Erect or spreading shrub to 2 m or so tall. Leaves mostly in whorls of 3 or 4, elliptic, occasionally ovate to lanceolate, to 3 cm long, 1 cm wide, with a sharp point. Flowers dense, axillary or terminal. Flowers with the corolla to about 1 cm long, yellow or orangish, sometimes with red dots, keel red. Fruit pod ovoid, about 8 mm long.
O. lanceolatum (Vent.) Druce, now Callistachys lanceolata Vent., Native Willow, from WA (naturalised in Vic) is occasionally grown; it is a shrub to 4 m tall with lanceolate leaves to 14 cm long and flowers in terminal clusters over 10 cm wide.
Source: (2002). Fabaceae. In: . Horticultural Flora of South-eastern Australia. Volume 3. Flowering plants. Dicotyledons. Part 2. The identification of garden and cultivated plants. University of New South Wales Press.