The young branches of Albizia forbesii are grey with silvery or velvety hairs. Lenticels are usually seen but no spines.
The alternate, bipinnate leaves growing on short side-branchlets have two to seven pairs of pinnae that bear six to fourteen small oblong leaflets. The oblong leaflets with rounded, pointed or nearly square tips are close together and dark green, even slightly shiny on top. Lateral veins are sometimes prominent below. The leaflets in the pair at the end of the pinna are obovate in shape. Leaflets may be hairy on the lower surface along their midribs. There is no terminal pinna and no terminal leaflet. Leaflets become about 9 mm long and 2 mm wide.
Old leaves turn dark yellow before they fall. The rachis becomes up to 4 cm long, the hairy petiole up to 2 cm, bearing a gland (Coates Palgrave, 2002; Schmidt, et al, 2002; Van Wyk and Van Wyk, 1997; Pooley, 1993; iNaturalist).