Pachypodium ambongense
Plant Family
Apocynaceae (dogbane family)
Binomial Name
Pachypodium ambongense Poiss.
Synonymous Binomial Names
None.
Common (Vernacular) Names
Lost Pachypodium, elephant’s trunk. Madagascar: songosongo or betano.
Plant Characteristics
Endemicity. Endemic to Madagascar, it has a very localized habitat in the area of the river Ambonho (Ambongo) on the tsingy at Namoroka Reserve about 200 km north of Bemaraha in the Province of Mahajanga. It is known only from 2-5 localities. It grows in open deciduous, hot, dry forests in crevices filled with black humus on inselberg and limestone rock faces (Anonymous 2018).
Growth Habit. A shrub reaching a maximum height of about 2m (6 feet). Some specimens in cultivation have a single branchless trunk while others may have multiple branches, usually extending from the top of the trunk. The trunk and branches have hard, sharp thorns with a snakeskin-like bark. The leaves of plants in cultivation may be lost or partially lost during the winter months.
 Pachypodium ambongense, Single Stem |
 Pachypodium ambongense, Multiple Stems |
 Pachypodium ambongense, Snakeskin-Like Thorny Trunk |
Crestate Form. One of the seedlings from the last batch of seed that we planted here in Hawaiʻi was crestate. This is apparently the first and only crestate form of this rare species ever reported. We shipped it to a specialist nursery in Arizona for production of additional plants from cuttings. Unfortunately it died shortly after shipment from unknown causes.
 Pachypodium ambongense, Crestate Form |
Flower Buds are striped like candy canes.
 Typical Flower Bud of Pachypodium ambongense |
Flowers. The inflorescence is sessile with a petiolate stalk. The flowers are white with yellow centers and five-merous. They closely resemble those of the common periwinkle (Cataranthus roseus), a related species also endemic to Madagascar.
 Pachypodium ambongense, Flower |
Seed Pods. After pollination the flowers fall off, their stalks thicken and then the tiny seed pods begin to emerge at their tips. At this stage they are highly susceptible to fungal infections, apparently initiated from spores transmitted by water from raindrops entering the tips. These infections have been confined to the pods and their stalks.
 Early Pod Formation on Pachypodium ambongense |
The pods consist of two “horns” that turn brownish and dehis when mature releasing the seeds, which are carried by the wind. The pods in the photo below formed on a California customer’s plant that was pollinated before shipment from Hawai`i!
 Maturing Seed Horns on Pachypodium ambongense |
Seeds. The seeds shown in the photo were separated from their pappi.
 Pachypodium ambongense Seeds |
 Emerging Seedling of Pachypodium ambongense |
Conservation Status
This species is in danger of extinction. The habitats of the pachypodia in Madagascar are disappearing fast due to human impacts. Urbanization and agriculture cause the decline of habitats and distribution range of many species, putting the smaller, slow-growing ones especially at risk (SANBI 2018).
CITES Listing: Pachypodium ambongense is listed on CITES Appendix I (Most endangered). All commercial international trade is prohibited (CITES 2018).
IUCN Listing: This taxon has not yet been assessed for the IUCN Red List of Threatened Species™ (IUCN 2018).
U.S. Endangered Species Act Listing Status: Taxon not listed (FWS 2018).
Uses
Ornamental and Landscaping Uses. This species is drought and heat tolerant, suitable for use in as a specimen plant and in xeriscaping. It may also be grown indoors as a bonsai subject.
Traditional Medicinal Uses. An extensive literature search revealed no reported traditional medicinal uses of this plant.
Purposes of Our Research. A primary objective of our research is to test methods of propagating this plant in artificial cultivation to increase supplies for other research purposes and ex situ conservation by where it can be protected from the factors contributing to its decline in the areas where it is endemic. Some authors argue that the mastering of propagation and cultivation would be the only means to ensure the long-term survival of many of these Pachypodium species (SANBI 2018).
We also believe that plant materials derived from this species may contain compounds with potentially important pharmacologic applications. Compounds found in the closely related Madagascar Palm, (Pachypodium lamerei) have shown anti-bacterial and anti-fungal activity against human pathogens (El-Kashef et al. 2015). Vinblastine and vincristine, wonder drugs for treatment of cancer, are produced from the leaves of related Madagascan species Catharanthus roseus, commonly known as the Madagascar periwinkle, rose periwinkle, or vinca, in a symbiotic relationship with Fusarium oxysporum, an endophytic fungus (Kumar et al. 2013).
Production of additional plants in artificial cultivation is necessary to carry out further pharmacologic investigations.
Educational Displays. The rarity and unusual appearance of this species as specimen plants makes it an interesting subject for educational displays intended to improve awareness of the importance of protecting endangered species that could be sources of important drug discoveries. Display specimens we provided of Catharanthus roseus and Pachypodium ambongense have been used repeatedly for this purpose. The message conveyed is that Catharanthus is the source of important drugs for cancer treatment; P. ambongense could also contain import undiscovered drugs but it is in danger of extinction. These displays have been presented at several major events including White House GreenGov Symposia and Earth Day celebrations at the National Institutes of Health (NIH) and the National Cancer Institute:
At NIH’s combined observances of Earth Day and Take Your Child to Work Day, NCI-Frederick’s Dr. David Newman, chief of the Natural Products Branch, explained how protecting endangered species helps us find new plant compounds and new drugs (Waring 2007). He is pointing to our Pachypodium ambongense specimen.
 Plant Display at NIH Earth Day 2007 |
A display of endangered medicinal plants comparing Catharanthus roseus and Pachypodium ambongense at a White House environmental symposium.
 Endangered Medicinal Plant Exhibit |
Cultivation
While this plant is very rare it is easy to grow. It may be grown outdoors in tropical climates or indoors as a container plant.
This was probably the last of the Pachypodium species to be introduced in cultivation. Very few specimens of this plant, described by some as “ultra rare” have been available until recently and CITES now prohibits all international trade for commercial purposes. Plants grown from limited domestic seed sources are slowly becoming more available to collectors.
In 2004 the Huntington Botanical Gardens (HBC) offered seedlings of the plant as one of their International Succulent Introductions (Trager 2004). We grew the specimen in the photo below from one of the HBC seedlings and it was the same plant used for several years the educational displays. Eventually it reached a height of about six feet and could no longer be maintained in our small greenhouse. We donated the plant and shipped it from our facility in Frederick, Maryland back to HBC in Pasadena, California. The main plant subsequently died shortly after its arrival in California from rot that probably began in the prior winter months in Maryland. Back-up cuttings taken from the main plant before shipment survived and were returned to the HBC.
 Pachypodium ambongense Mature Specimen 2m Tall |
Cultivation in Hawaiʻi. We were the first growers of this species in Hawaiʻi. It thrives in our area of Hawai`i Island that was previously dry forest with a climate similar to areas where the plant is endemic. Our volcanic soils tend to be acidic so soil amendments of limestone or similar alkaline materials like coral rock are recommended to better match the soil conditions from where this species is endemic. The plants were unaffected by ash and high levels of vog from recent volcanic eruptions upwind of our location.
Propagation
Seeds. This plant is easily propagated from fresh seeds. We have observed that the form, size, pest and disease resistance, and dormancy patterns of plants grown from the same seed lot can be highly variable.
Cuttings: We have successfully grown this plant from cuttings but there tends to be high losses from rot. They may be rooted in water and then transferred to planting media. Offsets taken from the bases of plants under the soil line often have roots. These can be cut from the main plant. After allowing the cutting wounds to dry for several days these offsets typically survive and grow into vigorous plants.
Planting media: Commercial mixes used for cacti are suitable with amendments of limestone, dolomite or coral rock (10-20% by volume) are recommended.
Improved Cultivars
Improved cultivars of this species have not been developed.
Pests and Diseases
We have not observed significant problems with pests or diseases in growing this plant indoors in a greenhouse. Plants grown in cool conditions and wet, poorly drained soil are subject to rot.
Fungal diseases. Some plants get mildew on their leaves when grown outdoors, while others are resistant. Of the fungicides we tested sulfur emulsions appear to provide the best treatment but provide incomplete control. Weekly treatments may be required. New seed pods of plants grown outdoors are highly susceptible to a black fungus that may be anthracnose transmitted by rain. The fungus prevents pod maturation and eventually kills them but does not spread to other parts of the plants.
Pests. Some plants are highly susceptible to white peach scale (Pseudaulacaspis pentagona), other scale insects and occasionally mealybugs. Other plants may be completely resistant. There are many host species of the white peach scale in our area such as papaya that provide ongoing sources for re-infestation. This pest is difficult to control. Small scale infestations may be treated by spraying with alcohol and removal with a toothbrush. Few pesticides list this pest and most that we have tried are ineffective. The best results have been with dinotefuran based systemic insecticides such as Safari®, which provides long term control. A parasitic wasp has been introduced in other areas of Hawai`i Island and is reportedly an effective biological control.
We have found that mealybugs can be removed by high pressure water sprays and controlled by applications of horticultural oil or neem oil. These are not 100% effective and may have to be used frequently.
Invasiveness Potential
Hawai‘i-Pacific Weed Risk Assessment (HPWRA) Program. We requested the program to assess the invasiveness potential of this plant since we could find no indications of prior introductions in Hawaiʻi. HPWRA completed the assessment and assigned it an assessment score of 0.0, indicating low risk (HPWRA 2017). It has been designated as a Pono Plant, a good choice for planting in Hawaiʻi.
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Global Invasive Species Database. This species was not found on the database (GISD 2018).
Toxicity and Handling Precautions
All Pachypodium species should be considered potentially toxic by ingestion. They contain steroidal toxins referred to as cardiac glycosides that may have potent digitalis-like effects. Assays of Na+/K+-ATPase inhibition are used to measure toxicity. Assay results from a recent study suggest that Pachypodium ambongense is toxic but at a lower level than several other species such as P. rutenbergainum (Agrawal et al. 2018).
Most Pachypodium species have sharp thorns and should be handled with precautions to avoid injury. Puncture wounds from these plants can be painful and slow to heal. The thorns on Pachypodium ambongense are sharp but thicker than some other species such as P. geayi and P. nomaquanum and may be less likely to break off in wounds.
Plants and Seeds for Sale
Availability
Seeds of this species are rarely available. Plants and Certified Nursery Stock (CNP) of this species grown from seeds were sold out for about five years. From past experience our inventories sell out quickly. If you are interested in purchasing these please contact us so that we can notify you when they are offered for sale.
Seeds. Seeds of this species are not currently offered for sale. Very limited quantities of seed may be available in 2025.
Live Plants – Nursery Stock. We have propagated several plants from cuttings and offsets. These went on sale on November 5, 2024. Seed grown plants may be available by mid-2025.
Shipping Information
As certified nursery stock these plants can be shipped to all states except California. This species is listed on CITES Appendix 1 and cannot be shipped outside the U.S. If there is interest we may be able to obtain a permit modification allowing exports. This may be a prolonged process. Please contact us if you are interested.
Because of the fragility, shape, large size and weight of some of these specimens they may be difficult and costly to prepare and ship. Please contact us before ordering these to discuss shipping arrangements.
2024 Year End Update
Our large inventory of this species in Hawai`i came from one lot of seeds planted here in 2016. Most of the seedlings survived, grew quickly, reached maturity and began to bloom about three years later. With artificial pollination many of the blooms began to form pods but they proved to be highly susceptible to an anthracnose-like fungus that could not be controlled on plants kept outdoors. We were also rapidly running out of space for these in our certified nursery areas and wanted to protect this ex-situ population of critically endangered plants by distributing them to other locations and so decided to put them up for sale. They sold out rapidly to collectors and specialists on the U.S. mainland.
Two large specimens were retained for our research here and additional attempts to produce seeds and new plants from cuttings were made. We named these two specimens “Helle” and “Uri” in honor of Helle Olsen and Uri Golman, the renowned National Geographic Explorers and photojournalists, for their ceaseless efforts to promote conservation by creating more love and understanding of our natural world. The tallest specimen is “Uri” and the bushy one is “Helle”.
 Pachypodium ambongense Named “Uri” |
 Pachypodium ambongense Named “Helle” |
Even though these specimens were planted from the same seed lot, on the same day, and have been grown under identical conditions they have taken on very different forms and growing characteristics. Uri continues to grow taller and taller and may now be one of the largest known specimens of this species. He is susceptible to mildew but has never had scale infestations. Helle has a short, bushy form, blooms profusely, is highly susceptible to scale insect infestations and never gets mildew. All of this indicates that there is significant genetic diversity within the species and this diversity can greatly affect the survival of the species in new environments.
Attempts to pollinate flowers with pollen from other flowers on the same plant have repeatedly failed. Apparently is species is self-sterile. Hand pollination of plants with pollen from other plants has produced numerous pods but these become infected with a fungus that prevents them from maturing and eventually causes the pods to turn black and fall off. The fungus appears to be transmitted by rain, as observed in the related species of Hoodia grown here. Various methods have been used in attempts to control the fungus. In early 2024 pods formed on Helle. She was moved into our greenhouse and treated with a biological fungicide. Three pods have matured, and seeds from two of them are viable and producing robust seedlings. Pods from Uri have also produced seeds, and germination testing is in progress.
References
Agrawal AA, Ali A, Johnson MD, Hastings AP, Burge D, Weber MG. 2018. Toxicity of the spiny thick-foot Pachypodium. Am. J. Bot. 105(4): 1–10. doi:10.1002/ajb2.1057
Anonymous. 2018. Pachypodium ambongense Poiss. The Encyclopedia of Succulents. http://www.llifle.com/Encyclopedia/SUCCULENTS/Family/Apocynaceae/14803/Pachypodium_ambongense [accessed 14 October 2018].
CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). Appendices I, II, and III valid from 4 October 2017. https://www.cites.org/eng/app/appendices.php [accessed 13 October 2018].
El-Kashef DF, Hamed A, Khalil HE, El-Baky RMA, Kamel MS. (2015). Phytochemical and antimicrobial studies of Pachypodium lamerei. J Med. Plant Res. 9:1123-1130. DOI: 10.5897/JMPR2015.5984.
FWS (U.S. Fish and Wildlife Service). 2018. Endangered Species Home. Search Endangered Species Database. https://www.fws.gov/endangered/ [accessed 13 October 2018].
GISD.(Global Invasive Species Database) 2018. http://www.iucngisd.org/gisd/search.php Searched on 13 October 2018.
HPWRA (Hawaii-Pacific Weed Risk Assessment). 2017. Pachypodium ambongense Poiss. http://www.plantpono.org/files/Pachypodium%20ambongense.pd [accessed 14 October 2018].
IUCN (International Union for Conservation of Nature). 2018. Version 2018-1. The IUCN Red List of Threatened Species™. http://www.iucnredlist.org/search [accessed 12 October 2018].
Kumar A, Patil D, Rajamohanan PR, Ahmad A. 2013. Isolation, purification and characterization of vinblastine and vincristine from endophytic fungus Fusarium oxysporum isolated from Catharanthus roseus. PLoS ONE, 8(9), e71805. DOI: http://doi.org/10.1371/journal.pone.0071805
Trager JN. 2004. ISI 2004-34. Pachypodium ambongense Poisson. http://www.huntington.org/botanicaldiv/isi/ISI2004/2004-34.html [accessed 16 October 2018]. Originally published in the Cactus and Succulent Journal 76(2), March-April, 2004.
Waring B. 2007. Take Your Child to Work Day Grows Greener. NIH Record. Vol. LIX(10):1. https://nihrecord.nih.gov/newsletters/2007/05_18_2007/story1.htm
Page last updated on November 4, 2024.