Calotropis gigantea

Pollination

This plant plays host to a variety of insects and butterflies. It is the host plant for Hawaii's non-migratory monarch butterflies. Calotropis 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 arranged in a structure named pollinia which are attached to a glandular, adhesive disc at the stigmatic angle (Translator Mechanism). These sticky discs get attached to the legs of visiting bees so that pollinia are pulled out when the bee moves away. When such a bee visits another flower, this flower gets pollinated by the sticky pollinium.

Uses

The flowers last long, and in Thailand they are used in various floral arrangements. The extract of flowers and leaves have shown hypoglycemic effect in preclinical studies. They were favored by the Hawaiian Queen Liliuokalani, who considered them a symbol of royalty and wore them strung into leis. While in Cambodia, they are used in funerals to decorate the urn or sarcophagus and the interior of the house holding the funeral. The fruit is a follicle and when dry, seed dispersal is by wind. In Indonesia its flowers are called widuri. According to Shivpuran (Hindu religion) madar flower /crown flower is very much liked by Lord Shiva therefore crown flower and its garland is offered to Lord Shiva for peace, prosperity and stability in society. Crown flower is also one of the major part of nine astrological trees (Navagrah tree). Crown flower cotton can also be used to make a pillow.

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 for stuffing purposes. Fermented mixture of Calotropis and salt is used to remove the hair from goat skins for production of "nari leather" and of sheep skins to make leather which is much used for inexpensive book binding. Fungicidal and insecticidal properties of Calotropis have been reported.

In India, the plant is common in the compounds of temples and is known as madar in Hindi: मदार. Its leaf (Marathi: rui) is one of the five leaves used in the Panch Pallava, a ritual assortment of five different leaves used as a totem by the Maratha culture in India.

It is known as වරා (waraa) in Sinhala, aakonda in Bengali, erukku (എരുക്ക്) in Malayalam and ark (अर्क) in Sanskrit.

Allelopathic effects

Allelopathic effects of Calotropis on different agricultural crops have been well studied. Extracts of plant parts such as root, stem, and leaf affect germination and seedling vigor of many agricultural crops. However, extracts of Calotropis failed to produce any detrimental effects on weeds such as Chenopodium album, Melilotus alba, Melilotus indica, Sphaeranthus indicus, and Phalaris minor.

Poisoning

Calotropis is a poisonous plant. The active principles are uscharin, calotoxin, calactin, and calotropin. The leaves and stem when incised yield thick milky juice. It is used as an arrow poison, cattle poison (see also Sutari), rarely for suicide and homicide and mostly an accidental 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

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.

Mosquito controlling property

C. gigantea is reported to exhibit mosquito controlling properties against Culex gelidus and Culex tritaeniorhynchus mosquitoes which serve as vectors for Japanese encephalitis. The aqueous extract of the C. gigantea leaves demonstrated significant larvicidal, repellent and ovicidal activity.