Volunteers play a major role in growing Pepperwood’s Stephen J. Barnhart Herbarium, which provides documentation of the vascular plants found across the preserve. In addition, the collection of non-vascular plant species such as mosses and liverworts as well as lichens and fungi began in 2013. These collections provide an important baseline for studies of species presence, phenology and distribution, as well as an important data source for studies in ecology, genetics, systematics, phytogeography and evolution.
Pepperwood maintains a Flora guide, originally created by Greg de Nevers, resident biologist for the California Academy of Sciences during their ownership of the property. It is updated with new species and taxonomic revisions as needed.