“+ noun
also pho·to·taxy ˈfōd.əˌtaksē
( plural phototax·es -|takˌsēz ; or phototax·ies -ˌtaḵsēz)
Etymology: New Latin, from phot- + -taxis
: a taxis in which light is the directive factor (as in the movement of an infusorian toward the lighted side of a vessel) ; also : the orientation of various chloroplasts to light