Growing as a spreading shrub or a small tree, Sodom's apple milkweed (Calotropis procera) has simple stems with only a few branches, which are light grey-green in colour and covered in a fissured, corky bark (3)(4)(5)(6)(7). The fairly large, grey-green leaves grow in opposite pairs along the stems and are smooth, with a pointed tip and heart-shaped base (2)(3)(4)(6)(7). The large, waxy, white flowers have deep purple spots or blotches at the base of each of the five petals, and are grouped in clusters, known as umbels(3)(4)(6)(7). Sodom's apple milkweed produces a simple, fleshy fruit in a grey-green inflated pod, containing numerous flat, brown seeds with tufts of long, white silky hair (‘pappus’) at one end. Sodom's apple milkweed exudes a milky white sap (latex) when the plant is cut or broken, which although toxic is widely used in many traditional medicines (2)(3)(4)(5)(6)(7).
Also known as
apple of Sodom, ashkhar, desert apple, giant milkweed, rubber bush, Sodom apple, Sodom's milkweed.
Sodom's apple milkweed is a perennial species (5) and flowering and fruiting occurs throughout the year, with each plant producing hundreds to thousands of seeds which are dispersed by the wind. After rainy periods, Sodom's apple milkweed seedlings will emerge in large numbers, although very few will grow to reach maturity (6). Cross-pollination occurs by insects, particularly by species such as the monarch butterfly (Danaus plexippus), which uses Sodom's apple milkweed as a host plant for various stages of its life cycle (2). The latex produced by Sodom's apple milkweed is toxic when ingested by mammals, affecting the heart, as well as causing nausea and vomiting (7).
Sodom's apple milkweed is native to much of Africa (excluding south and central Africa), the Arabian Peninsula and southern Asia. Sodom's apple milkweed has also been introduced, and is now naturalised, in Australia, many Pacific islands, Central and South America, South Africa and the Caribbean Islands (2)(3)(4)(6)(7)(8).
A drought-resistant, salt-tolerant species, Sodom's apple milkweed grows in open habitats and is particularly common in overgrazed pastures and on poor soils where there is little competition from grasses. Sodom's apple milkweed is also found along roadsides, watercourses, river flats and coastal dunes, and is often prevalent in disturbed areas (2)(3)(5)(6).
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