Viridiplantae

Viridiplantae (New Latin for "green plants"), also known as kingdom Plantae sensu stricto ("plants in a narrow sense"), is a clade of mostly autotrophic eukaryotes that constitutes the largest group within the predominantly photosynthetic superclade Archaeplastida, with around half a million known species that include all green algae and land plants (embryophytes, which evolved from freshwater green algae known as streptophytes). They are important primary producers in both aquatic (marine and freshwater) and terrestrial ecosystems, and are significant contributors to the Earth's oxygen, carbon and water cycles. Compared to the archaeplastidian sister groups Rhodaria (red algae, rhodelphidians and picozoans) and Glaucophyta ("grey algae"), Viridiplantae are unique in that almost all members (with the exception of parasitic plants and the heterotrophic algae Prototheca) have chloroplasts with both chlorophyll a and chlorophyll b (the latter absent in other archaeplastidians) but lack phycobiliproteins (which are present in other archaeplastidians) — thus typically presenting an untainted green color — and carbohydrates produced by photosynthetic carbon fixation is stored as starch directly inside the chloroplasts or in specialized non-pigmented plastids known as amyloplasts. Their cell walls consist of a network of semicrystalline cellulose microfibrils hydrogen-bonded with minor amounts of hemicellulosic polysaccharides such as xyloglucan and glucuronan, or with the cellulose replaced by mannans as well as sulfated/pyruvylated galactans and arabinans; while "later-diverging charophytes" (charophyceans, coleochaetophyceans, zygnematophyceans and embryophytes) have a framework of cellulose microfibrils embedded in a matrix of pectins, hemicelluloses, arabinogalactans and extensins as well as lignin or lignin-like polymers. In 2005, Sina Adl and colleagues proposed the name Chloroplastida for the group. In 2012, Frederik Leliaert and colleagues suggested a revised taxonomy of the Viridiplantae. In 2019, M. Leebens-Mack and colleagues proposed a phylogeny based on analysis of over a thousand plant genomes. It renders the former "chlorophyte algae" and "streptophyte algae" paraphyletic,...