The stalked flowers of Nemesia barbata grow in compact, few-flowered racemes. There is a small, green and hairy, five-lobed calyx at the back of the corolla.
The corolla is white or cream in parts and two-lipped. The upper lip is four-lobed, its small lobes round-tipped, the larger lower lip one-lobed and folded. In picture the outer surfaces of the four upper lobes are black, white on the inside.
On the lower lip there is a conspicuous forward patch that may be blue, dark blue, almost black or purple, while behind it is a smaller, raised band, conspicuously hairy and mostly lighter coloured. The specific name, barbata, is derived from the Latin word, barbatus, meaning bearded, referring to this hairy part at the base of the lower lip.
The blunt spur at the back of the corolla is about 2 mm long. Flower diameter is about 1 cm. There are four stamens in two unequal pairs.
Flowering happens from late winter to after midspring.
The fruit is a capsule, longer than it is wide (Vlok and Schutte-Vlok, 2015; Manning, 2007; Manning and Goldblatt, 1997; Bond and Goldblatt, 1984; iNaturalist).