Reproductive Ecology of Physaria kingii Subsp. Kaibabensis, an Endemic Species of the Kaibab Plateau, USA

Physaria kingii subsp. kaibabensis, the Kaibab bladderpod (Brassicaceae), is endemic to the Kaibab Plateau, in Coconino County, Arizona. Due to its limited distribution, state and federal agencies are concerned about its conservation status. However, limited information is available regarding the ecology of this species. To better understand several aspects of its ecology, in 2015 and 2017 the following parameters were assessed at six sites: plant density, habitat assessment (characteristics/disturbances), reproductive ecology (pollination biology, reproductive output, and flower visitors), pre-dispersal seed predators, and seed germination. Overall we found that plant density and habitat characteristics/disturbances varied across time and among sites for Physaria kingii subsp. kaibabensis. In addition, this species requires pollinators for fruit and seed production. At the site level, fruit set, seed set, and seed germination, can be up to 73%, 39%, and 93%, respectively. Also, evidence was found for the presence of pre-dispersal seed predators and gall formers. These studies provide much-needed information to assist with the conservation and management of this endemic species and will assist the US Fish and Wildlife Service with any future listing decisions for the species.