Most plant life needs full spectrum lighting. In early stages of a flowering plant, it would need a blue and green spectrum (achieved with usually metal halide light) and then switched over to a red and orange spectrum (using high pressure sodium lighting). Growing a plant under pure yellow light will most likely make the plant grow quickly, but wiry - the stem will get really long and the top of the plant will most likely fall over eventually). It depends on the plant. Pure yellow light uses the red/orange spectrum and cacti do well in this type of lighting. Houseplants (which prefer blue/green spectrum) would most likely do poorly in "pure yellow light".