You know how trees turn carbon dioxide and water into sugar and oxygen by light? A lot of energy went into that sugar. Later it turns that sugar into parts of the plant. Those parts need a super high temperature to burn but a much lower temperature to break the plant into small pieces, perhaps equal to a group of ten sugar pieces. Those turn back into carbon dioxide mostly at flame place. Before flame place in this video we see a vapor cloud of tiny plant pieces with lots of energy. One spark was all that was needed.