The inflorescence of Setaria megaphylla is a panicle of spikes and spikelets comprising tiny florets, subtended by persistent, but inconspicuous bristles and some spines. They start off cream coloured, later becoming maroon to brownish and shiny as in the photo. The perianth is only small scales, the ovary superior.

Flowering occurs in autumn (Lowrey and Wright, 1987; Van Oudtshoorn and Van Wyk, 1991; www.plantzafrica.com).