202nd Meeting – September 2000


Killers & Healers: Fantastic Flora of Thailand

A talk and presentation by David Engel


Thailand’s native plant species comprise many with pharmacological properties both beneficial and detrimental. I have assembled typical examples often seen along the roadside, in wastelands, in the wild, and more commonly seen even in many gardens. Plants in Thai folk medicine are versatile, treating medical disorders as well as serving industrial purposes. When I refer facetiously to some of the plants as villains, you should understand, as in most living things, they harbor a mix of good and bad. That will become apparent as we proceed through the list. Observe closely the projected photos of their leaves and flowers.

Much of the data was gathered from the trustworthy book, Medicinal Plants of Thailand, published in two volumes by the Department of Pharmaceutical Botany, Faculty of Pharmacy, Mahidol University, Bangkok. Additional information comes from my research done at the Singapore Botanical Garden and the New York Botanical Garden. Other data come from the Internet.

I have categorized the plants by the spheres of their application in both medicine and industry, as follows: Fragrance, Eyes, Dye, Mouth, Skin, Insect bites, Fever, Fainting, Digestive tract, Urinary and, Blood systems, Respiratory system, Muscles, Bones and Joints.


This information is claimed in traditional Thai drug recipes. But the advice is general not specific to individuals. “Do not try self-diagnosis or attempt self-treatment for serious or long-term medical problems without consulting a qualified practitioner.”

The Healers


Kradang-nga SongkhlaCananga odorata fruticosa – Ylang-Ylang: The flower is an ingredient in Ya-hom. It is used with coconut or palm oil to produce Macassar Oil. Applied topically, the leaves sooth itchy skin. 

Op-ChoeiCinnamomum spp. – Cinnamon Tree: Ingredients of Ya-hom and Ya-nat. The wood, twigs, bark, root, and leaves are used to treat a variety of disorders such as joint pains, insect bites, sore throat, fever, worms, and indigestion. 

SarapheeMammea siamensis: The dried flower is an ingredient of Ya-hom. It is also used as a heart tonic.

Phi-KhuunMimusops elengiMedlar Tree, Bullet Wood. The dried flower is an ingredient of Ya-hom. The bark decoction is used for sore throats and as a mouthwash to treat gingivitis.

PhayomShorea roxburghi – The flower is an ingredient of Ya-hom. As a decoction it is used to relieve fever.

Cham-phaaMichelia champaca: The distilled essence of the flower is used in perfumes and hair oil.


MonMorus albaMulberry Tree – The leaf is used as an eyewash to treat infection and blurred vision. The leaves also feed silk worms.


Kham-saetbixa orellanaAnnatto – The seed is used as a coloring agent for food and cloth. American Indians in the tropics used it for body paint.

FaangCaesalpinia sappan – The wood produces a coloring agent for food and cloth; red dye comes from the heartwood. The seeds are used as a sedative.

Thian-khingLawsonia inermisHenna Tree: The dried powdered leaf produces hair dye (red-brown to red-orange). The fresh leaf when mixed with turmeric and salt relieves inflammation of infected nails.

Inthanin-namlagerstroemia speciosaQueen’s Crape Myrtle, Pride of India: The bark produces a yellow dye.


FaraangPsidium guajavaGuava: The fruit is used as a deodorant for bad breath and the leaf for anti-diarrheal and anti-dysentery treatment.

KhoiStreblus asperSiamese Rough Bush, Toothbrush Tree: The bark is used as a tooth powder to treat periodontal disease and toothache; it also relieves diarrhea, dysentery and fever. The seed boiled in fixed oil are applied topically to hemorrhoids. A leaf infusion is used as a laxative. 

Skin, Insect Bites:

Saniat-moraaAdhatoda vasica: The crushed leaves are used to stop bleeding.

Chong-raa (Salet-phangphon)Barleria lupulinaHop-headed Barleria: The fresh leaf crushed with small amount of alcohol is applied to an abscess and insect bites to relieve inflammation. The root ground with alcohol relieves centipede bite. 

MalakoCarica papayaPapaya: The white latex from the unripe fruit contains “Papain”, which in tablet form treats wound inflammation.

Mang-khutGarcinia mangostanaMangosteen: The dried rind contains tannin that has anti-fungal properties. It is commercialized as a cosmetic cream for acne and boils. 

BunnakMessua ferreaIron Wood: Applied topically as a poultice the leaf aids healing. The bark resin is anti-bacterial and anti-inflammatory. (In India regarded as sacred tree by Buddhists.)

Bai-rabaatArgyreia nervosaWooly Morning Glory, Elephant Creeper: Fast spreading climber, evergreen, twining root. The root is used to treat allergic dermatitis. The leaf crushed with water is applied to heal abscesses and wounds. Fresh leaf juice is used as ear drops to relieve inflammation in ear.

Fai-duean-haaAsclepias curassivicaBlood Flower, Curacao Milkweed: The leaf is applied topically to relieve abscess inflammation. 

Nom-sawanClerodendron paniculatumPagoda Flower, Quezonia: The flower is used to treat inflammation from animal and insect bites. The stem is especially used to treat centipede and scorpion bites.

Maduea uthumphonficus racemosaCluster Fig Tree: The bark is used for wounds in a wet dressing, it reduces bleeding.

PhuttanHibiscus mutabilisCotton Rose, Confederation Rose, Changeable Rose: Leaves and flowers are antibacterial; they are used in the form of a poultice as a treatment for boils. The roots are boiled or ground with water and apply topically for skin allergies and to alleviate itching. 

Yaang-naa, Yaang-yuak, Yaang-maenam, Thon-yaangDipterocarpus alatus – The resin (wood oil) is used as an antiseptic for cuts and wounds.

MamuangMangifera indicaMango: The flower is used as a mosquito repellent and the seeds, in powder form, are used to treat scorpion sting.

Fever, Fainting:

MafueangAverrhoa carambolaCaramba, Country Gooseberry: The leaf and root are used to relieve fever and the ripe fruit is a diuretic.

Sadao-baanAzadirachta indica siamensisSiamese Neem Tree: The petiole and root are antipyretic and anti-emetic, the bark is used to treat diarrhea and dysentery, the fruit is used to treat urinary problems, and when ground up and macerated with water the fresh leaf and seeds are an insecticide. 

KhuunCassia fistulaGolden Rain Tree, Golden Shower, Indian Laburnum: The flower is used as an antipyretic, and a laxative. The pulp around the seed is an expectorant, and a natural laxative. Young leaves are eaten raw. 

Prathat-yaiQuassia amaraBitter Wood, Surinam Quassia: The root is used as an antipyretic. 

Ma-yomPhyllanthus acidusOtaheite Gooseberry: The root is used as an antipyretic, and the leaf boiled in water is used to bathe affected parts to relieve itching.

SakTectona grandisTeak: The wood, used in plaster form, treats fever, swellings and edema. It is also a diuretic. The bark is used to treat diarrhea.

Digestive tract:

Phayaa-sathabanAlstonia scholarisDevil Tree, White Cheesewood, Blackboard Tree. Despite its poisonous sap, the stem bark produces anti-dysenteric properties as well as an astringent remedy for colds and bronchitis. An extract from the bark reduces blood sugar in animals; and it is anti-bacterial in vitro.

Saai-nam-phuengLonicera japonicaHoneysuckle. Fresh stem decoction treats diarrhea and dysentery, it is also used as a diuretic.

MakhamTamarindus indicaTamarind. The pulp is used as a laxative and the seed kernel is used as an anthelmintic to expel parasitic worms, (helminthes), from the body.

Thap-thimPunica granatumPomegranate. The dried fruit rind is ground up in a small amount of water and applied externally to treat fungal diseases on the feet.   

AraangPeltophorum dasyrachis – The stem bark decoction is used to treat diarrhea, as a carminative to combat flatulence and as an anti-dysenteric.

Chum-het-thetCassia alataRingworm Bush. The dried leaf and fresh flower are used as a laxative and the fresh leaf ground up with alcohol is used to treat ringworm.

Lep-mue-nangQuisqualis indicaRangoon Creeper. The kernel from the dried ripe seed is used as an anthelmintic and to treat roundworm.

Kanpa-phruekCassia bakerianaPink Shower Tree. The seed aril is used as a mild laxative for children.

NoraaHiptage benghalensis – The wood is used as a carminative to combat flatulence. 

NgiuBombax ceibaKapok Tree, Red Silk Cotton Tree. Gum from the bark and roots is used to treat diarrhea, dysentery and as an emetic to induce vomiting.

Urinary, Blood Systems:

Krabue-chet-tua, Lin-krabueExoecaria cochinchinense – The fresh leaf is used to dispel stagnant blood after birth labor.

Krachiap-daengHibiscus sabdariffaRoselle. An infusion of the seed and dried calyx is used as a diuretic, and an infusion of the leaf and twig as cough medicine.

Sai-yoi-bai-laemFicus benjaminaWeeping Fig, Golden Fig, Tropical Laurel, Small-leafed rubber plant. The aerial roots are used as a diuretic and the latex for liver treatment.

Naang-yaemVolkameria fragransBurma Cone-head, Lady Nugent’s Rose. The root is used as a diuretic.

Respiratory System:

ManaaoCitrus aurantifoliaLime. Fresh lime juice is used as an expectorant, cough medicine, and to combat scurvy.

BeepMillingtonia hortensisIndian Cork Tree. The dried flowers are smoked to treat asthma and relieve coughs. The roots are used to treat tuberculosis.

Waan-kaap-hoi-yaiRhoeo spathacea, (Tradescantia spathacea) – Oyster Plant, Purple-leafed Spiderwort, Moses in a Boat. The fresh leaf is used to relieve a sore throat, a cough and thirst. They are also used topically as an anti-inflammatory.

Khon-sawanIpomoea quamoclitCypress Vine, Star Glory, Cardinal climber. The stem and leaf decoction is used to treat a bloody cough.

Muscles, Bones, Joints:

Phlap-phlueng-dok-daengRed Crinum, Spider Lily. The heated fresh leaf is applied topically to sprains and swellings. 

BEWARE: Here are some potential Killers

The Apocynaceae family comprises, worldwide, around 1,700 species, ten genera, and in Northern Thailand alone, 17 species. They are grown for their showy flowers, but almost all, disturbingly, produce a poisonous white latex.

Yee-thoNerium indicaOleander. All parts of the plant are extremely poisonous. The latex sap may inflame the skin and eyes. Smoke from burning leaves is irritating. Even eating three leaves could prove fatal, and people have died from eating meat cooked on oleander skewers; so perished, it is believed, some of the soldiers of Alexander the Great.

Baan-bureeAllamanda catharticaGolden Trumpet. It can be either a bushy or a climbing shrub with bright yellow, faintly fragrant, campanulate flowers that bloom profusely along the fence in many a Thai front yard. As with all members of the Apocynaceae family, it possesses a poisonous milky sap, but its leaves are used in a decoction as a purgative. Also, they are boiled to produce a vapour inhaled to treat coughs.  

Ram-phoeiThevetia peruvianaTrumpet Flower, Lucky Bean, Be-still Tree. The most insidiously toxic of all. A large shrub or small multi-stemmed tree, native of tropical America but commonly present in Thailand. Look closely at the narrow leaves and funnel-shaped yellow flowers, so delicately fragrant, and its small apple-like fruit; first green, then red to black. All parts are extremely poisonous; a single fruit can be fatal. It should not be planted where it might tempt small children.

MokWrightia religiosa – Don’t be deceived by this modest plant blooming all year-round with its graceful, slightly pendulous branches hung with rows of white, artless, bell-like flowers. All parts are poisonous.

Lan-tomPlumeria spp. – Frangipani. It has a poisonous milky sap which may inflame the skin and the eyes. 

Teen-phet-lekCerbera manghasPink-eyed Cerbera, an evergreen tree high on the toxic list. The bark is used to treat urinary stones; its stem bark produces a laxative; its white flowers treat hemorrhoids; the root is an expectorant; its leaf, used topically, treats ringworm; and fixed oil from the seed treats scabies. Seeds thrown into the water kill fish. Both latex and seed contain heart toxic properties. All parts cause vomiting and diarrhea; and a high dose may be fatal.

RakCalotropis giganteanCrown Flower, Giant Milkweed. The flower is used as a cough and asthma remedy. The stem latex is used as a purgative and applied topically for ringworm, it is also used to relieve toothache. Toxicity not established.

Yaem-pii-nang (Baan-thon)Strophanthus gratusCream Fruit, Indian Rubber Vine. Pinkish-violet, fragrant flowers. Though extremely poisonous, its seed does contain a cardiac stimulant. But its ambiguous toxicity makes it dubious as a herbal medicine. Toxic symptoms are nausea, diarrhea, and arrhythmia. If ingested, induce vomiting immediately and rush to hospital.

Dong-dueng (Daao-dueng)Gloriosa superbaClimbing Lily. Even low dose is toxic. Death in 3 – 20 hours.

SolanaceaeThe Deadly Nightshade family. Worldwide, it embraces an odd assortment of 2,950 mainly herbaceous species, some innocuous, nutritious, and with medical and commercial value. These include tomato, potato, eggplant, chilli pepper, bell pepper and tobacco. But as members of the Solanaceae family, all are closely related to some extremely poisonous black sheep, particularly Datura and Atropa (Belladonna).

Deadly Nightshade - Atropa belladonna - The plant has dull green leaves with an unctuous feel, and whitish, bell-shaped flowers yielding, small, shiny black berries. Apocryphal reports suggest that humans ingesting animals that have eaten the plant have been poisoned. All parts of the plant contain the extremely toxic alkaloid atropine (common name: belladonna). The approximate lethal dose for an adult is three berries, although fewer can be fatal. Symptoms of belladonna poisoning include dilation of pupils, tachycardia, hallucinations, blurred vision, loss of balance, a feeling of flight, staggering, a sense of suffocation, paleness followed by a red rash, flushing, husky voice, very dry throat, constipation, urinary retention, confusion, skin completely dry and sloughing off. Fatal cases have a rapid pulse that turns feeble.
Historically, women used belladonna to dilate their pupils using an extract in eye drops. It dilated the pupil to make eyes more attractive since pupils normally dilate when a person is aroused. To this day optometrists and ophthalmologists use belladonna in small doses to dilate the eye in examinations. Ironically, atropine is an effective treatment for Malathion poisoning and the infamous nerve gasses, Sarin and VX employed in war and feared in terrorist attacks.

Lam-phong-khaao - Datura suavevolensAngel’s Trumpet. Its trumpet-shaped white flowers, hanging down like pendent bells, contain a poisonous alkaloid, scopolamine. In properly controlled doses it produces hallucinations, but a mistaken dose can be fatal.