Dianthus micropetalus, locally known as grashout

The small flowers of Dianthus micropetalus are white or pink. They resemble tiny carnations, giving a clue about the plant's relations. There may be one or more flowers on each wiry erect stalk. The sepals are joined in a long green calyx tube with bracts at the base of the flower. Petals broaden towards the tips that have serrated edges; the lateral margins are entire. The flowers appear in spring and summer. 

The specific epithet, a Latin word, means small petals. A cluster of curving white stamens protrude from the flower in picture. This photo was taken in the Karoo near Beaufort West. The sepals have already turned brown on the flower.

Dianthus is a genus in the Caryophyllaceae or carnation family. There are more than 300 species in the genus, only 15 of them occurring in South Africa. Maybe the best known one is Dianthus mooiensis that is fairly common in Gauteng (Shearing and Van Heerden, 2008; iNaturalist).