The Nilgiri Hills in South India are literally called the Blue Mountains due to the blue haze they appear to have from a distance, caused by the vast Strobilanthes kunthianus flowers (Neelakurinji) that bloom once every 12 years. The name comes from Sanskrit 'Nil' (blue) and 'Giri' (mountain). Aravalli, Vindhya, and Sahyadri (Western Ghats) are other mountain ranges without this specific epithet.