mechanistic basis, ecological implications, and evolutionary role of this ubiquitous plant characteristic, this session aims to present a holistic view on the role of sub-individual plant trait variation in nature.