Haseltonia

Morphological Summary

Haseltonia is a genus of giant columnar cacti from Mexico, distributed mainly in the Tehuacán-Cuicatlán Valley (Oaxaca and Puebla), designated a UNESCO World Heritage Site for its exceptional cactus diversity. Haseltonia plants are monumental succulent trees reaching 10–15 m in height. Their most distinctive feature is a lateral pseudocephalium — a zone of dense wool and bristles from which the nocturnal tubular flowers emerge. Morphologically close to Cephalocereus and Pachycereus, Haseltonia was separated as an independent genus based on floral characteristics and the lateral (not apical) position of the pseudocephalium.