Scientific: Pachycereus marginatus (Synonyms: Lophocereus marginatus, Lemaireocereus marginatus, Marginatocereus marginatus, Stenocereus marginatus, Cereus marginatus)
Common: Mexican organ pipe cactus, Mexican fence post cactus, Central Mexico organ pipe, organo, jarritos
Family: Cactaceae
Origin: Oaxaca in central Mexico
Pronounciation: Pack-a-SER-e-us mar-gi-NA-tus
Hardiness zones
Sunset 13
USDA 9 (in urban areas only because of the urban heat island effect), 10-11
Landscape Use: Specimen or focal point in the landscape, desert landscape design themes, similar to Organ Pipe cactus (Stenocereus thurberi), but with a cleaner, sleeker, more friendly appearance.
Form & Character: Upright, stiff and visually imposing, smooth and columnar, majestic.
Growth Habit: Evergreen, succulent perennial, slow and strongly upright to 25-feet tall, mostly basally branching.
Foliage/Texture: Stems to 8-inches thick, medium glaucous to dark green, ribs 12 to 19 to 3/4-inch high, areoles white, glandular, mostly about 1/2-inch apart, spines 14 to 19, needle shaped, whitish rarely 2-inches long.
Flowers & Fruits: Nocturnal, white to purplish to 3-inches long, fruit globose, red with red flesh to 3-inches wide.
Seasonal Color: Flowers in spring and fruit in late spring to early summer.
Temperature: Tolerance similar to Organ Pipe cactus (Stenocereus thurberi). Tolerant to 28oF. In Phoenix, the urban heat island might just be enough to prevent cold damage, otherwise use in locations with good air drainage.
Light: Full sun
Soil: Requires well drained soils, especially if supplemental irrigation is being applied.
Watering: Little to none in Phoenix.
Pruning: Only occasionally remove entire stems to improve whole plant appearance and shape, otherwise none.
Propagation: Easy to propagate by stem cuttings of almost any length. After removing a stem section, allow the cut cross section to harden (callus) for about 5 to 10 days. Then direct stick the hardened stem section into the soil, right side up. Adventitious root formation will soon follow. No additional treatments are required. It's possible to propagate by seed too, but man, that will take a long time to achieve a sizable specimen.
Disease and Pests: Fungal and bacterial root rots if soil is poorly drained.
Additional comments: This is eventually a large columar cactus that is not for use in small spaces. Also, this wonderful columnar specimen is not recommended for use in highly pedestrian trafficed public areas such as the public paths along Tempe Town Lake because of vandalism wrought upon it by malicious and angry types. Propagates and transplants so easily.
A taxonomic quagmire: Yup, that's what I call it. Across the Internet, one will find this wonderful taxon placed in six different genera. Here they are with their respective botanical authorities....
I refer to this taxon as belonging to the genus Pachycereus, because this is the most commmon published description, even though the genus Lophocereus is the most recent published description. Overall, Pachycereus is a diverse genus with many species.
