"Flames are the tongues of fire"
While trying to understand more and more on fire worshipping, I have come across an interesting piece of information and it is from the book " At The Eleventh Hour" - A biography of Swami Rama.
Once Swami Rama was talking Sombari Baba, asks about the colors of flame to understand why they change from time to time. To this query, Sombari Baba says they are tongues of fire and there are seven in all with different color with specific functions. Before starting the fire ritual, the fire with all those tongues was invoked. Depending on the intention of offering and characteristics of the offering, specific tongue comes forward to accept it.