ABSTRACT Simpson’s memoir Understory: A Life with Trees illustrates significant changes in life writing that align it with transmodernity and its turn to the relational. They become apparent when reading Understory alongside Édouard Glissant’s distinction between root identity and relation identity. In generic terms, the memoir confirms the growing openness to different conventions, in this case those of the botany treatise and the nature essay. Moreover, the work expands limits on a thematic level by foregrounding Simpson’s affinity with trees, a true map of her story of living in a forest in Queensland for ten years. With this other-than-human perspective, Simpson reveals the interpenetration between the two types of identity theorised by Glissant, opting for a complex relational view that does not rule out roots. This paper argues that Simpson has made a number of important discoveries: 1. trees are at the same time rooted and relational; 2. her form of environmental activism requires readjustment; 3. she needs to undo the latinising of botany terms and learn the Indigenous names of trees before she can learn the language of the forest; 4. human exceptionalism and anthropocentrism have to be put in perspective; and 5. lone trees grow taller but die younger.