Stenocereus
Stenocereus is a genus of ribbed, columnar and tree-forming cacti native to the warm, arid parts of the Americas — from the southwestern United States and Mexico through Central America to northern South America and the Caribbean. The genus includes the familiar organ pipe cactus as well as several species grown and harvested for their sweet, prized edible fruits, known collectively as pitaya or pitahaya.
Description
Members of Stenocereus are medium to large cacti with tall, strongly ribbed stems. Most branch freely from at or near the base to form a candelabra or many-armed shrub, though some develop a short trunk and grow into small trees. The stems are typically deep green to grey-green, with well-defined ribs bearing evenly spaced areoles and stout, often stiff spines that vary in length and colour between species.
Flowers are funnel-shaped and usually open at night or in the early morning, closing as the day warms; they may be white, cream, pink or reddish depending on the species, and are pollinated by bats, moths and, in some cases, hummingbirds. The fruits are fleshy, often spiny-skinned berries with juicy, seed-filled pulp in shades of red, purple, orange or white. Several species produce fruit of real commercial and cultural importance — the pitaya of Mexican markets — harvested from both wild and cultivated plants.
Distribution
Stenocereus is a New World genus centred on Mexico, which holds the greatest diversity of species. Its range extends north into Arizona (where S. thurberi, the organ pipe cactus, reaches the United States), south through Central America, and into parts of northern South America and several Caribbean islands. Plants favour hot, dry lowland scrub, thornforest and desert, generally at low to moderate elevations, growing on rocky slopes and well-drained flats.
Notable species
- Stenocereus thurberi — the organ pipe cactus, a many-stemmed species of the Sonoran Desert and the emblem of Organ Pipe Cactus National Monument in Arizona.
- Stenocereus queretaroensis — a Mexican tree cactus widely cultivated for its large, sweet pitaya fruit.
- Stenocereus gummosus — the pitaya agria or sour pitaya of the Baja California peninsula, a sprawling, sharply spined species.
- Stenocereus griseus — grown across Mexico and the Caribbean for its edible fruit.
- Stenocereus eruca — the remarkable creeping devil, whose stems lie flat and crawl across the ground, rooting as they advance while the older end dies back.
- Stenocereus pruinosus — another important pitaya species of central and southern Mexico.
Cultivation
As a group, Stenocereus are undemanding given warmth, sun and sharp drainage. Grow them in a very free-draining, mostly mineral mix in full sun; the columnar species appreciate all the light they can get and colour up and spine best when not shaded. Water generously through the warm growing season once the soil has dried, then keep plants dry and cool over winter to avoid rot. Most are frost-tender and need protection below freezing, though a few tolerate brief light frost when bone dry.
These are naturally large cacti, so give established plants room and a stout pot or open ground where the climate allows. See Watering and Repotting for general technique, and Pests and diseases for the usual troubles — mealybugs, scale and, in damp conditions, basal rot.
Propagation
Stenocereus propagate very easily from stem cuttings: a severed branch left to callus for a week or two in a dry, shaded spot will readily root when set on barely moist mineral mix. This is the quickest way to bulk up a favoured clone and is how many fruiting selections are maintained. Seed is also straightforward on a warm, humid surface but slower to reach size. See Propagation — cuttings and Propagation — seed for full walkthroughs.
Hobby and cultivar notes
In collections Stenocereus are grown both as statuesque landscape and container specimens and, increasingly, for home fruit production in suitable climates. The organ pipe is the best-known ornamental, while pitaya species such as S. queretaroensis and S. griseus are valued for fruit and are the subject of local selection for size, sweetness and colour rather than formal named cultivars. The oddities of the genus — above all the ground-crawling S. eruca — are sought after by collectors of unusual growth forms. The name Stenocereus has absorbed a number of older genera, so plants may still be met with under synonyms such as Lemaireocereus, Rathbunia, Marshallocereus and Ritterocereus.
See also
- Stenocereus thurberi · Stenocereus eruca · Stenocereus queretaroensis
- Soil and potting mix · Watering · Repotting
- Propagation — cuttings · Propagation — seed · Pests and diseases