ระว่านงู (Ra Wan Ngu)
Family: Apocynaceae
Rauvolfia serpentina, known in Thai as ระว่านงู (Ra Wan Ngu) and internationally as Indian Snakeroot or Serpentwood, is a small evergreen shrub native to South and Southeast Asia. It has been revered for centuries as a potent calming herb used to treat hypertension, anxiety, and insomnia. The plant’s roots contain powerful alkaloids, including reserpine, which became a cornerstone compound in early modern medicine for blood pressure management.
Botanical Characteristics
This shrub typically grows between 60 cm and 1.5 meters tall, with smooth, pale bark and whorled leaves arranged in clusters of three to five. The leaves are glossy, dark green, and lanceolate with a pronounced midrib. Small white to pinkish flowers form in terminal clusters, followed by small red to black drupes. It thrives in warm, humid climates and prefers shaded or partially shaded environments with well-drained soil.
Use in Thai Traditional Medicine
In Thai herbal medicine, ระว่านงู is considered a cooling and sedative herb. The dried root is used in small doses to calm the nervous system, reduce high blood pressure, and ease restlessness or insomnia. It is also prescribed for anxiety, stress, and circulatory imbalance. Due to its potency, it is often combined with milder herbs such as ใบเตย (Pandan leaves) or บัวหลวง (Lotus) to create balanced tonics. The root extract has historically been used for snakebite treatment, giving the plant its Thai name “snake herb.”
Cultivation Notes
Rauvolfia serpentina grows best in partial shade with moist, fertile, well-drained soil. Overharvesting of wild populations has made cultivation important for conservation. The KBE Thai Medicinal Herb Garden maintains this species as part of its living collection of high-value medicinal shrubs, emphasizing sustainable use and traditional preservation.
Historical Context
This species holds a unique place in global pharmacology: the alkaloid reserpine, first isolated from Rauvolfia in the 1950s, revolutionized the treatment of hypertension and certain psychiatric conditions. In Thailand, it remains respected as a gentle, natural means of calming the heart and mind — a plant that bridges traditional wisdom and modern science.
Disclaimer: This information is provided for educational and historical purposes only. It is not intended as medical advice. Always consult a qualified healthcare professional before using any herbal preparation.
