Indigofera suffruticosa
(Anil indigo)

Pictures

Picture	Title	Caption	Copyright
Title Habit Caption Indigofera suffruticosa (upright indigo); habit. Paia, Maui.April 16, 2006 Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Habit	Indigofera suffruticosa (upright indigo); habit. Paia, Maui.April 16, 2006	©Forest Starr & Kim Starr - CC BY 4.0
Title Habit and foliage Caption Indigofera suffruticosa (upright indigo); habit and foliage. Mokolii, Oahu. April 19, 2005 Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Habit and foliage	Indigofera suffruticosa (upright indigo); habit and foliage. Mokolii, Oahu. April 19, 2005	©Forest Starr & Kim Starr - CC BY 4.0
Title Leaves Caption Indigofera suffruticosa (upright indigo); leaves. Kipahulu LZ Haleakala National Park, Maui. February 24, 2009 Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Leaves	Indigofera suffruticosa (upright indigo); leaves. Kipahulu LZ Haleakala National Park, Maui. February 24, 2009	©Forest Starr & Kim Starr - CC BY 4.0
Title Flowers Caption Indigofera suffruticosa (upright indigo); flowers. Wailea 670, Maui. February 02, 2003 Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Flowers	Indigofera suffruticosa (upright indigo); flowers. Wailea 670, Maui. February 02, 2003	©Forest Starr & Kim Starr - CC BY 4.0
Title Immature fruits Caption Indigofera suffruticosa (upright indigo); immature fruits. Paia, Maui. April 16, 2006 Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Immature fruits	Indigofera suffruticosa (upright indigo); immature fruits. Paia, Maui. April 16, 2006	©Forest Starr & Kim Starr - CC BY 4.0
Title Mature seed pods Caption Indigofera suffruticosa (upright indigo); mature seed pods. Kula, Maui. December 01, 2006 Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Mature seed pods	Indigofera suffruticosa (upright indigo); mature seed pods. Kula, Maui. December 01, 2006	©Forest Starr & Kim Starr - CC BY 4.0
Title Mature seed pods Caption Indigofera suffruticosa (upright indigo); fully mature seedpods, note black seeds still present in some pods. Kipahulu LZ, Haleakala National Park, Maui. February 24, 2009 Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Mature seed pods	Indigofera suffruticosa (upright indigo); fully mature seedpods, note black seeds still present in some pods. Kipahulu LZ, Haleakala National Park, Maui. February 24, 2009	©Forest Starr & Kim Starr - CC BY 4.0

Identity

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

• : anil; anil cimmaron; anil de pasto; azul auleiro; jiquelite
• : aniles
• : Guatemala indigo
• : indigotier sauvage
• : ye qing shu
• 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

Summary of Invasiveness

I. suffruticosa, a perennial herb or woody shrub, is native to the Americas but has been widely introduced elsewhere as a source of dye and for medicinal purposes and has commonly become naturalized. It tolerates a range of soil types and may become dominant in disturbed habitats. It is now classed as invasive on many Pacific Islands including Hawaii, Samoa, Tonga, the Cook Islands and Fiji (Space and Flynn, 2000, 2001; PIER, 2013). Holm et al. (1979) classify it as a ‘principal’ weed in West Polynesia and common in Hawaii, Puerto Rico and Trinidad. It is not often a weed of crops but tends to replace native vegetation. In Hawaii it threatens the endangered species Panicum fauriei var. carteri, Spermolepis hawaiiensis and Wilkesia hobdyi (US Fish and Wildlife, 2010a, b; 2011).

Risk assessment index for Australia is 6 ('more information needed'); for the Pacific Islands it is 11 ('high') (PIER, 2013).

Taxonomic Tree

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

Notes on Taxonomy and Nomenclature

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).

Description

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).

Plant Type

Distribution

The native distribution of I. suffruticosa extends across the Americas from the southern USA to Argentina, with heaviest occurrence in the tropical Caribbean and Central America. Largely as a result of deliberate introduction as a dye-plant it now occurs widely in Africa, Asia and the Pacific, and also Australia.

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

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.

Introductions

Risk of Introduction

The risk of further introduction is low but not insignificant, as deliberate introduction could still be of interest. It may also occur as a contaminant of forage crops seeds.

Habitat

The plant can be found on roadsides, bush fallow, pastures, clearings, and other disturbed areas in the tropics, sub-tropics and warm temperate conditions. It occurs in a wide variety of soils including those of low fertility, and will grow in areas of full sunlight or partial shade. However, it will not tolerate full shade. It can occasionally be found in wetlands (USDA-NRCS, 2013).

Habitat List

Hosts/Species Affected

Various grassland species may be affected by the presence of I. suffruticosa. There are few records of occurrence in annual crops, though it may occur as a minor component of the weed population in young forest or plantation crops. PROSEA (2013) record that it may occasionally overgrow young tea plants but it can be easily removed.

Biology and Ecology

Genetics

Chromosome number is usually given as 2n = 16, but there can be sporadic tetraploidy with 2n = 32 (Missouri Botanic Garden, 2013; Prota4U, 2013).

Reproductive Biology

Flowering occurs after 4-5 months. Some seeds may germinate spontaneously within a few months but I. suffruticosa has hard seeds which need alternating temperatures with or without wet-dry cycles (Moreno-Casasola, et al., 1994; Francis, 2013; Kew Royal Botanic Gardens, 2013). Germination of scarified seeds is high at temperatures from 15°C to 33°C (Kew Royal Botanic Gardens, 2013).

Physiology and Phenology

Seedlings show epigeal germination and the first leaves to be formed are simple. Flowering occurs within 4-5 months. Nodulation allows it to thrive in low-fertility soils.

Longevity

Kew Royal Botanic Gardens (2013) records long survival of seeds in dry storage and it is assumed they may also persist for many years in the field. The established plants persist for a few seasons but die out if regularly cut or grazed.

Nutrition

I. suffruticosa fixes nitrogen and does not need fertile soils.

Environmental Requirements

The plant thrives in tropical and sub-tropical conditions and is able to tolerate a range of soil conditions, provided they are well-drained and not too shaded.

US hardiness zones are given as 5-9 (eHOW, 2013).

Climate

Latitude/Altitude Ranges

Air Temperature

Rainfall

Soil Tolerances

Soil drainage

• free

Soil reaction

• neutral

Soil texture

• heavy
• light
• medium

Natural enemies

Notes on Natural Enemies

No serious diseases or pests have ever been reported to attack I. suffruticosa. In humid conditions Corticium salmonicolor sometimes affects the stems after slashing (PROSEA, 2013) and Cannon (1999) reports susceptibility to the fungus Parodiella hedysari.

Predation by the lepidopteran Anticarsia gemmatalis occurs in Brazil (Panizzi et al., 2004), while another, Gesta gesta, is believed to predate specifically on species of Indigofera (Francis, 2013).

Means of Movement and Dispersal

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.

Pathway Causes

Pathway Vectors

Impact Summary

Economic Impact

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).

Environmental Impact

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).

Threatened Species

Risk and Impact Factors

• 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
• Poisoning

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

Uses

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.

Uses List

Environmental

• Erosion control or dune stabilization
• Soil conservation

Materials

• Dyestuffs
• Green manure
• Mulches

Medicinal, pharmaceutical

• Traditional/folklore

Similarities to Other Species/Conditions

The closely related species Indigofera tinctoria, which has also been used as a source of indigo dye, is distinguished by its larger and less numerous leaflets and its pods being somewhat straighter and longer (2.5-3.0 cm with 5-8 seeds), and stamens longer (4-5 mm) than those of I. suffruticosa. Another similar species, Indigofera arrecta, has straight pods with no more than 6 seeds.

Leite et al. (2009) describe how I. suffruticosa can be distinguished from other species in Brazil, including Indigofera truxillensis, by its fruit characters; similarly, on the basis of trichome characters (Marquiafável et al., 2009).

Prevention and Control

Physical/Mechanical Control

Seedlings are readily controlled by hoeing. Established plants have a deep root system but do not regenerate from below ground so may be controlled by suitable cultivation.

Biological Control

No known attempts have been made at biological control.

Chemical Control

In Vanuatu, a triclopyr/picloram mixture is recommended to be applied to young growth after slashing to 30-40 cm height and wetting of foliage is important. However, spraying is pointless where there is not an adequate under-storey of native or improved grass and legume, and if not, recommended pastures should be sown (FAO, 2013). 

Gaps in Knowledge/Research Needs

There is a general lack of detailed information on the biology and control of this species, especially its germination, longevity and its response to herbicides.

References

Calvo TR, Cardoso CRP, Moura ACda S, Santos LCdos, Colus IMS, Vilegas W, Varanda EA, 2011. Mutagenic activity of Indigofera truxillensis and I. suffruticosa aerial parts. Evidence-based Complementary and Alternative Medicine, 2011:Article ID 323276. http://www.hindawi.com/journals/ecam/2011/323276/

Cannon PF, 1999. Parodiella hedysari. [Descriptions of Fungi and Bacteria]. IMI Descriptions of Fungi and Bacteria, No. 141. Wallingford, UK: CAB International, Sheet 1408.

Carli CBde A, Quilles MB, Maia DCG, Lopes FCM, Santos Júnior R, Pavan FR, Leite CQF, Calvo TR, Vilegas W, Carlos IZ, 2010. Antimycobacterial activity of Indigofera suffruticosa with activation potential of the innate immune system. Pharmaceutical Biology, 48(8):878-882.

FAO, 2013. Common weeds in Vanuatu. FAO. http://www.fao.org/ag/agp/AGPC/doc/Publicat/FAOBUL2/B201.htm

Figueiredo APMde, Medeiros RMT, Dantas FPM, Leite ALD, Fighera RA, Riet-Correa F, 2012. Experimental poisoning by Indigofera suffruticosa in goats and sheep. (Intoxicação experimental por Indigofera suffruticosa em caprinos e ovinos.) Pesquisa Veterinária Brasileira, 32(2):126-130. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-736X2012000200006&lng=en&nrm=iso&tlng=pt

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Luiz-Ferreira A, Cola M, Barbastefano V, Farias-Silva E, Calvo TR, Almeida ABAde, Pellizzon CH, Hiruma-Lima CA, Vilegas W, Souza-Brito ARM, 2011. Indigofera suffruticosa Mill as new source of healing agent: involvement of prostaglandin and mucus and heat shock proteins. Journal of Ethnopharmacology, 137(1):192-198. http://www.sciencedirect.com/science/article/pii/S0378874111003291

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Salvador Ide S, Medeiros RMT, Pessoa CRM, Dantas AFM, Sucupira Júnior G, Riet-Correa F, 2010. Poisoning by Indigofera suffruticosa (Leg. Papilionoideae) in cattle. (Intoxicação por Indigofera suffruticosa (Leg. Papilionoideae) em bovinos.) Pesquisa Veterinária Brasileira, 30(11):953-957. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-736X2010001100009&lng=en&nrm=iso&tlng=pt

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Links to Websites

Contributors

30/03/2013 Original text by:

Chris Parker, Bristol, UK 

Distribution Maps