Douglas Harper's Etymology Dictionary
phylo-
before vowels phyl-, word-forming element from comb. form of Greek phylon, phyle "a tribe," also "a political subdivision in ancient Athens," from base of phyein "to bring forth, produce, make to grow," whence also physis "nature" (see physic).
Wiktionary
phylo-
pre. Pertaining to or derived from tribes, races or phylum