akund floss, downy seed fibre obtained from Calotropis procera and C. gigantea, milkweed plants of the Apocynaceae family (formerly in Asclepiadaceae). Small trees or shrubs, these two species are native to southern Asia and Africa and were introduced to South America and the islands of the Caribbean, where they have naturalized. The yellowish material is made up of thin fibres 2 to 3 cm (0.8 to 1.2 inches) long and 12 to 42 microns (a micron is about 0.00004 inch) in diameter and is harvested from the seeds by hand. While akund floss has been used primarily as upholstery stuffing and is sometimes mixed with the seed fibre kapok, it has development potential as a new ecological material.