Curcuma caesia

Curcuma caesia, black turmeric or black zedoary is a perennial herb with bluish-black rhizome, native to North-East and Central India. Black turmeric is also sparsely found in the Papi Hills of East Godavari, West Godavari, and the Khammam districts of Andhra Pradesh. The rhizome of black turmeric has a high economic value owing to its medicinal properties. The Black turmeic's  rhizome is actually purple, compared to the orignal orange turmeric.

In west Bengal, the rhizome of the plant is used in Kali Puja, and hence the plant is called Kali haldi. By etymology, Kali is the feminine form of Kala, which means black color and hence the plant is termed as black turmeric in English. This species has been regarded as endangered by the central forest department of India due to biopiracy.