Plants have chlorophyll and an alternation of generations .
They also differ in that the sporophyte and gametophyte are heteromorphic , that is the two generations look and develop differently from each other. Systematics within the Plantae is based on a number of features in addition to life-cycle characteristics. The presence of stomata in all plants but the Hepaticophyta suggests that they were the earliest group to diverge. Relationships among the various groups of pteridophytes are poorly understood, though much research is being concentrated on this group. For more information about the systematics of the land plants , visit the Tree of Life .