The Moolavar is Purushothaman in Bujanga Sayanam facing East.
Thaayaar - Poorvadevi, Poornavalli.
The sthala vriksham is Vaazhai (Plantain)
Siva Peruman, had plucked off one of Lord Brahma's heads because he had lied. But it was still a sin & the skull got stuck to his hand. He got Mahalakshmi to give him alms in the skull & was rid of his sins & doshams.
There are separate sannadhis for Siva, Parvathi, Brahma, Saraswathi...
Since Lord Siva appears as Bikshaadanar in this temple, the sthalam is also called Bikshaandar Koil.
Thirumangaialwar - 1399