Indigofera trita subsp. scabra
(Asian Indigo)

Preferred Common Name

• Asian Indigo

Other Scientific Names

• Indigofera keyensis Small
• Indigofera laotica Gagnep.
• Indigofera mucronata var. keyensis (Small) Isely
• Indigofera rutschuruensis De Wild.

International Common Names

• Spanish: añil; azulita; frijolillo; frijolillo de llano

Local Common Names

• India: three-leaved indigo
• USA/Florida: Florida indigo

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

Fabaceae is one of the largest families of flowering plants. This family includes about 745 genera and 19500 species which can be found throughout the world growing in a great variety of climates and environments (Stevens, 2012). The genus Indigofera includes over 750 species of shrubs, shrublets, perennial herbs, or rarely annual herbs or small trees (Flora of China Editorial Committee, 2014). Within the species I. trita, there are four infraspecific taxa accepted:

•      Indigofera trita var. maffei (Chiov.) Ali
•      Indigofera trita var. marginulata (Wight & Arn.) Sanjappa
•      Indigofera trita subsp. scabra (Roth) De Kort & G.Thijsse
•      Indigofera trita var. subulata (Poir.) Ali

The subspecies I. trita subsp. scabra is considered native to India, Laos, Sri Lanka, Thailand, and Madagascar (ILDIS, 2014). This subspecies is also listed as native and with a conservation status of endangered in Florida (USA). It has previously been known as Indigofera mucronata var. keyensis, associated with its presence in the Florida Keys.

Erect, woody herbs or shrublets, 30-200 cm high; branches erect to horizontal, pinkish to light green, coarsely strigose, biramous hairs short, white, adpressed with equal arms. Leaves long, 5-7-foliolate, often basal leaves 3-foliolate; stipules 1-2 x 0.3-0.5 mm, narrowly triangular, hairy outside; petioles 1-2.5 cm long, canaliculate above, hairy; rachis 5-12 mm long; stipellae absent; petiolules 1-1.5 mm long; leaflets 3, very rarely 5, opposite. Racemes 5-15 cm long. Flowers pink to brick red, 4-5 mm long; bracts 1-1.5 mm long, narrowly triangular, caduceus; pedicels up to 1.2 mm long. Calyx adpressed white pubescent, cup 0.5-1 mm long, teeth 1-1.5 x 0.5 mm, narrowly triangular. Standard 3.5-4.5 x 3-4 mm, orbicular, sometimes broadly obovate, rounded and mucronate at apex, adpressed strigose on the back; wing petals 3-4 x 1 mm, glabrous ciliate along margins; keel petals 3-4 x 1-1.5 mm, strigose outside towards the tip, ciliate along margins, lateral spur ca 0.6 mm long. Staminal sheath 3-4 mm long; anthers approximately 0.5 mm long. Ovary approximately 3 mm long, linear, glabrous, up to 10-ovuled; style 1-1.5 mm long, glabrous. Pods more than 3 cm long, curved, dropping; seeds 6-10, approximately 2 x 1.5 mm, subtetragonous, yellow, dark-brown, smooth (India Biodiversity, 2014).

Many species in the genus Indigofera have been introduced throughout the tropics to be used as ornamentals, forage, groundcovers, and medicinal herbs (PROTA, 2014). I. trita subsp. scabra was probably introduced in the West Indies to be used as a forage and ground cover species but there is no known date of introduction available for this region (PROTA, 2014). 

Soil drainage

• free

Soil reaction

• neutral

Soil texture

• light
• medium

I. trita subsp. scabra is considered weedy and invasive in the Dominican Republic where it is invading open ground, ruderal areas, disturbed sites and forest edges (Kairo et al., 2003). 

• Proved invasive outside its native range
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Fast growing

• Altered trophic level
• Modification of nutrient regime
• Modification of successional patterns
• Monoculture formation
• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - monopolizing resources
• Induces hypersensitivity
• Rapid growth

• Highly likely to be transported internationally deliberately

I. trita subsp. scabra is used as a forage and ground cover plant in the West Indies. It is also planted as an ornamental (Kairo et al., 2003; PROTA, 2014).