Eriocephalus purpureus is a branched shrub with small, mauve flowerheads and white woolly fruit.
Most of the Eriocephalus bushes bear flowerheads with few white ray florets and red to purple discs in the centre. Only two or three rays grow from an E. purpureus flowerhead. The receptacle has scales, the outer ones woolly, tending to cover the outer florets.
Once the flowering is over, the outer layer of woolly fruit looks much the same as on its generic compatriots, the heads covered in wool completely (Manning, 2007; Bond and Goldblatt, 1984; iNaturalist; JSTOR).