The showy yellow flowers of Senna petersiana are scented, growing in lax sprays from stem-tips. An inflorescence is about 26 cm by 20 cm in size. The buds are globular, greenish yellow with one petal hidden inside.

There are five broad petals in the open flower with rounded tips and tapering bases. The five or more stamens are not all fertile. Flowering happens from midsummer to autumn or early winter, arriving with the new leaves on the late-deciduous tree.

Young green pod beginnings are visible in the photo (Coates Palgrave, 2002; Schmidt, et al, 2002; Pooley, 1993; iNaturalist).