Arthrocereus is a small genus of cacti in the family Cactaceae, order Caryophyllales, endemic to Brazil. The genus comprises four accepted species confined to southeast and west-central Brazil, where they grow in rocky montane habitats.
Plants are relatively small, bushy, and either erect or prostrate, with stems that are branched or unbranched. The shoots are articulated and cylindrical, bearing 10 to 18 low, narrow ribs studded with small areoles from which numerous thin spines emerge. The genus is notable for its nocturnal blooms: elongated, bell-shaped flowers open wide near the shoot tips after dark, with the flower cup and tube densely covered in wool, hair-like spines, and a few pointed scales — an adaptation associated with pollination by hawkmoths.
The fruits are spherical to obversely pear-shaped, green-skinned with white flesh, thin-walled, and do not split open at maturity. They bear scales and hair-like spines on their surface. Seeds are obliquely egg-shaped and black.
Distribution
Arthrocereus is endemic to Brazil, with species distributed across southeast and west-central regions of the country. The genus has a restricted range and is associated with rocky outcrops and mountainous terrain within the Brazilian interior.
Taxonomy Notes
Arthrocereus belongs to the family Cactaceae, order Caryophyllales. GBIF recognises 4 accepted taxa within the genus. The name Arthrocereus reflects the articulated (jointed) structure of the stems — from Greek arthron (joint) and cereus (wax candle), the latter being a long-established name applied to columnar cacti.
