From which part of turmeric, is the turmeric powder obtained?

Turmeric powder is obtained from the dried rhizome of the plant Curcuma longa, which belongs to the ginger family [3]. The rhizome is an underground stem that is thick, fleshy, and ringed with the bases of old leaves [4]. After harvesting, which typically occurs 7-9 months after planting, the fresh rhizomes are washed, boiled in water to reach a soft stage, and then sun-dried for 10-15 days [3]. Once fully dried, these rhizomes are ground into the fine, yellow-orange powder commonly used as a spice and medicinal agent. While some sources colloquially refer to it as a 'root' due to its underground growth, botanically it is a rhizome, and the plant is sterile, meaning it does not produce seeds for propagation [1].

Sources

1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 12: Major Crops and Cropping Patterns in India > Turmeric (Curcuma longa) > p. 68
2. [3] https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/curcuma-longa
3. [4] https://www.ncbi.nlm.nih.gov/books/NBK92752/