Light
Filtered Sun
Bright filtered light or partial shade; avoid harsh midday sun.
Reference image 
Reference image Epiphyllum laui
Lau's Orchid Cactus
Overview
Epiphyllum laui is an epiphytic cactus species belonging to the Cactaceae family, highly valued for its elegant funnel-shaped flowers and trailing growth habit 1. Unlike many strictly nocturnal night-blooming cereus species, this plant features diurnal elements, remaining open during the daytime.
Taxonomy and Naming
Named in honor of the renowned German botanist and cactus collector Alfred Bernhard Lau, who discovered it in Mexico, the species was formally described as Epiphyllum laui by Myron Kimnach in 1989 2. It is commonly referred to as an orchid cactus due to its epiphytic nature.
Distribution and Habitat
This species is endemic to southern Mexico, particularly in the states of Chiapas, Veracruz, and Tabasco 2. It grows in seasonally dry tropical forests as an epiphyte on tree branches or as a lithophyte in rocky crevices, where it thrives in warm, humid microclimates 3.
Appearance
The stems are flattened, leaf-like, bright green, and virtually spineless with wavy margins. The diurnal flowers are approximately 10-15 cm in diameter, featuring outer tepals in shades of yellow-orange and pure white inner tepals, producing a pleasant fragrance.
Cultivation
Epiphyllum laui thrives in bright, filtered sunlight. Unlike desert cacti, it prefers an organic-rich, highly porous, and slightly acidic medium. It requires constant humidity and protection from temperatures below 10°C.
Common Cultivation Errors
Exposing the plant to harsh, direct sunlight causes severe stem scorching and discoloration. Conversely, overwatering or poor drainage will rapidly lead to root rot and stem decline 3.
Bibliography
References
Watering
6-14 Days
Keep soil moderately moist during growth; reduce watering in winter.
Soil
Airy, acidic peat-based organic mix with perlite
Rich, acidic, well-draining epiphytic mix with perlite and bark.
Safety
Pet Friendly
Non-toxic to pets and spineless, making it very safe for households.
Difficulty
Moderate
Moderate; requires more humidity and precise watering than desert cacti.
Native Habitat
Mexico (Chiapas, Veracruz, Tabasco, Yucatan)
Native to the tropical forests of southern Mexico, where it grows nestled in tree branches under canopy shade in a seasonally dry tropical climate.
Frequently Asked Questions
Is Epiphyllum laui toxic to pets?
No, *Epiphyllum laui* is completely non-toxic and safe for cats and dogs.
How often should I water this plant?
Water roughly every 6 days in summer when the topsoil dries out, and reduce it to every 14 days in winter during its rest period.
What kind of potting soil should be used?
A well-draining, airy, organic-rich, and slightly acidic mix (peat, orchid bark, and perlite) is ideal for this epiphytic cactus.
Can Epiphyllum laui take direct sunlight?
It should be protected from harsh, direct midday sun. Bright, filtered indirect light is best for growth and blooming.
How can I encourage blooming?
Provide a cool (10-15°C) and dry winter rest period for a few weeks to stimulate abundant bud formation in spring.
When does it bloom and are the flowers fragrant?
It blooms in late spring to early summer. The flowers open during the day and possess a very pleasant, sweet fragrance.
What causes yellowing and softening of the stems?
This is typically a symptom of root rot caused by overwatering or poor soil drainage.
What is its growth rate?
With adequate humidity and warmth, it exhibits a moderate to fast growth rate, producing cascading, trailing stems.
What should the indoor humidity level be?
It prefers a minimum humidity of 55%. Misting the stems during dry spells or using a humidifier is highly beneficial.
How is it propagated?
It is easily propagated by taking stem cuttings in spring or summer, letting them callus for a few days, and planting them in moist soil.