creeping indigo

Indigofera spicata
infestation growing in a lawn (Photo: Sheldon Navie)
spreading habit growing on a creek-bank (Photo: Sheldon Navie)
habit in flower (Photo: Sheldon Navie)
habit in fruit (Photo: Sheldon Navie)
once-compound leaves with several leaflets (Photo: Sheldon Navie)
close-up of leaves with alternately arranged leaflets (Photo: Sheldon Navie)
elongated flower cluster (Photo: Sheldon Navie)
close-up of pinkish-coloured pea-shaped flowers (Photo: Sheldon Navie)
clusters of backwards-pointing immature fruit (Photo: Sheldon Navie)
mature fruit (Photo: Sheldon Navie)
seedling (Photo: Sheldon Navie)
Herb
Alternate
Compound
Pink
Green

A short-lived herbaceous plant with creeping or scrambling stems. Its alternately arranged leaves are once-compound with 5-11 leaflets these oblong leaflets (5-25 mm long) have hairless or sparsely hairy upper surfaces and densely hairy undersides. Its small pink or pinkish-orange pea-shaped flowers (4-5 mm long) are arranged in elongated clusters up to 10 cm long its narrow cylindrical pods (15-25 mm long) are borne in a backwards facing position.

Common names 
Also known as: creeping indigo, indigo, indigo bush, lawn indigo, trailing indigo,
Family 
Fabaceae
Deciduous 
No
Flowering time 
Year round
Native/Exotic 
Exotic
Origin 
Native to Africa.
Notifiable 
No
Council declaration 
SIL – Special Investigation List
Known distribution 

Widely naturalised in the coastal districts of south-eastern Queensland, and particularly common in the Moreton district. Also occasionally naturalised in the coastal districts of central and northern Queensland. Possibly also naturalised in the northern parts of the Northern Territory.

Habitat 

A very common weed of lawns, gardens, footpaths, roadsides, disturbed sites and waste areas.

Habit 

A short-lived (i.e. annual) herbaceous plant with creeping (i.e. prostrate) or scrambling stems.

Impact and control methods 
Stem and leaves 

The stems are slightly flattened, and sparsely hairy (i.e. puberulent). The alternately arranged leaves are once-compound (i.e. pinnate) with 5-11 alternatively arranged leaflets. Their leaflets (5-25 mm long and 4-10 mm wide) are oblong in shape with entire margins. These leaflets are hairless (i.e. glabrous) or sparsely hairy (i.e. puberulent) on the upper surface, while their undersides are densely covered with small close-lying hairs (i.e. appressed pubescent).

Flowers and fruits 

The small pea-shaped flowers (4-5 mm long) are pink or pinkish-orange in colour. They are arranged in elongated clusters (i.e. spike-like racemes) up to 10 cm long. Each flower has a larger upper petal (i.e. standard), two side petals (i.e. wings) and two lower petals that are fused together and folded (i.e. a keel). The flowers also have ten stamens and an elongated ovary topped with a style and stigma. The fruit are cylindrical pods (15-25 mm long) that turn from green to dark brown in colour as they mature. These fruit are borne in a backwards facing position (i.e. they are deflexed) and are sparsely hairy (i.e. puberulent).

Reproduction and dispersal 

This species reproduces by seed, which are probably dispersed by mowers and in contaminated soil. They may also be spread by water and in mud attached to animals and vehicles.

Similar species 

Creeping indigo (Indigofera spicata) is very similar to the introduced Indigofera circinella and relatively similar to the native hairy indigo (Indigofera hirsuta). These species can be distinguished by the following differences: creeping indigo (Indigofera spicata) has mostly creeping (i.e. prostrate) stems, and its stems and leaves are covered in close-lying hairs (i.e. appressed pubescent). Its cylindrical fruit are straight and borne in a backwards facing position (i.e. they are reflexed) Indigofera circinella has mostly creeping (i.e. prostrate) stems, and its stems and leaves are hairless (i.e. glabrous) or covered in close-lying hairs (i.e. appressed pubescent). Its cylindrical fruit are strongly curved or coiled hairy indigo (Indigofera hirsuta) has spreading or upright (i.e. erect) stems, and its stems and leaves are covered in spreading hairs (i.e. they are hirsute). Its cylindrical fruit are straight and borne in a backwards facing position (i.e. they are reflexed). Creeping indigo (Indigofera spicata) is also similar to Birdsville indigo (Indigofera linnaei) and narrow-leaved indigo (Indigofera linifolia). However, these native species have much smaller pods (less than 7 mm long), and narrow-leaved indigo (Indigofera linifolia) leaves have only a single leaflet.