Hereroa aspera produces fragrant yellow flowers in spring and summer, pollinated by moths. The narrow petals that grow in more than one whorl have a reddish colour upon their outer surfaces. There are five somewhat unequal sepals around the base of the petals and five thread-like stigmas, longer than the stamens.

The fruit capsules, some of which are present in the photo have five locules covered by tiny closing bodies.

The Afrikaans vernacular name of this (and some other Hereroa vygies) is slaapvygie (sleep mesemb), referring to the flower opening times. Slaapvygies open late in the afternoon or only in the evening, when the flowers of many other plant species tend to close. The later they open, the stronger usually the flower fragrance (Vlok and Schutte-Vlok, 2010; Smith, et al, 1998; www.redlist.sanbi.org).