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Family Moraceae
Castilla elastica Cerv.

Scientific names Common names
Castilla elastica Cerv.            Halimukon (Tagalog)
Accepted infraspecifics (3) Castilloa rubber (Engl.)
Castilla elastica subsp. costaricana (Liebm.) C.C.Berg Mexican rubber tree (Engl.)
Castilla costaricana Liebm.         Panama rubber tree (Engl.)
Castilla daguensis Pittier      Uletree (Engl.)
Castilla panamensis O.F.Cook       
Castilla elastica subsp. elastica  
Castilla elastica var. liga J.Poiss.          
Castilla guatemalensis Pittier       
Castilla gummifera (Bertol.) Standl.       
Castilla lactiflua O.F.Cook       
Castilla markhamiana Markham       
Castilla nicoyensis O.F.Cook         
Ficus gummifera Bertol.    
Castilla elastica subsp. gummifera (Miq.) C.C.Berg  
Ficus gummifera (Miq.) Miq.    
Urostigma gummiferum Miq.    
Castilla elastica Cerv. is an accepted species. KEW: Plants of the World Online

Other vernacular names
BRAZIL: Puluvao.
GERMANY: Castilloa, Hulebaum, Kautschukbaum.
MAYAN: Ki'c, K'ik'che'..
SAMOAN: Pulu mamoe.
SINHALA: Wal-rubber, Ron-rubber.
SPANISH: Arbol del ule, Arbor de hule, Caucho, Caucho negro, Palo de hule, Hule, Ule.

Gen info
- Castilla elastica, the Panama rubber tree, is a tree native to tropical areas of Mexico, Central America, and northern South America. (2)
- Ancient Mesoamericans were making rubber in Pre-Columbian times, ca 1600 BC, mixing latex from Castilla elastica trees with juice (25%) from Ipomea alba (morning glory) vines, and produced rubber balls (one notable use, the manufacture of balls for the Mesoamerican ballgame ollamaliztli), sandal soles, rubber bands for hafting and joining. (2) Unprocessed C. elastica latex, without I. alba juice, is best suited for joining applications, such as adhesives or hafting bands, where strength and ability to absorb shock are important.   (3)

Castilla elastica is a large tree. Bark exudate is rapid and copious. Twigs. petioles, and leaves produce a milky exudate. Leaf blades rather large, about 45 x 17 cm, petioles about 1-1.5 cm long. Stipules rather large, about 8 cm long, longitudinally veined and hairy on the outer surface. Upper surface of the leaf blades scabrous, lower surface hairy. Leaf blade margin appears to be toothed but closer inspection reveals that the 'teeth' are really tufts of hair. Lateral veins curving inside the blade margin but not forming definite loops. Flowers borne in flattened head-like clusters formed from numerous overlapping bracts. Male flowers: Flower clusters stalked, each cluster about 2-3 cm across. Stalks about 2.5-3 cm long. Female flowers: Flowers clusters almost sessile, about 2 cm across. Fruit is a flat disk of numerous green bracts with about 20-30 individual, orange-red, fleshy, 1-seeded fruits. Seeds about 8-10 x 6-8 mm. (8)

• Castilla elastica is a tree that grows up to 30 m tall with diameter up to 60 cm. It has spreading or drooping branches. Foliage: Leaves are oblong, 20-45 cm by 7-15 cm, coarse, densely hairy on both sides, base heart-shaped, tip pointed. Flowers: It is androdioecious: there are some trees which bear only male inflorescences, while others are cosexuals whereby they produce both male and female inflorescences. Stamens on both types of trees are fertile. Female inflorescences: discoidal with shallow central depression, pistils are aggregated; sessile. Male inflorescences on cosexual plants: urceolate, "fig-like" with an apical hole covered by imbricate bracts; anthers 1.6 mm in length; about 50 flowers. Staminate inflorescences on male plants: bivalvate; about 400 flowers; anther 1.2 mm in length. Fruit: Fruit is a flat disk of many green bracts with 20-30 fruits, orange-red, fleshy, each fruit bears 1 seed. (10)

- Introduced to the Philippines.
- Cultivated, not natuuralized.
- Native to
Belize, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico Southeast, Mexico Southwest, Nicaragua, Panamá. (1)
- Established in undisturbed rainforest at low elevations, posing a threat to intact native forests. In some parts of the world it is regarded as an environmental weed, notably in the Pacific, and has been included in the Global Invasive Species Database (GISD, 2008). (8)

- Studies have suggested cardiotoxicity, antivenom properties.

Parts used
Leaves, latex.


- Small, orange, fleshy fruits are edible.
- Some consider the fruit barely edible.
- In Bohol, Philippines, Eskaya healers use decoction of leaves for bathing in early pregnancy (Panagang sa lisang; Panglihi) (4)
- In Brazil, used for treatment of leishmaniasis.
- Wood: A low quality timber used for light construction.

Cardiac toxicity:
Study reports on a patient with panama rubber (Castilla elastica) poisoning who presented with severe cardiac toxicity and nodal bradycardia. The patient admitted to taking a herbal medication of juice from the leaves of the plant, which was misidentified as thebu (Costus speciosus), a food and herbal medication of the villagers. Patient was treated with intravenous atropine and oral salbutamol, and intravenous fluids. (William Withering wrote of the toxicity of herbal cardiac glycosides in 1785, in his classic work on foxglove, Digitalis purpurea. Castilla elastica is a member of the Moraceae family, some species of which have cardiac glycosides. Cardiac glycosides affect the cardiovascular, neurologic, and gastrointestinal systems. Dysrhythmia characterized by increased automaticity and depressed conduction is suggestive of cardiac glycoside toxicity. Associated arrhythmias includes bradydysrhythmias, sinus bradycardia with AV nodal block, junctional rhythms, and sinus arrest. Symptoms include palpitations, shortness of breath, chest pain, lightheadedness, dizziness, and faintness. Hyperkalemia is a life-threatening complication. (5)

Neutralization of Hemorrhagic Effect of Bothrops atrox Venom:
Thirty-one of 75 extracts used by Columbian traditional healers for snakebites showed moderate or high neutralizing ability against the hemorrhagic effect of Bothrops atrox venom. Castilla elastica was one of 19 species that showed moderate neutralization (21-72%) at doses up to 4 mg/mouse. (6)


February 2024

                                                 PHOTOS / ILLUSTRATIONS
IMAGE SOURCE: Castilla elastica leaves / Viinayaraj / CC BY SA 3.0 Unported / Image modified / Click on image or link to go to source page / Wikipedia
OTHER IMAGE SOURCE: Castilla elastica - fruit of the Panama rubber tree / Dick Culbert / Creative Commons Attribution 2.0 / Image modified / Click on image or link to go to source page / Wikimedia Commons
OTHER IMAGE SOURCE: Castilla elastica seeds / © Steve Hurst @ USDA-NRCS PLANTS Database / USDA
OTHER IMAGE SOURCE: Rubber tree / © Yotrak / Getty Images / Non-commercial use / Image modified / Click on image or link to go to source page / Geojit Insights

Additional Sources and Suggested Readings
Castilla elastica Cerv. / KEW: Plants of the World Online
Castilla elastica / Wikipedia

America’s First Polymer Scientists: Rubber Processing, Use and Transport in Mesoamerica
/ Michael J Tarkanian, Dorothy Hosler / Latin American Antiquity, 2011; 22(4): pp 469-486 /
DOI: 10.7183/1045-6635-22.4.469
Ethnomedicinal Survey of Valuable Plants Used by Eskaya Traditional Healers in Bohol Island, Philippines
/ Remedios Immarie M Teves, MD, Ourlad Alzeus G Tantengco BSc, Reina Juno U Sumatra MD, Harold M Carag MSc, Josefina S Isidro-Lapeña MD, MFM / Acta Medica Philippina
Cardiac toxicity with nodal bradycardia due to Panama rubber (Castilla elastica: Moraceae) poisoning /
EWRA Witharana, WMGASTB Wijetunga, PP Sathanandan, SKJ Wijesinghe, LGBY Wickramaratne / Ceylon Medical Journal, 2014; 59: pp 97-98
Snakebites and ethnobotany in the northwest region of Colombia: Part III: Neutralization of the haemorrhagic effect of Bothrops atrox venom /  R Otero, V Nuñez, J Barona, R Fonnegra, S L Jimenez, R G Osorio, M Saldarriaga, A Diaz /  Journal of Ethnopharmacology, 2000; 73(1-2): pp 233-241 /
DOI: 10.1016/S0378-8741(00)00321-4
The Potential of Traditional Knowledge to Develop Effective Medicines for the Treatment of Leishmaniasis / Luiz Felipe D Passero, Erika dos Santos Brunelli, Thamara Sauini et al / Frontiers in Pharmacology, 2021; Volume 12 / DOI: 10.3389/fphar.2021.690432
Castilla elastica (Panama rubber tree) / BioNET-EAFRINET
Castilla elastica (Mexican rubber tree) / CABI Compendium
Castilla elastica / National Parks: FLORA &FAUNA WEB

DOI: It is not uncommon for links on studies/sources to change. Copying and pasting the information on the search window or using the DOI (if available) will often redirect to the new link page. (Citing and Using a (DOI) Digital Object Identifier)

                                                            List of Understudied Philippine Medicinal Plants
                                          New plant names needed
The compilation now numbers over 1,300 medicinal plants. While I believe there are hundreds more that can be added to the collection, they are becoming more difficult to find. If you have a plant to suggest for inclusion, native or introduced, please email the info: scientific name (most helpful), local plant name (if known), any known folkloric medicinal use, and, if possible, a photo. Your help will be greatly appreciated.

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