Calotropis procera

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.

Some biblical commentators believe that the ashkhar may have been the poisonous gourd (or poison-tasting gourd) that led to "death in the pot" in 2 Kings 4:38–41. In this story, a well-meaning servant of the prophet Elisha gathers herbs and many unknown gourds and casts them into the pot. After the outcry from the band of prophets, Elisha instructs them to cast flour into the stew pot, and they are saved.

In 1938, botanists Hannah and Ephraim HaReuveni, authors of "The Squill and the Asphodel" and parents of Noga Hareuveni, speculated that the עַרְעָ֣ר ʿaʿār was the ashkhar.

The fibre of the ashkhar may have been used for the linen of the High Priest of Israel.^{[citation needed]}

The fruit is described by the Roman Jewish historian Josephus, who saw it growing near what he calls Sodom, near the Dead Sea: "[A]s well as the ashes growing in their fruits; which fruits have a color as if they were fit to be eaten, but if you pluck them with your hands, they dissolve into smoke and ashes."

The ashkhar is listed in the Mishnah and Talmud. The fibers attached to the seeds may have been used as wicks. However, according to the Mishnah, it is one of the rabbinically prohibited activities of Shabbat.

In his Biblical Researches in Palestine, American biblical scholar Edward Robinson describes it as the fruit of the Asclepias gigantea vel procera, a tree 10–15 feet high, with a grayish cork-like bark called ʿosher by local Arabs. He says the fruit resembled "a large, smooth apple or orange, hanging in clusters of three or four." When "pressed or struck, it explodes with a puff, like a bladder or puff-ball, leaving only the shreds of the thin rind and a few fibers. It is filled chiefly with air, which gives it the round form, while in the center, a small, slender pod runs through it which contains a small quantity of fine silk, which local Arabs collect and twist into matches for their guns."