Glaucophytes

The glaucophyte algae are unicellular freshwater algae with less than two dozen species, which are ancestral in the Archaeplastida clade. They have a blue-green appearance, which gives them their name (glaukós meaning “blue-green”), and this color has been coopted from their cyanobacterial endosymbiont. These plastids are called cyanoplasts, which predate chloroplasts and retain many ancestral plastid features from the cyanobacterial donor. Studying glaucophytes and their cyanoplasts increases our understanding of the evolution of the chloroplast (Keeling, 2004).