Some plants are parasitic or mycotrophic and may lose the ability to produce normal amounts of chlorophyll or to photosynthesize. Their chloroplasts contain chlorophylls a and b, which gives them their green color.
Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria. However, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria). Historically, plants were treated as one of two kingdoms including all living things that were not animals, and all algae and fungi were treated as plants.
They form the clade Viridiplantae (Latin for 'green plants') that includes the flowering plants, conifers and other gymnosperms, ferns and their allies, hornworts, liverworts, mosses and the green algae, and excludes the red and brown algae. Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae.
