The Collaborative International Dictionary
Phyto-
Phyto- \Phy"to-\ [See Physic.] A combining form from Gr. fyto`n a plant; as, phytochemistry, phytography.
Douglas Harper's Etymology Dictionary
phyto-
word-forming element meaning "plant," from Greek phyton "plant," literally "that which has grown," from phyein "to grow" (see physic).
Wiktionary
phyto-
pre. Pertaining to or derived from plants.