The
glaucophytes, also known as
glaucocystophytes or
glaucocystids, are a small group of rare freshwater microscopic
algae. Together with the
red algae (Rhodophyta) and the
green algae plus land plants (
Viridiplantae or Chloroplastida), they form the
Archaeplastida. However, the relationships among the red algae, green algae and glaucophytes are unclear, in large part due to limited study of the glaucophytes.