New flowers 2009 

A large yellow flower

This article is about the color.

Yellow is the color evoked by light that stimulates both the L and M (long- and medium-wavelength) cone cells of the retina about equally, but does not significantly stimulate the S (short-wavelength) cone cells; that is, light with lots of red and green but not much blue. Light with a wavelength of 570–580 nm is a yellow, as is light with a suitable mixture of somewhat longer and shorter wavelengths. Yellow's traditional RYB complementary color is violet or purple, yellow's colorimetrically defined complementary color in both RGB and CMYK color spaces is blue.

http://encyclopedia.thefreedictionary.com/yellow