Leaves alternate, simple, 1- or 3-foliolate, or imparipinnate with 5-many leaflets; leaflets entire, usually opposite; stipules present, sometimes spinescent.
Inflorescences axillary racemes. Calyx teeth subequal or the lowermost longer. Corolla red, pink or purple. Stamens diadelphous (9 fused ± 1 free); anthers apiculate. Ovary usually pubescent; style glabrous, stigma capitate; ovules 1, 2 or numerous.
Pods globose to linear and terete; mostly several-seeded, with seeds separated by membranous or pithy outgrowths of the endocarp.
| | Key to the species | |
| 1 | Leaves simple | 2 |
| Leaves compound, sometimes appearing simple through loss of leaflets | 3 |
| 2 | Pods globose; inflorescences ≤1 cm long | Indigofera linifolia |
| Pods ± linear and terete; inflorescences 1.5–3 cm long
Back to 1 | Indigofera triflora |
| 3 | Leaflets alternate on the rachis; stipules lanceolate with scarious margins | 4 |
| Leaflets usually opposite; stipules linear to triangular, margins not scarious, sometimes spinescent
Back to 1 | 5 |
| 4 | Pod short, usually <10 mm long; seeds usually 2; inflorescence usually ≤20 mm long | Indigofera linnaei |
| Pod 10–18 mm long; seeds 4–8; inflorescence ≥30 mm long
Back to 3 | Indigofera spicata |
| 5 | Pods bearing relatively long stiff hairs or erect gland-tipped hairs | 6 |
| Pods tomentose, appressed-hairy, or ± glabrous
Back to 3 | 7 |
| 6 | Pods deflexed, covered with stiff, spreading hairs | Indigofera hirsuta |
| Pods not deflexed, bearing erect gland-tipped hairs amongst the appressed hairs
Back to 5 | Indigofera colutea |
| 7 | Pods straight | 8 |
| Pods crescent-shaped
Back to 5 | Indigofera suffruticosa |
| 8 | Pods ± glabrous or with scattered, appressed hairs | 9 |
| Pods densely appressed-hairy, or tomentose
Back to 7 | 16 |
| 9 | Stipules 4–7 mm long, persistent and spinescent | Indigofera helmsii |
| Stipules ≤4 mm long, never spinescent, sometimes persistent
Back to 8 | 10 |
| 10 | Leaf rachis flattened, 1–4 mm wide; leaves sometimes appearing simple through loss of leaflets | 11 |
| Leaf rachis ± terete; leaflets persistent
Back to 9 | 12 |
| 11 | Plant whitish in appearance; leaves with 5–9 leaflets | Indigofera efoliata |
| Plant green in appearance; leaves with 9–23 leaflets
Back to 10 | Indigofera adesmiifolia |
| 12 | Branchlets white with a dense tomentum | Indigofera coronillifolia |
| Branchlets greyish with appressed hairs or ± glabrous
Back to 10 | 13 |
| 13 | Plants shrubby, at least 1 m high | 14 |
| Plants arising from underground rootstocks or rhizomes, usually <1 m high
Back to 12 | 15 |
| 14 | Plants dark green in appearance; hairs on calyx dark brown, hairs on back of standard white | Indigofera australis |
| Plants grey in appearance; hairs on calyx and back of standard usually golden-brown
Back to 13 | Indigofera brevidens |
| 15 | Aerial stems weak and slender; flowers 4–7 mm long | Indigofera baileyi |
| Aerial stems woody; flowers 14–17 mm long
Back to 13 | Indigofera decora |
| 16 | Leaves grey-green; inflorescences at least twice as long as the leaves | Indigofera psammophila |
| Leaves grey or white with dense hairs; inflorescences less than twice as long as the leaves
Back to 8 | 17 |
| 17 | Leaves white; leaflets 9–13; inflorescences 3–6 cm long | Indigofera leucotricha |
| Leaves grey; leaflets 15–21; inflorescences 6–16 cm long
Back to 16 | Indigofera longibractea |
