Rauhocereus

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 8 to 15 cm (3.1 to 5.9 in). The 5 to 6 ribs are broken up into many warts. 2 to 8 strong spines, up to 5 cm (2.0 in) 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 8 to 10 cm (3.1 to 3.9 in) long and have a diameter of up to 5 cm (2.0 in). 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.^[5]

The genus and its only species were first described in 1957 by Curt Backeberg.^[2] As of October 2023^[update], Plants of the World Online accepted two subspecies:^[3]

• Rauhocereus riosaniensis subsp. jaenensis (Rauh) Ostolaza
• Rauhocereus riosaniensis subsp. riosaniensis

Rauhocereus riosaniensis is found in northern Peru in the Amazonas and Cajamarca regions at altitudes of 500 to 1000 meters.^{[citation needed]}

• Media related to Rauhocereus at Wikimedia Commons
• Data related to Rauhocereus at Wikispecies