Principle purpose of this lecture is to present on Evolutionary Study of Plants. It is tutorial based lecture. Here briefly focus on Cyanobacteria: it is a blue- green algae; hotosynthetic and responsible for the marked increase in Oxygen 2000 million years ago. here also present Cyanobacteria Evidence: DNA shows the first green plants evolved from prokaryotes between 2500 and 1000 million years ago. Finally present on Classification of Plants: Kingdom; Division; Class; Subclass; Order; Family; Genus and Species.