What do plants have to do with coal?

Plants are the primary source of coal formation. Millions of years ago, large amounts of plant material, such as ferns and trees, accumulated in swampy environments and underwent a process called coalification, where heat and pressure transformed the organic matter into coal. This process took place over millions of years, resulting in the rich deposits of coal we mine today. Thus, coal is essentially ancient plant matter that has been preserved and altered over geological time.