The commercial trade of propagated listed plants is a common but controversial ex situ conservation approach for rare plant species. We investigated the Internet trade of plants protected under the U.S. Endangered Species Act to determine their availability for interstate (i.e., regulated) commerce. We identified 49 listed plant species that were available via the Internet, with less than 10% of vendors having obtained the required federal permit. The lack of permits among vendors suggests that sellers are unaware or ignore regulations. Illegal trade undermines both the permitting process and conservation efforts of the U.S. Fish and Wildlife Service to ensure that commercial propagation aids the long-term survival of listed species. Furthermore, in addition to supplying a demand for plant collections and landscaping, commercial trade could provide a source of plants for deliberate species introductions, including assisted colonization—a debated conservation strategy that involves moving species to new environments to mitigate for habitat loss and climate change. Given the potential costs and benefits associated with trade, the challenges suggest that a collaborative approach between agencies, nurseries, and plant collectors is needed to regulate the trade of listed plants. In regulating commercial trade, policymakers and conservation biologists may want to consider potential risks and benefits of private efforts to recover species.