Mexipedium xerophyticum is a rare and unique slipper orchid species from Mexico. It has small white flowers with pink staminodes. They bloom sequentially, usually appearing one at a time on the inflorescence.
Each spike can stay in bloom for many months. This species blooms for us from early summer through fall. New growths are produced on stolons (runners), which can rapidly fill a pot when the plant is well grown.
Mexipedium xerophyticum was originally described as Phragmipedium xerophyticum in 1990. It was separated to its own genus after DNA analysis (Albert and Chase, 1992). Since taxonomists dislike monotypic genera, we often see it referred to as a Phrag. However, it is quite clear that this is a unique genus.
When this species was discovered there were only seven individual plants found in the habitat. The location is a single limestone outcrop in Oaxaca, Mexico. An expedition in 2009 determined that a fire had destroyed all but one of the original plants, but six more specimens were found nearby (Perez Garcia, 2011).
This species is a lithophyte (it grows on rocks). It is found on vertical rock walls with northern exposure (Perez Garcia, 2011). Its growth habit has been described as similar to many Paphiopedilum in the Parvisepalum section such as Paphiopedilum micranthum. The region has a very wet summer season and a distinct dry season from winter into spring. You can find more details here http://www.orchidspecies.com/mexxerophyticum.htm
According to Perez Garcia (2011), Mexipedium is considered a species in Danger of Extinction on the Official Mexican Regulations for species at risk. No small seedlings have been observed in situ, only mature plants. The range where they have been seen is about 1 hectare and the area is prone to fires. This is clearly a species with a very unstable wild population.
It is my opinion that this species was already in the process of going extinct in nature when it was discovered. The habitat is so small and fragile and there are so few plants. The limestone outcrops will, over time erode and the habitat will be lost. Whether it would take decades, centuries or millennia its extinction seems inevitable.
Fortunately, Mexipedium has been reproduced artificially for many years now. However, I am not aware of any efforts to reintroduce plants to the wild.
How do I grow it?
This is a very easy species to grow. As always, we need to consider how it grows in situ. Since it is a lithophyte, we know it will not tolerate ‘wet feet’. We use our standard well-drained potting mix consisting of Orchiata pine bark with about 30 % #3 perlite and 30% charcoal.
Ideally water should be high quality with low soluble solids. We recommend RO water or rainwater for optimum growth. We fertilize every week with a complete fertilizer such as the MSU formula. In the summer months we increase the rates to 350 ppm Nitrogen, and back off to 100 ppm during the shortest winter days. It is important to flush the pots thoroughly on a regular basis in order to prevent salt build up.
We repot these every year as they appreciate fresh media. As this species spreads by stolons, a wider, flatter pot is preferred once they get larger. This makes it easier to redirect stolons in order to keep them in the pot. If they do not come into contact with the potting mix the new growths will not produce roots.
Other interesting notes
Victor Albert has successfully sequenced the genome of this species. His work is not yet published.
Where can I get one?
Our goal is to always have seedlings of this species available. There is a good supply in the pipeline at all stages of development. You can find them here https://paphparadise.com/product/mexipedium-xerophyticum-2/
We occasionally have divisions of our stud plants available. Drop us a line if you are interested.
Albert, V. A.; Chase, M. W. (1992). “Mexipedium: A New Genus of Slipper Orchid” (Cypripedioideae: Orchidaceae)
Pérez García, Eduardo A. (2011). “The Rediscovery of Mexipedium xerophyticum” Slipper Orchid Alliance Newsletter Vol. 12 (1):10-13. https://www.facebook.com/notes/asociacion-mexicana-de-orquideologia/the-rediscovery-of-mexipedium-xerophyticum/749835665044123/