The Kaibab bladderpod (Physaria kingii ssp. kaibabensis) is a small species in the Mustard Family that is endemic to the North Rim area of the Kaibab Plateau. As can be seen in the photo above, sometimes the plants can be less than one centimeter in size!
This plant has tiny, cream colored flowers and when seeds form the capsules are spherical, giving it the common name “bladderpod”. It is related to the more common Physaria kingii, but that species has bright yellow flowers and can grow a bit larger.
Habitat area of open meadow
Kaibab Bladderpod transect example
We are monitoring this rare species for a project funded by Section 6 of the U.S. Fish and Wildlife Service. The Arboretum has established four demography transects to keep track of population sizes and health.
Kaibab bladderpod flowers in the early spring (sometimes flowering even before the area is open to travel after winter closures). We were able to set up our transects in May 2025, and will repeat our monitoring each year in May to gather our data.
The populations do occur in the area that was burned by the Dragon-Bravo wildfire of August 2025, so we got our data right before that happened. We also were able to make conservation collections of seed for the species. We will be able to see if the transects were affected next spring, but it is likely the burn didn’t severely affect them because they occur in the open meadow habitat rather than under the trees.
If the fire burned them it is likely it was a fast-moving burn and who knows, maybe could affect the populations in a positive manner? Fingers crossed, we shall see come May 2026.
Sheila C. Murray is the Conservation Botanist at The Arboretum at Flagstaff.
