Late 19th century; earliest use found in Alexander Winchell (1824–1891). From phyto- + -genic. Compare French phytogénique (rare; 1862 designating a period in biological history).
Definition of phytogenic in US English:
phytogenic
adjectiveˌfʌɪtəʊˈdʒɛnɪk
Formed by or derived from plants.
Origin
Late 19th century; earliest use found in Alexander Winchell (1824–1891). From phyto- + -genic. Compare French phytogénique (rare; 1862 designating a period in biological history).