Estimates for the number of species included in the plant kingdom hover around 270,000 to over 300,000, with the great majority of this diversity occurring within flowering plants (approximately 235,000 species), followed by about 11,000 species of ferns and 9000 species
of mosses. The degree of our taxonomic knowledge of various groups is not equal, so while the estimate for the number of conifer species may be quite good, the estimate for flowering plants may require substantial revision as areas of high diversity become better understood.