Rauhocereus is a monotypic genus of cacti (family Cactaceae). Its only species is Rauhocereus riosaniensis,[1] which has nocturnal flowers.[2] It is known from northern Peru (Rio Santa, Rio Zana, Chamaya and Jaén).
The mostly shrubby Rauhocereus riosaniensis, usually branching from the ground, often forms thickets up to 4 meters high. The upright, columnar shoots are bluish-green and have a diameter of . The 5 to 6 ribs are broken up into many warts. 2 to 8 strong spines, up to long, emerge from the woolly areoles. The lower ones are initially reddish, the upper ones yellowish. Later all become greyish-white.
The bell-shaped flowers appear near the shoot tip. They open at night, are long and have a diameter of up to . The flower cup and the flower tube are covered with small scales and curly brown hairs.
The red, fleshy fruits are ovoid with a persistent flower rest. They contain small, ovoid, shiny black seeds.[3]
The genus and its only species were first described in 1957 by Curt Backeberg.[1], Plants of the World Online accepted two subspecies:
Rauhocereus riosaniensis is found in northern Peru in the Amazonas and Cajamarca regions at altitudes of 500 to 1000 meters.