"microscopic marine algae, the plant parts of the plankton community," 1897, from phyto- + plankton.
Entries linking to phytoplankton
phyto-
word-forming element meaning "plant," from Greek phyton "plant," literally "that which has grown," from phyein "to bring forth, make grow," from PIE root *bheue- "to be, exist, grow."
plankton n.
"organism that lives in a large body of water and is unable to swim against the current," 1891, from German Plankton (1887), coined by German physiologist Viktor Hensen (1835-1924) from Greek plankton, neuter of planktos "wandering, drifting," verbal adjective from plazesthai "to wander, drift," from plazein "to drive astray," from PIE root *plak- (2) "to strike." Related: Planktonic.