The flowers of Justicia flava grow in spikes of about 12 cm long at the tips of the erect stems in closely spaced clusters. The many bracts around the flowers are narrowly lanceolate and very hairy, ascending around the flower stalk among the flowers. There are also stalked glands upon these bracts, augmenting the hairy appearance.

The two-lipped, yellow flower is tubular, the tube shorter than the lower lobe. The small upper lip is two-lobed, the large lower one three-lobed, 1 cm long and angled down like dog tongues after a run. The specific name, flava, comes from the flower colour, flavus meaning yellow (or orange) in Latin.

Flowering happens from late spring through summer and autumn (Pooley, 1998; Germishuizen and Fabian, 1982; Leistner, (Ed.), 2000; iSpot).