Cercocarpus traskiae

It is endemic to Catalina Island, one of the southern Channel Islands in Los Angeles County, California. It is known from just a single population,[1] found in Wild Boar Gully, an arroyo covered in coastal sage scrub on Catalina Island.[2] The steep sides of the arroyo contain soils of saussurite gabbro.[1][2]

It was rare when it was first discovered by Blanche Trask in 1897[3] or 1898,[1] when about 40[3] to 50[1] plants were counted.[2]

When it was federally listed as an endangered species, in 1996, there were only six mature plants remaining.[1] It has been called "one of the rarest shrubs in the continental United States"[3] and "one of the rarest trees in North America."[2]

Cercocarpus traskiae is a large shrub or tree that grows up to 8 meters in height. The leaves have thick, leathery oval blades with serrated edges and woolly-haired undersides. The leathery, woolly texture of the leaves distinguishes it from other Cercocarpus.[4] The inflorescence is a cluster of up to 10 flowers which do not have petals. Plants do not always flower each year.[2]

While there are sometimes many seedlings noted, the seedling survival rate and rate of recruitment are quite low.[2] As of 2007, there are only seven adult trees capable of reproduction, all located in Wild Boar Gully, and most of these are very old.[2]

The Catalina Island mountain mahogany is threatened by ungulates such as deer, and feral goats and pigs.[2] The goats have been removed from the island, and fencing has been placed to prevent the remaining animals from touching the plants.[2]

This rare species hybridizes with its relative, Cercocarpus betuloides, a situation that may lead to genetic swamping of the rare plant.[4] This hybridization may be made more likely by the animals' disturbance of the habitat.[2] Many of the seedlings and saplings growing today may be hybrids.[2]

The population of pure Cercocarpus traskiae is not increasing and the species is entirely dependent on human intervention today.[2][5]

• Chaparral
• California chaparral and woodlands

• Calflora: Cercocarpus traskiae (Catalina Island mountain mahogany)
• Jepson Manual eFlora (TJM2) treatment of Cercocarpus traskiae
• UC Photos gallery — Cercocarpus traskiae