RSABG currently has five living plants from two accessions growing in the garden: Acc. 14425; cuttings collected in wild 1980; San Diego County: San Ysidro Mountains; 1 plant Acc. 15463; cuttings collected in wild 1986; San Diego County: San Ysidro Mountains; 4 plants

Active propagation continues in the nursery at RSABG. In 2016, both softwood and semi-hardwood cuttings of Acc. 15463 were propagated by stripping off trichomes by hand and dipping in a 10% dilution of Wood's Rooting Hormone. In 2016, 20 plants were propagated from seed of Acc. 23212 using a hot water treatment and a cold-moist stratification.

he Seed Conservation Program at RSABG currently houses four seed collections of Fremontodendron mexicanum: Acc. 16824; 1985; Baja California: Maneadero; 21 seeds Acc. 15783; 1988; San Diego County: San Ysidro Mountains; 543 seeds Acc. 19682; 1997; San Diego County: San Ysidro Mountains; 67 seeds Acc. 23212; 2010; San Diego County: San Ysidro Mountains; 2276 seeds

San Diego Zoo Global has two maternal line seed collections. One collection was made from the smallest population in Little Cedar Canyon in 2016. The other was made from the largest population in Woodwardia Canyon in 2017. We plan on collecting from the third and final population in Cedar Canyon in 2018.

Based on an September 2020 extract of the California Plant Rescue Database, San Diego Zoo Global holds 4 accessions of Fremontodendron mexicanum in orthodox seed collection. There are as many as 19464 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 4 accessions of Fremontodendron mexicanum in orthodox seed collection. There are as many as 2907 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

Based on an August 2020 extract of the California Plant Rescue Database, San Diego Zoo Global has collected 4 seed accessions of Fremontodendron mexicanum from 3 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 243 maternal plants

Based on an August 2020 extract of the California Plant Rescue Database, California Botanic Garden has collected 4 seed accessions of Fremontodendron mexicanum from 2 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 50 maternal plants

San Diego Zoo Global has two maternal line seed collections. One collection was made from the smallest population in Little Cedar Canyon in 2016. The other was made from the largest population in Woodwardia Canyon in 2017. We plan on collecting from the third and final population in Cedar Canyon in 2018.

The US Fish and Wildlife 5-year review (USFW 2009) indicates that there are 3 populations in the US, occurring in 3 separate canyons, all on the north slope of Otay Mountain. The total number of individuals is roughly 6,000 individuals. The numbers appear stable, and in my opinion appear to be growing. In surveying I have seen many young trees and the populations seem to be doing well. That being said, they are all very localized, with all individuals occurring in roughly 11 square miles, and the threat of a single fire damaging all populations is great.

Study published in 2014 by BC Austin with SDSU discussed the reproductive biology of the species, including pollinators, pollination success, seed dispersal, and germination success. European honey bees were the predominate floral visitors, though native bees were present. The seeds are dispersed by seed harvesting ants, and potentially by flowing water. Heat treatment the most successful pre-treatment in germination. See References below for citation, PDF available online.

Some introductions have taken place on the San Diego Natural Wildlife Refuge. Multiple individuals were planted in two separate locations. Neither introduction was very successful, though it is thought that they were unsuccessful as a result of the extreme prolonged drought that occurred in Southern California from 2011-2016. I believe that there are still several living individuals in the introductions. John Martin with the SDNWR has more information.

The other major threat is the spread of invasive species that specialize in the rocky washes where Fremontodendron thrives. I have concern with the spread of Tamarix spp. which are prevalent in the washes, as well as Foeniculum (fennel) and many different grasses. 

Invasive weed removal in the canyon washes is also needed. Though difficult to access, the removal of Tamarix spp. and other invasives, will ensure the species is able to spread and potentially minimize the bio-load and fire risk.

We must first ensure that the breadth of the species genetic information is stored ex-situ. Research should then look at reintroduction methods.

All 3 populations occur on protected lands. Populations are monitored periodically, but are difficult to access. Some weed removal is done in some areas, but as they are so hard to access, it is minimal.

There are also two historic occurrences of the species in Mexico. The populations are believed small, and one may be extirpated.  Very little information is available.

The greatest threat to the species, in my opinion, is an increased fire frequency, as a result of invasive species. The 3 populations are in close proximity to one another and are very remote. A single large fire around Otay Mountain could threaten all known wild individuals. The species is adapted to fire, and is able to re-sprout after most fires. Invasive grasses have led to a greater intensity of fires, potentially resulting in fires that are so hot that the roots are destroyed and can no longer re-sprout. More problematic is the increase in fire frequency as a result of invasive grasses. Repeated burns in short succession can potentially decimate the populations in a very short amount of time.

The Seed Conservation Program at RSABG currently houses four seed collections of Fremontodendron mexicanum:

• Acc. 16824; 1985; Baja California: Maneadero; 21 seeds
• Acc. 15783; 1988; San Diego County: San Ysidro Mountains; 543 seeds
• Acc. 19682; 1997; San Diego County: San Ysidro Mountains; 67 seeds
• Acc. 23212; 2010; San Diego County: San Ysidro Mountains; 2276 seeds

Active propagation continues in the nursery at RSABG.
In 2016, both softwood and semi-hardwood cuttings of Acc. 15463 were propagated by stripping off trichomes by hand and dipping in a 10% dilution of Wood's Rooting Hormone. 
In 2016, 20 plants were propagated from seed of Acc. 23212 using a hot water treatment and a cold-moist stratification. 

RSABG currently has five living plants from two accessions growing in the garden:

• Acc. 14425; cuttings collected in wild 1980; San Diego County: San Ysidro Mountains; 1 plant
• Acc. 15463; cuttings collected in wild 1986; San Diego County: San Ysidro Mountains; 4 plants

Fremontodendron mexicanum is known with certainty only from southern San Diego County, California and south into Arroyo Seco (North of San Quintin) Baja California, Mexico. The plants have been relocated recently at only one of the twelve known sites despite searches of at least some of the historic locales. The California population is thought to contain fewer than one hundred individuals. The Bureau of Land Management specifically manages its land for this population; the Area of Critical Environmental Concern and the Research Natural Area, on which about 50% of the plant's habitat lies, were designated for the preservation of F. mexicanum. The species is likely susceptible to adverse genetic effects due to the low number of remaining individuals. Another primary threat is from altered fire regimes.

Competition for water with an annual ryegrass that was introduced by the Department of Forestry after a fire. Alteration of fire natural fire patterns is a threat to seedlings, seed banks and regrowth (USFWS 1998).

Less than 100 individuals are known from sites in San Diego County and Mexico. Reports of individuals growing in Los Angeles County are believed to be garden escapees (USFWS 1998).

The remaining population in San Diego County is under the protection of the Bureau of Land Management (BLM), however, BLM does not have control over the entire habitat. Efforts to control human foot traffic (a potential source of accidental fires) have not been successful (USFWS 1998).

Remaining populations are on privately owned land that need protection. In addition to better understanding the fire effects, research needs include reproductive biology and ecology.