The stem-tip flowerheads of Gorteria alienata have one row of spreading, three-tipped, yellow ray florets around a compact disc of tiny, tubular, yellow florets ending in five corolla lobes. The rays are dark brown on their lower surfaces. The heads are about 3 cm in diameter. Anthers or styles are exserted when ripe from the disc florets.
The green involucre below and around the floret bases consists of about five or six rows of narrow, bristly and acutely pointed bracts that veer away from the head in their upper parts.
Flowering happens from late winter to early summer after rain (Van Rooyen and Van Rooyen, 2019; Vlok and Schutte-Vlok, 2015; Bond and Goldblatt, 1984; iNaturalist).