Calotropis procera is a species of flowering plant in the family Apocynaceae that is native to Northern and Tropical Africa, Western Asia, South Asia and Indochina (mainland Southeast Asia). It typically reaches a height between 6 feet (1.8 m) to 8 feet (2.4 m), and rarely to as high as 15 feet (4.6 m), and grows in sunny to partly-shaded habitats such as disturbed and overgrazed lands, rangeland, roadsides, river flats and coastal dunes. Its green fruits contain a toxic milky sap that is extremely bitter and turns into a latex-like substance, which is resistant to soap.
Common names for the plant include Apple of Sodom, Sodom apple, roostertree, king's crown, small crownflower, giant milkweed, rubber bush, and rubber tree. The names "Apple of Sodom" and "Dead Sea Apple" stem from the ancient authors Josephus and Tacitus, who described the plant growing in the area of biblical Sodom. Although not native to the New World, the plant (and other related milkweed species) has been cultivated, and feeds monarch butterfly caterpillars, in places such as California, Hawaii and the island of Puerto Rico. In Arabic, it is known as al-ashkhar.