Palo Santo (Burserea sarmientoi ) is also known as Holy Wood, Sacred Wood and St Antony's Wood. The tree originated in Peru and the wood is burnt to produce a fragrant smoke. It was used by the Incas for purifying and cleansing and to get rid of evil spirits, or bad luck.
Palo Santo is a protected species in South America and its harvesting, usually by collecting fallen branches, is closely monitored.
In 3.01 The Magnificent Seven Tamara states that it is "toxic to demons like holy water", and that it can be used, in stake form, to immobilize demon possessed humans while they are exorcised.