Species Details

Details of Giant Milkweed will be displayed below

Giant Milkweed   

Common Name: Bowstring hemp, Crown fl ower, Giant calotrope, Milkweed, Ivory Plant, Swallow-wort
Scientific Name: Calotropis gigantea
Local Name: Ruvaa
Dhivehi Name: ރުވާ
Plantae  (Kingdom)
Tracheophyta  (Plylum)
Magnoliopsida  (Class)
Gentianales  (Order)
Apocynaceae  (Family)
Calotropis   (Genus)

Giant Milkweed's description

It is a large shrub and has clusters of waxy flowers that are either white or lavender in colour. Each flower consists of five pointed petals and a small "crown" rising from the center which holds the stamens. The aestivation found in calotropis is valvate i.e. sepals or petals in a whorl just touch one another at the margin, without overlapping. The plant has oval, light green leaves and milky stem.

Plant Morphology : Growth Form: Medium to big shrub with stout rangey form, up to about 4m height when planted in ground. Foliage: Leaves large, thick, tomentose-velvety, pale silvery-green with powdery bloom on both surfaces. Fruits: Fleshy capsules, curved and somewhat horned-shaped, ripening from green to yellowish-brown, and splitting apart to reveal small lightweight seeds with fine woolly hairs which assist in dispersal by wind.

Giant Milkweed's facts

Did you know?

  • The latex of Calotropis gigantea contains cardiac glycosides, fatty acids, and calcium oxalate.
  • Giant Milkweed (Calotropis gigantea) is a great caterpillar Food Plant.

Giant Milkweed's Behavior & Ecology

In Maldives it is common in open areas, this plant prefers dry coastal areas, along the sheltered shores of lagoons, overgrazed pasture land. Woods of dry areas, stream banks from sea level to 1,400 metres.

Giant Milkweed's Reproduction

This plant plays host to a variety of insects and butterflies. It is the host plant for Hawaii's non-migratory monarch butterflies. This plant is an example of entomophily pollination (pollination by insects) and pollination is achieved with the help of bees. In Calotropis, gynostegium is present (formed by the fusion of stigma and androecium). The pollen are in a structure named pollinia which is attached to a glandular, adhesive disc at the stigmatic angle (translator mechanism). These sticky discs get attached to the legs of visiting bees that pull out pollinia when a bee moves away. When such a bee visits another flower, this flower might be pollinated by the pollinium.

Giant Milkweed's Relationship with Humans

The flowers are long lasting, and in some arean in world flowers are used in floral arrangements in different occations. Calotropis yields a durable fiber (commercially known as bowstring of India) useful for ropes, carpets, fishing nets, and sewing thread. Floss, obtained from seeds, is used as stuffing. Crown flower cotton can also be used to make a pillow. A fermented mixture of Calotropis and salt is used to remove the hair from goat skins for production of nari leather and from sheep skins to make leather which is much used for inexpensive book binding.

Medicinal: All parts of plants considered to be medicinally effective but keep in mind that all parts of the plant are toxic. 


Giant Milkweed (Calotropis gigantea) is a poisonous plant. The active principles are uscharin, calotoxin, calactin, and calotropin. The leaves and stem when incised yield thick milky juice which is poison. The milky latex sap of Calotropis gigantea is a known cause of toxic keratoconjunctivitis and reversible vision loss. Crownflower keratitis is a rare condition and is usually the result of accidental ocular exposure to the sap. During the process of making a Hawaiian lei flower necklace, touching the sap and then touching the ocular surface may result in crownflower keratitis. Damage (poisoning) of the cornea endothelium results in corneal stromal edema and decreased visual acuity. Although there is some permanent damage to the corneal endothelium with decreased endothelial cell count and irregular shape, the remaining corneal endothelial cells usually recover with complete resolution of the corneal edema and a return to normal visual acuity. The condition is usually self-limited and resolves faster with topical steroids. The clinical course of this condition suggests that Calotropis is paradoxically relatively nontoxic to corneal epithelium and highly toxic to corneal endothelium. The painless clinical course may be related to anesthetic properties of Calotropis latex and relatively minor epithelial injury.

Signs and symptoms of poisoning

Applied to the skin, it causes redness and vesication. When taken orally, the juice produces an acrid, bitter taste and burning pain in throat and stomach, salivation, stomatitis, vomiting, diarrhea, dilated pupils, tetanic convulsions, collapse and death. The fatal period is 6 to 12 hours.

Treatment includes stomach wash, demulcents, and symptomatic treatment.