How genetically diverse are ex situ collections of rare and endangered plant species? It is important to understand the genetic diversity held by ex situ collections and develop tools and techniques to increase this diversity wherever possible. This is important because ex situ collections that are not genetically diverse are of limited value to the long-term conservation of the species. We are working with collaborators across the country to use molecular genetics to understand how effectively the genetic diversity found in wild populations of threatened species is captured in ex situ collections. We have worked with a threatened cycad from Belize (Zamia decumbens), a threatened oak species native to to the southeastern United States (Quercus gergiana), and a criticially endangered species from Hawai'i (Brighamia insignis). These results will be used to help conservation scientists build more genetically diverse ex situ collections for these species and related species, and will also be useful to inform any future reintroduction efforts for these species (Fant, Kramer, and outside collaborators).