Sula Vanderplank, Pedro Arce, César García Valderrama, Alan Harper, and Jonathan Snapp-Cook
Earlier this month several friends of Terra Peninsular set out to document a new report of the Mexican flannelbush (Fremontodendron mexicanum Davidson) from Valle de las Palmas, southeast of Tijuana. The authors, following a report of the plant from Dr. Alejandro Rodriguez (independent consultant) and Dr. Maria Chavez Perez-Banuet (Architecture Coordinator at Universidad Autónoma de Baja California (UABC) Valle de las Palmas), set off in search of the new population. The Mexican flannelbush, also known as “palo florido” is a striking tall shrub with large yellow flowers. In Mexico it is listed on the Norma Official 059 as an endangered species and in the United States it is listed as federally endangered. This new population is the third known occurrence in the world, and prior to 2004 less than 100 individuals of this beautiful shrub thought to survive in the wild.
Fremontodendron es una de las plantas más carismáticas y en mayor peligro en la Península de Baja California. Foto por Dr. Alan Harper
Although plants are historically reported from 10 localities globally (all in southwestern California and northwestern Baja California), most of these occurrences have been discounted either because the plants were of cultivated origin or because the plants can no longer be found. Currently, we believe there are only three known locations of Mexican flannelbush. As of two years ago, the only known surviving population in Mexico was in a deep canyon near San Vicente. Sadly a cattle dam was built upstream in 2005 which restricted the water reaching these plants, and in 2010 only two plants could be found alive in this canyon. The majority of known individuals of this species are found on Otay Mountain, a short distance north of the US/Mexico border. Recent field trips to explore the canyons of Otay Mountain have led to the documentation of approximately 3,000 individual plants growing in three of the canyons on Otay Mountain (see the 2009 US Fish and Wildlife Service 5 year status review for more information).
A two-hour hike west of UABC up a steep mountain led us to the hillsides where the flannelbush grows. We counted approximately 200 plants, but we did not have time to explore adjacent canyons or to complete an exhaustive census. The area where the new population was found had burned in the fall of 2010. Compared to the burn on Otay Mountain in the fall of 2003 that burned through the populations of Mexican flannelbush, the burn on this mountain was less intense. On Otay Mountain all of the above ground flannelbush were burned and the plants that regenerated were either seedlings or resprounts. On this mountain in Mexico, most of the Mexican flannelbush had only been partially burned and new growth was coming out of the existing trunks. Several large individuals were in full bloom on the hillside west of the University and we were able to make herbarium specimens with fruits, flowers and leaves.
The surrounding plant community can be identified as Chaparral, the companion plants found surrounding the Mexican flannelbush included Comarostaphylos diversiflora, Xylococcus bicolor and Eriodyction californicum, also resprouting were good numbers of Adenostoma fasciculatum and Artemisia californica. Beautiful specimens of Matilija Poppy (Romneya trichocalyx) were also found downhill. We can only imagine that before the recent fire this was much denser Chaparral which would have made our trek a more significant challenge. Lobbying is now being done to protect this important stand of Mexican flannelbush and the Contralor in charge of the UABC Valle de las Palmas unit was very interested this discovery.
The lack of knowledge about our native species remains a serious conservation challenge both locally and globally. To adequately protect our endangered native plants we must know where they occur, and more about their ecology. The ongoing efforts of Terra scientists and our partners to document the native plants of Baja California are part of our mission to create a greener and more sustainable future for everyone. The discovery of a third population of Mexican flannelbush, which is of a substantial size and appears to be healthy, gives us hope for the future of this species, and hope that perhaps many other rare plants still find refuge in unexplored regions of the Baja California peninsula.
More information about Fremontodendon mexicanum, its relatives and their cultivation can be found here.