Pfeiffera monacantha

Native range and recognised subspecies

Pfeiffera monacantha is native from Bolivia into north-western Argentina. It occurs in seasonally dry tropical landscapes, including Yungas and seasonal forest, where plants grow on trees and across rock faces and cliffs from roughly 300 to 2,000 m.

Botanists recognise two subspecies: subsp. monacantha and subsp. kimnachii. This plant is sold simply as Pfeiffera monacantha; variation in spines, segment shape and flower colour cannot identify the subspecies by itself.

Across its range, the species is currently considered at low risk of extinction, although conditions can differ between local populations.

Care for waxy-leaved epiphytes

Light and stem form: Bright filtered light or gentle morning and evening sun supports the change from younger angled shoots to older flattened, arching segments. Shield the plant from intense midday heat behind glass. Too little light produces weak extension and reduces flowering.

Root mix: Use an airy forest-cactus mix with bark or coarse organic matter plus mineral drainage. The mix should retain some moisture around the roots without becoming dense. Humid air can limit excessive shrivelling when paired with good circulation.

Watering, root care and temperature: In warm growing conditions, water after the upper part of the mix has partly dried and drain the pot fully. During the cooler, darker rest, water less often without leaving the thin stems severely desiccated. A cold, saturated central root zone is especially damaging.

Feeding: Feed sparingly with a balanced liquid fertiliser while new segments are developing, then withhold it during the resting period.

Recognising problems in a hanging cactus

• Angled young shoots and flatter old ones: Younger stems can be angled before later growth becomes flatter and more arching. A gradual firm transition is normal; collapse, translucency or softness at a joint is not.
• Areolar wool and small spines: Repeated tufts and short spines at the regularly spaced growth points, called areoles, belong to the cactus. Irregular cotton or attached shields that spread around joints and roots indicate mealybugs or scale.
• Flexible wrinkled segments: Thin segments that become flexible and furrowed while the pot is light and dry need water. Similar wilt while the pot remains wet points to root failure, so examine the centre and roots before increasing water.
• Dark soft bases: Cold, saturated roots or buried joints can initiate rot. Move the trailing cactus away from other plants and withhold water while checking how far the softness extends. If removal is necessary, cut back to firm tissue, let the wound callus and re-establish the segment shallowly in an airy mix.
• Hard corking at old joints: Localised dry, firm corking can form where older segments meet. Mark the edge and watch for change. If black softness or a wet margin spreads, keep the plant apart and have the problem identified before removing the segment.
• Pale or weak new growth: Bleached exposed faces indicate excessive sun, while long weak extension indicates too little light. Match the pattern to its position, then change exposure gradually so later segments form normally.
• Bronzing or sticky deposits: Mites can bronze young growth; scale or mealybugs may produce bumps, cotton or honeydew. Keep the plant apart and inspect the growth points and roots closely. Treat the pest found, making sure treatment reaches affected joints. Treat the roots only with a product intended for root use.

Keep Pfeiffera monacantha away from children and pets

• Keep this plant away from children, cats and dogs.
• Its effects after chewing or swallowing are unclear, and plant material can still cause an upset stomach.
• Contact a veterinarian or medical professional if symptoms develop or do not settle.

What does the name Pfeiffera monacantha mean?

Pfeiffera commemorates Ludwig Karl Georg Pfeiffer. Monacantha combines Greek monos, single, with akantha, spine or thorn, referring to the commonly solitary prominent spine.

Joseph Franz Maria Anton Hubert Ignatz Fürst zu Salm-Reifferscheid-Dyck established the genus Pfeiffera in 1845 in Cacteae in Horto Dyckensi Cultae, 1844, page 40.

August Heinrich Rudolf Grisebach first described it as Rhipsalis monacantha in 1879 in Abhandlungen der Königlichen Gesellschaft der Wissenschaften zu Göttingen, volume 24, page 140. Paul V. Heath later placed it in Pfeiffera as Pfeiffera monacantha in 1994 in Calyx, volume 4, page 158.