“Plant blindness” is affecting humans' relationships with plants, which has negative consequences for both science and conservation. It is, therefore, important to find new ways to promote societal interest in botany and plants. One possibility is encouraging the use of informal settings to promote curiosity and provide education to students. Forest fragments can be regarded as open air labs for teaching botany, especially on university campuses. We aimed to formally document the angiosperm diversity in the Mata dos Saguis (MS), a fragment of Atlantic forest under restoration belonging to the central campus of the Federal University of Rio Grande do Norte (UFRN), Brazil. We recorded 140 species, 113 genera in 52 families, and 24 orders of angiosperms. The MS has nearly 10% of the species and one third of all the families occurring in the entire state of Rio Grande do Norte, representing the main evolutionary groups of angiosperms, and we also recorded two new species occurrences for the state. Here we provide a checklist of the MS, a location that has been used as an open-air laboratory by many UFRN undergraduate courses in biosciences. We also share examples that can be replicated in other institutions and discuss the process of learning systematic botany in floristically rich countries by means of alternative and hands-on experiences.