When a tree is injured by fire or disease sap runs into the wound much like coagulating blood. When harvested it yields a highly resinous tinder popularly called fatwood in the USA. It is commercially sold here in 5lb bags with sticks @ 8" X 1/4". They can be shaved into kindling or readily ignited with a good flame source to start your firewood. They do poduce considerable soot and should be reserved for starting fires.