Photo Walk Around the World: North American Southwest - Mexican fencepost

Mexican fencepost cactus

Pachycereus marginatus (Lophocereus marginatus)

The Mexican fencepost cactus is a tall columnar cactus native to the states of Hidalgo, Queretaro, and Guanajuato of Mexico. As the common name suggests, it is widely used as a natural barrier or “living fence”. The columns can grow up to 20 feet tall at maturity. Each column has 5-7 ribs that create an accordian-like perimeter which alternately folds and protrudes away from the center. The protruding ridges on the column are lined with stubby white to tan spines on juvenile growth. Mature growth produces both shorter spines and pink to red colored 1.5 inch-long tubular flowers. When pollinated, the flowers develop into yellow-to-red colored fruit that line the body of the plant in rows along the ridges at the end of Spring. 

The plant can be vegetatively propagated by slicing a section of the column off, allowing it to suberize (dry out) at the cut site, and then submerging the cut section into moist potting mix until roots develop. P. marginatus has been in traditional medicine by the people of Zapotitlan for gastrointestinal issues by peeling and boiling sections of the column and ingesting orally. It is also known to have been used as a diabetes treatment in traditional medicine. Additionally, within Western modern medicine, P. marginatus has been researched for its promise as a treatment of gastrointestinal cancers. In one study, conducted on tumor-bearing mice, the extracts from the cacti produced up to 89% in vitro cytotoxicity to L5178Y-R cancer-causing cells, supporting the future evaluation of the extracts as bioactive compounds within clinical-level studies.

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