Primoplantae

Archaeplastida Temporal range: Ectasian - Present, 1300–0Ma Had'n Archean Proterozoic Pha.
Trees, grasses and algae in and around Sprague River, Oregon
Scientific classification
Domain:	Eukaryota
(unranked):	Diaphoretickes
(unranked):	Archaeplastida Adl et al., 2005
Subgroups
Red algae Glaucophytes Plantae or Viridiplantae (land plants and green algae)
Synonyms
Plantae Cavalier-Smith, 1981 Primoplastobiota Reviers, 2002 Primoplantae Palmer et al. 2004

The Archaeplastida (or Plantae sensu lato) are a major group of eukaryotes, comprising the red algae (Rhodophyta), the green algae, and the land plants, together with a small group of freshwater unicellular algae called glaucophytes. The chloroplasts of all these organisms are surrounded by two membranes, suggesting they developed directly from endosymbiotic cyanobacteria. In all other groups besides the amoeboid Paulinella chromatophora, the chloroplasts are surrounded by three or four membranes, suggesting they were acquired secondarily from red or green algae.

The cells of the Archaeplastida typically lack centrioles and have with flat cristae. They usually have a cell wall including cellulose, and food is stored in the form of starch. However, these characteristics are also shared with other eukaryotes. The main evidence that the Archaeplastida form a monophyletic group comes from genetic studies, which indicate their plastids probably had a single origin. This evidence is disputed. Based on results to date, alternative evolutionary scenarios to a single primary endosymbiosis is not possible to confirm or refute. Photosynthetic organisms with plastids of different origin (such as brown algae) do not belong to the Archaeplastida.

The archaeplastidans fall into two main evolutionary lines. The red algae are pigmented with chlorophyll a and phycobiliproteins, like most cyanobacteria, and accumulate starch outside the chloroplasts. The green algae and land plants – together known as Viridiplantae (Latin for "green plants") or Chloroplastida – are pigmented with chlorophylls a and b, but lack phycobiliproteins, and starch is accumulated inside the chloroplasts. The glaucophytes have typical cyanobacterial pigments, and are unusual in retaining a cell wall within their plastids (called cyanelles).