Blue Myrtle Cactus

Myrtillocactus geometrizans is endemic to central and southern Mexico.

• Found across a broad range including the states of Puebla, Oaxaca, Guerrero, Morelos, Hidalgo, and Jalisco
• Occurs at elevations of approximately 500 to 2,200 meters
• Grows in tropical deciduous forest, thorn scrub, and xerophytic vegetation on rocky hillsides and canyon walls
• The species is adapted to a seasonally dry tropical climate with a pronounced dry season
• First described by the French botanist Charles Lemaire in 1839 as Cereus geometrizans
• Mexico is the center of diversity for the genus Myrtillocactus, which contains approximately 4 species
• The species has been cultivated in Mexican gardens for centuries for its edible fruits

A large, branching, tree-like columnar cactus.

Stems:
• Erect, columnar, branching from the base and along the main stems to form a candelabra shape
• Individual stems 6 to 12 cm in diameter, reaching 3 to 5 meters tall in habitat
• Distinctive blue-green to glaucous blue coloration due to a waxy bloom on the epidermis
• Ribs: 5 to 8 (commonly 6), deep, sharply defined, with a geometric precision
• Areoles: small, gray-felted, spaced 1 to 2 cm apart along the ribs

Spines:
• 3 to 5 per areole, short (3 to 8 mm), grayish-white to brown, slightly curved
• Relatively harmless compared to many columnar cacti

Flowers:
• Small, funnel-shaped, 2.5 to 4 cm in diameter
• Creamy white to greenish-white, nocturnal to crepuscular (opening in late afternoon)
• Appear along the upper ribs in spring to summer
• Scented

Fruit:
• Small, globose, 1 to 2 cm in diameter
• Dark purple to nearly black when ripe, resembling blueberries
• Edible, sweet, with tiny soft seeds
• Sold in Mexican markets under the name "garambullo"

Occurs in tropical deciduous forest and thorn scrub habitats in central Mexico.

• A component of the xerophytic vegetation that thrives on rocky slopes and canyon walls
• Flowers are pollinated by bats and moths, reflecting the nocturnal to crepuscular blooming habit
• Fruits are consumed by birds, bats, and other wildlife, which disperse the seeds
• Provides perching and nesting sites for birds in its branching canopy
• The deep root system stabilizes rocky slopes and aids in erosion control
• In some regions, it forms extensive thickets alongside other columnar cacti and agaves

Light:
• Thrives in full sun to very bright light
• Full sun intensifies the blue-green coloration
• Can tolerate some light shade, particularly in extremely hot climates

Soil:
• Adaptable to a range of well-draining soils
• Standard cactus mix with added perlite or pumice works well
• Tolerates slightly alkaline soils

Water:
• Water regularly during the active growing season (spring to autumn)
• Allow soil to dry between waterings but do not let it remain parched for extended periods
• Reduce watering in winter but do not eliminate entirely
• More water-tolerant than many cacti once established

Temperature:
• Hardy to approximately -4°C for brief periods
• Best growth at 18 to 30°C
• Protect from extended freezing conditions

Propagation:
• Easy from stem cuttings; allow cut surface to callus for 1 to 2 weeks
• Also propagates readily from seed
• Seedlings grow relatively fast for a columnar cactus
• Widely used as a grafting rootstock for smaller, slower-growing cacti