downy seed fibre obtained from Calotropis procera and C. gigantea, plants of the Apocynaceae family. The plants are native to southern Asia and Africa and were introduced to South America and the islands of the Caribbean. The yellowish material is made up of thin fibres 2 to 3 cm (0.75 to 1.12 inches) long and 12 to 42 microns (a micron is about 0.00004 inch) in diameter and is harvested by hand. Akund floss is used primarily as upholstery stuffing, sometimes mixed with the seed fibre kapok. In certain areas it is variously known as ak, mader, or mudar.