Indigo dye

Indigo dye is an organic molecule^[1] that appears dark blue or indigo when applied to cloth. While the indigo plants are the most famous source of indigo dye, other plants are able to produce the same compound, including woad,^[2] Pink Strobilanthes,^[3] Japanese indigo,^[4] and Yoruba indigo.^[5]

References

1. "PubChem".
2. "Indigo dyeing from Isatis tinctoria L.: From medieval to modern use". Dyes and Pigments.
3. "Island blues: indigenous knowledge of indigo-yielding plant species used by Hainan Miao and Li dyers on Hainan Island, China". Journal of Ethnobiology and Ethnomedicine.
4. "Exploring the Origins of Aizome―Traditional Indigo Dyeing".
5. "Yoruba indigo. (Lonchocarpus cyanescens, Benth.)". Bulletin of Miscellaneous Information (Royal Botanic Gardens, Kew).