Indigofera suffruticosa
(Anil indigo)

Preferred Scientific Name

• Indigofera suffruticosa Mill.

Preferred Common Name

• Anil indigo

Other Scientific Names

• Anila tinctoria (L.) Kuntze
• Indigofera angolensis D. Dietr.
• Indigofera anil L.
• Indigofera argentea Sensu Baker
• Indigofera comezuelo DC.
• Indigofera divaricata Jacq.
• Indigofera drepanocarpa Bergman
• Indigofera guatimala Lunan
• Indigofera micrantha Desv.
• Indigofera oligophylla Lam.
• Indigofera tinctoria Lunan
• Indigofera uncinata G. Don

Local Common Names

• Chinese: ye qing shu
• English: Guatemala indigo
• French: indigotier sauvage
• Polynesia: aniles
• Spanish: anil; anil cimmaron; anil de pasto; azul auleiro; jiquelite
• Brazil: anil-dos-tintureiros; anileiro; caa-abi; caa-chica; guajan-timbe
• Cook Islands: 'initiko
• Fiji: vaivai
• Germany: mexikanischer indigostrauch; westindischer indigo
• India: vilaiti nit
• Indonesia: taem-taem; tagom-tagom; tom-janti
• Malaysia: sakebak; tarom
• Philippines: sangifaria; tayum; tina-tinaan
• Samoa: la'au failafo
• Sweden: vastindisk indigo
• Thailand: khram yaiuai; khram-thuan
• Tonga: 'akauveli
• USA/Hawaii: iniko; inikoa; kolu

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Fabales
•                         Family: Fabaceae
•                             Subfamily: Faboideae
•                                 Genus: Indigofera
•                                     Species: Indigofera suffruticosa

Linnaeus named this species as Indigofera anil in 1771 and this synonym is occasionally used, but Miller had earlier named it Indigofera suffruticosa and this name is now widely accepted. Many other synonyms have been applied, including I. tinctoria Lunan, which is now described as a distinct species (Plant List, 2013).

Paulino et al. (2010) suggest that I. anil and I. suffruticosa should not be synonymized as they differ from one another in both fruit morphology and foliar anatomy. I. anil also has larger seeds and acuminate-margined cotyledons. However, this species distinction is not accepted by other authorities.

Two subspecies are recognized in I. suffruticosa: subsp. suffruticosa and subsp. guatemalensis and up to ten varieties of the plant exist (Plant List, 2013; Prota4U, 2013).

A perennial herb or woody shrub up to 2 m high, erect greyish green with 2-branched hairs. Leaves imparipinnate, with up to 19 leaflets on a 1.5 cm petiole; leaflets up to 4 cm long, about 1 cm wide narrowly elliptical to obovate with a mucronate tip, almost glabrous above, grey above, paler, pubescent below. Stipules narrowly triangular, about 4 mm long. Inflorescence an axillary raceme, 2-6 cm long; bracts narrowly triangular; pedicel up to 1 mm long; corolla 4-5 mm long, salmon pink to red; calyx campanulate, 1 mm long, teeth triangular, 1 mm long; standard petal ovate to orbicular, 4 mm x 3 mm, brown-hairy on the back; wings 3 mm x 1 mm, glabrous; keel 3-4 mm x 1-2 mm, hairy; stamens 10, 1 free, 9 connate into a staminal tube 3-4 mm long; ovary hairy, style with capitate stigma. Stamens 3-4 mm long. Fruit a 4-8-seeded pod, distinctly up-curved, sickle-shaped, about 1.5 cm long x 2 mm, hairy. Seed cubical, 1.5-2.0 mm x 1.5 mm, shiny brown.

Details of floral development of I. suffruticiosa and related species are provided by Paulino et al. (2011).

The species was deliberately introduced to many countries, largely as a result of its common use as a source of indigo dye or for its medicinal properties. Introduction of Indigofera occurred into Europe many centuries ago; Luarca (1999) refers to documents indicating introduction of Indigofera anil or Indigofera tinctoria into Spain in 1565 or 1566. Other exact dates are lacking, but herbarium records indicate occurrences in Japan by 1915, Hawaii by 1916 and Australia by 1953.

Soil drainage

• free

Soil reaction

• neutral

Soil texture

• heavy
• light
• medium

Natural Dispersal (Non-Biotic)

I. suffruticosa has no specialized dispersal mechanism. The seeds are not even shed from the pods at maturity so the plant may depend on wind or water for dispersal.

Vector Transmission (Biotic)

No certain agents have been identified but the hard seeds may presumably survive passage through livestock or wild animals.

Accidental Introduction

Accidental introduction of the species is possible by introduction of contaminated forage crop seeds.

Intentional Introduction

Deliberate introduction is much less likely than in the past, as it is no longer widely used as a source of dye, but it is still a possible pathway if new medicinal uses are confirmed.

I. suffruticosa rarely occurs as a competitive weed, but when it forms dense thickets, pastures can be severely shaded and thus weakened. Problems usually arise following prolonged over-stocking during the dry season and domination by this weed from the next wet season onwards. Its dominance in pastures is assisted by the unpalatability of its foliage, causing livestock to avoid it (Oakes and Butcher, 1962).

Economic loss may also arise from its toxic properties. It can cause anaemia in cattle, sheep and goats (Figueiredo et al., 2012) and, despite spontaneous recovery by most cattle, death of some affected animals can occur by acute haemolytic anaemia (Salvador et al., 2010).

Impact on Biodiversity

Holm et al. (1979) classify it as a ‘principal’ weed in West Polynesia and common in Hawaii, Puerto Rico and Trinidad. It is recognised as invasive on many Pacific Islands, including Samoa, Hawaii, Tonga, the Cook Islands and Fiji (Space and Flynn, 2000, 2001; PIER, 2013). The plant may compete with native vegetation for space and light and may even replace some native species. It may also compete with some grassland species. In Hawaii, I. suffruticosa is among a number of introduced species which threaten the endangered species Panicum fauriei var. carteri, Spermolepis hawaiiensis and Wilkesia hobdyi (US Fish and Wildlife, 2010a, b; 2011).

• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Long lived
• Fast growing
• Has high reproductive potential
• Has propagules that can remain viable for more than one year

• Negatively impacts animal health
• Reduced native biodiversity
• Threat to/ loss of endangered species
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - shading
• Competition - smothering
• Competition (unspecified)
• Poisoning

• Highly likely to be transported internationally deliberately
• Difficult to identify/detect as a commodity contaminant

Economic Value

Originally, the species was used as an indigo producing dye plant in many tropical countries but now it is only cultivated for this purpose very locally in Java, India, Africa and Central America. Currently, I. suffruticosa is more important as a cover crop and green manure plant for coffee and tea in South and South East Asia, America and Africa. It is also used for contour hedges and in folk medicine (Mansfeld's World Database of Agricultural and Horticultural Crops, 2013).

Sandoval-Salas et al. (2006) studied production of the dye in Mexico and concluded maximum yield was obtained 150 days after sowing.

I. suffruticosa, used as mulch can suppress nematodes in USA (Morris et al., 2002)

It is rated as a good nitrogen-fixer in Venezuela (Izaguirre-Mayoral et al., 1996).

Social Benefit

In Brazilian folk-medicine it is used for gastric disorders, infection and inflammation, acting as a gastro-protective agent, stimulating prostaglandin, mucus and HSP70 (Luiz-Ferreira et al., 2011). A small extract of I. suffruticosa was effective in controlling head-lice in Cuba (Garcia Calixto et al., 2011).

Aqueous extracts of the leaves of I. suffruticosa, obtained by infusion, can be used in the treatment of skin diseases caused by dermatophytes (Leite et al., 2006); also against stomach-ache, fever and diarrhoea in Malaysia (PROSEA, 2013). Francis (2013) refers to uses for fever, headaches, haemorrhage, convulsions, coughs, skin parasites and boils.

In China, a mixture of leaves of Indigofera tinctoria or I. suffruticosa, the bark of Phellodendron chinense and pig bile is used to treat scrofula (tuberculosis of the cervical lymph nodes) (Liu and He, 1991). Carli et al. (2010) also suggest that I. suffruticosa extracts may have an important immunological role in the control of tuberculosis once macrophage activity has been induced by them.

The immuno-stimulatory and cytotoxic activity of I. suffruticosa, enhances macrophage function and contributes to host defences against tumours (Lopes et al., 2011) and Vieira et al. (2007) found it highly effective in inhibiting the growth of solid tumours (sarcoma) in mice.

However, Leite et al. (2004) warn that the plant can have damaging effects on the foetus in rats and could be hazardous in humans. The alkaloid fraction of I. suffruticosa contains indigo and indirubin, and indigo has been found responsible for the mutagenic activity in a Salmonella/microsome assay (Calvo et al., 2011).

I. suffruticosa has been found to negatively affect the early development of mosquitoes. Vieira et al. (2011) found that extracts of the plant showed repellent activity, specific embryotoxicity, and general growth retardation in the mosquito Aedes aegypti.

Environmental Services

USDA-ARS (2013) refers to its use for erosion control and a soil improver.