Which is this flower shrub that blooms in the hills of South India once in twelve years?

Neelakurinji in Malayalam & Tamil or 'Strobilanthes kunthiana', is a shrub that is found in the Shola forests of the Western Ghat mountains in Kerala, Karnataka, and Tamil Nadu. Nilgiri Hills, which literally means the 'Blue Mountains', got its name from the purplish-blue flowers of Neelakurinji that blossoms only once in 12 years. This species also blooms in Munnar hills, Kerala, and the Coorg hill station, Kodagu district in Karnataka.

These rare flowers, which grow up to 30 to 60 centimetres (12 inches to 24 inches) high, bloom only once in the plant’s lifetime, following which the plant perishes. Different areas of the Western Ghat mountains have the flowering of the Neelakurinji during different spans of twelve years. The two scenic hillocks of Karnataka, Mandalpatti and Kote Betta in Kodagu district are bathed in purple as Neelakurinji flowers have taken over the hills like a purple 'tsunami' recently. This flowering process has started in the second week of August this year.