Continuing with the "Tropical Biodiversity" series theme, today's image was taken in western India by dinesh_valke@Flickr (aka Dinesh Valke). Thank you! I've cropped the original image a bit in order to show additional detail on the flowers (image via the Botany Photo of the Day Flickr Pool).
With the sinking of the milkweed family (Asclepiadaceae) into the dogbane family, Apocynaceae now includes over 400 genera and 4500 species. The genus Calotropis contains only two of these species: today's featured species and Calotropis procera.
Calotropis gigantea is native to much of southern tropical Asia and parts of warm temperate Asia, reaching as far west as Iran. Common names abound for this species, including bowstring-hemp, crownplant, and giant-milkweed in English and madar in Hindi. It is considered a "useful weed". "Weed" in this instance refers to its ability to grow in "waste" places or areas of significant disturbance, whereas useful alludes to its value in fibre production (or perhaps traditional medicine, though it contains a few nasty toxins).
An excellent account of the cultural history and economic uses of Calotropis gigantea was written by George Watt in 1900, though I'm not sure if all BPotD readers will be able to access this link: Madar. Calotropis gigantea R. Br., from the Bulletin of Miscellaneous Information (Royal Gardens, Kew), Vol. 1900.
Like yesterday's taxon, Calotropis gigantea has naturalized in Hawaii, and Plants of Hawaii has another extensive image collection (including the use of flower blossoms in the creation of leis): Calotropis gigantea.