The alternate, compound leaves of Calpurnia sericea consist of three to thirteen leaflet pairs plus a terminal one (imparipinnate), the petiolules short.

Leaflet shape is elliptic, rounded at both ends, sometimes with a hair-like tip. The leaflet margins are entire, leaflets often overlapping. The finely hairy blades are deeper green on top than below, the midrib recessed on top. Leaflets are up to 2,5 cm long and 1,7 cm wide, the petiole plus the rachis up to 15 cm long.

C. sericea inflorescences grow fairly erect to slightly pendulous in terminal clusters. The flowers are small and yellow to orange-yellow, becoming brown. Flower structure is peaflower-like; the corolla bent outwards where it emerges from the calyx. The cup-shaped calyx is green and hairy with pointed lobes. The flowers are less than 6 mm long. Flowering happens in summer.

The flat pods are pale green, turning brown when ripe. They are from 1 cm to 5 cm long and from 0,3 cm to 1 cm wide (Coates Palgrave, 2002; Schmidt, et al, 2002; Pooley, 1998; iNaturalist).