Ortegocactus macdougallii

Geographic & Climate

• Geographic Coordinates: 16°21'N to 16°25'N, 95°24'W to 95°38'W (Type locality: San José Lachiguiri to San Carlos Yautepec region, Oaxaca, Mexico)

• Climate Classification: Semi-arid Tropical / Highland Savanna (Köppen: Aw / BSh transition)

• Habitat Characteristics: Endemic to restricted limestone cliffs and rocky outcrops in Oaxaca at elevations between 1,600 and 2,000 meters. Rainfall occurs predominantly during summer months, followed by a prolonged dry winter. Substrate consists of mineral-rich, highly porous calcicolous soil and weathered limestone crevices.

Botanical Morphology

• Diagnostic Features: Characterized by its unique, light yellowish-green to grey-green epidemics with a distinctive chartreuse or lime cast. Stems are small, globose to short cylindrical, divided into low, rhomboidal tubercles. Areoles bear 7–8 radial spines and 1 central spine, with prominent black-to-dark-brown tips that contrast starkly with the light epidermis. Flowers are day-blooming, bright yellow, funnelform, up to 3 cm in length and diameter.

• Growth Habit: Slow-growing perennial cactus that eventually forms low clumps or small multi-stemmed clusters up to 10–15 cm in diameter. Highly sensitive to excess moisture during its winter dormancy period.

History & Etymology

• Etymology: The genus name Ortegocactus honors the Ortega family of San José Lachiguiri, Oaxaca, who assisted in locating the species. The specific epithet macdougallii honors Thomas Baillie MacDougall (1895–1973), a natural historian and collector who discovered the plant.

• Historical Context: Discovered by Thomas MacDougall in the rugged interior mountains of Oaxaca, Mexico, in the winter of 1951–1952. Edward Johnston Alexander described it in 1961 as a monotypic genus due to its singular morphological characters spanning traits of Mammillaria and Coryphantha.