Calotropis gigantea

bowstring hemp


Calotropis gigantea

(L.) Dryand. 1811

pronounced: kal-LOW-troh-piss gy-GAN-tee-uh

(Apocynaceae — the oleander family)


common names: bowstring hemp, giant rubber bush, king's crown

Calotropis comes from the Greek καλος (kalos), beautiful, and τροπις (tropis), a ship’s keel; gigantea is Latin, giganteus, of or belonging to the giants.

This plant originated in Indonesia, Malaysia, the Philippines, Thailand, Sri Lanka, India and China. It is a large shrub that can grow to 4 m tall. The plant has opposite light green leaves, with short petioles and a heart-shaped base. They are stiff, leathery and waxy, elliptic in shape, 8 – 20 cm long and 4 – 12 cm wide, with a pointed apex.

The plant has clusters of waxy flowers that are either white or lavender in colour. Each flower consists of 5 pointed petals and a small elegant ‘crown’ rising from the centre, which holds the stamens.

The fruits are bluish green, 7 – 10 cm long and up to 4 cm thick. They are bent at the bottom and have many seeds, each one with a hairy tuft. They are wind-dispersed.

This plant plays host to a variety of insects, and is a food plant for the caterpillars of several Lepidoptera, including the Wanderer Danaus plexippus and the Lesser Wanderer Danaus chrysippus.

The petioles supply a tough, durable fibre, used for making ropes, carpets, fishing nets and sewing thread. The poisonous milky sap has many medicinal applications. When dry, it turns into a rubber-like substance. The flowers stay fresh for a long time, and are popular in flower arrangements. In Thailand, they are strung into garlands and used in wedding ceremonies. They are also reputed to have been very popular with the Hawaiian Queen Liliuokalani, who considered them a symbol of royalty. In India, the plant is commonly found in temple compounds, and is known as madar. In many places it is a roadside weed.

In India, Calotropis is used alone or with other herbs to treat common diseases such as fevers, rheumatism, indigestion, coughs, colds, eczema, asthma, elephantiasis, nausea, vomiting and diarrhoea. In Ayurveda medicine, the whole plant, dried, is prepared in various ways and used as a tonic, an expectorant, to remove impurities from the blood, and as a vermifuge. The dried root bark is used as a substitute for ipecacuanha. The root bark is a febrifuge and a laxative. It also has a digitalis-like effect on the heart. The powdered root is used to treat asthma, bronchitis and dyspepsia. The leaves are used in the treatment of paralysis, arthralegia, swellings, and intermittent fevers. The flowers are bitter, digestive, astringent, stomachic, anthelmintic and tonic. Calotropis is also used in homoeopathic medicine.

dangerous 2If poisoning follows any internal application of the plant, atropine is often administered as an antidote.

Floss, obtained from the seeds, is used for stuffing purposes. A fermented mixture of the plant and salt is used to remove the hair from goat skins for the production of nari leather, and from sheep skins to produce a leather which is much used for inexpensive bookbinding. What a useful plant this is! It is no wonder that an enterprising gardener in Nelly Bay has planted some in his or her garden!


I do not know the reason for the reference to the ship’s keel
a Brazilian plant, whose name comes from the Tupi i-pe-kaa-guéne, which translates to “road-side sick-making plant”.


Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.


Photographs taken in Nelly Bay 2009, 2010, & Picnic Bay 2015
Page last updated 27th October 2018