Mexican Fence Post Cactus
Lophocereus marginatus
Family: Cactaceae
These plants are sparsely branching columnar cactus that can reach 12-20’ tall, though in cultivation in our region they usually are shorter. Branching occurs at the base of the plant, forming tight clusters. In Mexico, where this plant is native they are often planted in rows to form living fences. The cream-colored floral tubes are covered with scales that carry wool and bristles in their axils and have some reddish or pinkish coloring. The spherical fruits are more or less dry.Photo by Roberto R. Calderón on iNaturalist
Plant in full to part sun. Plants require low water, but watering them once or twice a month in summer ensures good-looking plants. No need for winter watering unless there is absolutely no rain. Container plants are watered once or twice a week in summer, seldom in winter if there is no rain. Hardy to about 25°F, the tips of the stems being the most susceptible to frost damage.
Flowers are pollinated in the day by hummingbirds, and at night by bats and moths.
Humans use this species, and other columnar cacti, as “living fences”, and so long have they been used for this purpose that the origins of species like this can be uncertain.
The Genus, Lophocereus, honors Arthur Schott, a German naturalist and plant collector who surveyed the border between the United States and Mexico. The species epithet comes from the Latin "marginatus," which means “bordered” or “lined” referring to the orderly arrangement of spines at the apex of the ribs. There are 3 species of Lophocereus in the southwestern United States and Mexico. These plants were formally placed in the genus Stenocereus.
The species is native to Central Mexico (San Luis Potosí, Querétaro, Guanajuato, Mexico D.F Hidalgo, Oaxaca). It is so widely used throughout Mexico as “living fences” that its geographic origin is uncertain.