"Green" has a common use among the public. Both natural and social environment have an important effect on this expression. People tend to explain the scientific concepts using well-known situations which they intensively see around the living area. In this sense, photosynthesis is one of the most important biological concepts including social and cultural connections. Therefore this study mainly investigated the importance of "green" in explaining such concept. Data obtained from the document analysis of textbooks and content analysis of Primary School Teaching Students' (PSTS) answers to open ended questions. Evaluating the writings belongs to 200 PSTS, it is understood that most of them could not explain the photosynthesis of "non-green" plants scientifically. They think that this explanation is mainly based on the "green" pigment dominance of plants. Additionally it is an expected result of intensive and haphazardous repeatings as "green plants" instead of only "plants" originated from school education and public use. In fact, "green" is not a requirement for explaining the photosynthesis reaction of plants. This unecessary use in explaining the photosynthesis function of "non-green" plants is an interesting result for identifying the connection between scientific concepts and socio-cultural issues.