Indigo is a deep and rich color between the shades of violet and blue. Historically, indigo dye was extracted from several species of plants to produce the distinctive blue color prized for textile dying and other uses. However, when most people think of the “indigo flower” they are referring specifically to two species – Indigofera tinctoria and Indigofera suffruticosa. These tropical plants produce a blue dye in their leaves that can be extracted and used as a natural blue dye. So which of these plants is the “true” indigo flower? Let’s take a closer look at each species.
Indigofera tinctoria
Indigofera tinctoria, also known as true indigo, is a species of flowering plant in the bean family Fabaceae. It is a tropical plant native to Asia, likely India. I. tinctoria has been cultivated as the primary source of indigo dye across Asia and Africa for centuries. The plant itself grows to about 1-2 meters tall as an annual or short-lived perennial. It has light green pinnate leaves and pink or purple flowers when it blooms.
Here are some key facts about I. tinctoria:
- Native to India and tropical Asia
- Natural source of indigo dye used worldwide for centuries
- Leaves and stems produce indoxyl, the precursor to indigo dye
- Plant grows 1-2 meters tall
- Has light green pinnate leaves
- Pink or purple flowers when blooming
- Cultivated as an annual or short-lived perennial crop
To produce indigo dye from I. tinctoria, the plant is harvested, soaked, and fermented to convert the indoxyl into indigo. The indigo is then extracted and processed into a dye. Traditionally, this process is done manually and requires skill and care.
Here is a table summarizing some of the key information on I. tinctoria:
| Common Names | True indigo, indigo, fustic |
|---|---|
| Scientific Name | Indigofera tinctoria |
| Native Range | India, Asia |
| Physical Description | Light green leaves, pink/purple flowers, 1-2 m tall |
| Key Uses | Source of natural indigo dye |
Given its long history of cultivation as the primary source of indigo dye worldwide, I. tinctoria has a good claim to being the “true” indigo plant.
Indigofera suffruticosa
Indigofera suffruticosa is another species of indigo plant that serves as an important source of indigo dye in certain regions. Like I. tinctoria, it is a member of the bean family Fabaceae. This species is considered to be native to the tropical areas of the Americas, unlike I. tinctoria which originated in Asia.
Some key facts about I. suffruticosa:
- Native to Central and South America
- Key source of indigo dye in the New World since pre-Columbian times
- Shrub reaching up to 2 meters tall
- Pink, red, or white flowers when blooming
- Used just like I. tinctoria for indigo production
- Less cold tolerant than I. tinctoria
I. suffruticosa was utilized by indigenous civilizations of the Americas to produce blue dye for textiles and art. The plant was later adopted for colonial indigo production. Today, it continues to be cultivated for specialty indigo production, particularly in Central and South America.
Here is a summary table of I. suffruticosa:
| Common Names | West Indian indigo, Guatemalan indigo |
|---|---|
| Scientific Name | Indigofera suffruticosa |
| Native Range | Central and South America |
| Physical Description | Shrub to 2 m tall, pink/red/white flowers |
| Key Uses | Source of indigo dye in the Americas |
Although I. suffruticosa has a long history of use for producing blue dye in Central and South America, it remains secondary to I. tinctoria globally. I. tinctoria is more widely distributed and was the main source of indigo dye production worldwide.
Comparing the Two Indigo Species
When comparing I. tinctoria and I. suffruticosa, there are some notable similarities and differences:
- Similarities
- Both produce indoxyl, the precursor to indigo dye
- Both used through history as source of blue dye
- Both have pink or purple flowers when blooming
- Both are tropical plants suited to warm climates
- Differences
- I. tinctoria is native to Asia; I. suffruticosa is from the Americas
- I. tinctoria has been the primary global source; I. suffruticosa more regional
- I. tinctoria is more cold tolerant and adaptable
- I. suffruticosa can grow taller, up to 2 meters
While closely related and utilized in similar ways, each species has different origins and has been used on different scales – one global and one more localized.
Conclusion
Based on the evidence, Indigofera tinctoria stands out as the “true” indigo plant. While I. suffruticosa has historical importance in Central and South America, I. tinctoria has been the primary source of indigo dye worldwide for centuries. Specifically:
- I. tinctoria originated in India and Asia, which were the center of historical indigo production.
- It has been traded and cultivated globally since ancient times as the main blue dye source.
- I. tinctoria is more adaptable and cold tolerant, allowing it to grow in more regions.
- While chemically identical, indigo from I. tinctoria is considered superior for dyeing.
For these reasons, I. tinctoria can be considered the “true” indigo plant that has defined the color indigo for textiles worldwide. I. suffruticosa, however, still holds an important regional role and legacy in the Americas. Both plants contribute to the rich human history of natural indigo dyes. Going forward, eco-conscious dye production may look back to these ancient indigo sources once again.
References
Gilbert, P. (1980). Indigo production in the eighteenth century. Economic Botany, 34(1), 39-41.
Jenny, H. (2001). Indigo production in India: technical devices used in the recycling of bath residues prior to 1850, and resistance of fabrics to washing and light. Dyes in History and Archaeology, 185-197.
Cardon, D. (2007). Natural dyes: sources, tradition, technology and science. Archetype publications.
Polhemus, T. (2016). Indigo and indigo dyeing. In Fashion and anti-fashion (pp. 105-128). Thames & Hudson.