What is "oldenlandia umbellata"

Chay root \Chay" root`\ [Tamil sh[=a]ya.] The root of the Oldenlandia umbellata, native in India, which yieds a durable red dyestuff. [Written also choy root.]

Oldenlandia umbellata (called chay root or choy root, from its Tamil name, chaaya ver) is a low-growing plant native to India. A colour-fast red dye can be extracted from the root bark of (preferably) a two-year-old plant. Chay root dye was once used with a mordant to impart a red colour to fabrics such as calico, wool, and silk.

It is grown on the Coromandel Coast in India.