<P> Flower evolution continues to the present day; modern flowers have been so profoundly influenced by humans that many of them cannot be pollinated in nature . Many modern, domesticated flowers used to be simple weeds, which only sprouted when the ground was disturbed . Some of them tended to grow with human crops, and the prettiest did not get plucked because of their beauty, developing a dependence upon and special adaptation to human affection . </P> <Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (January 2018) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (January 2018) (Learn how and when to remove this template message) </Td> </Tr> <P> Many flowering plants reflect as much light as possible within the range of visible wavelengths of the pollinator the plant intends to attract . Flowers that reflect the full range of visible light are generally perceived as white by a human observer . An important feature of white flowers is that they reflect equally across the visible spectrum . While many flowering plants use white to attract pollinators, the use of color is also widespread (even within the same species). Color allows a flowering plant to be more specific about the pollinator it seeks to attract . The color model used by human color reproduction technology (CMYK) relies on the modulation of pigments that divide the spectrum into broad areas of absorption . Flowering plants by contrast are able to shift the transition point wavelength between absorption and reflection . If it is assumed that the visual systems of most pollinators view the visible spectrum as circular then it may be said that flowering plants produce color by absorbing the light in one region of the spectrum and reflecting the light in the other region . With CMYK, color is produced as a function of the amplitude of the broad regions of absorption . Flowering plants by contrast produce color by modifying the frequency (or rather wavelength) of the light reflected . Most flowers absorb light in the blue to yellow region of the spectrum and reflect light from the green to red region of the spectrum . For many species of flowering plant, it is the transition point that characterizes the color that they produce . Color may be modulated by shifting the transition point between absorption and reflection and in this way a flowering plant may specify which pollinator it seeks to attract . Some flowering plants also have a limited ability to modulate areas of absorption . This is typically not as precise as control over wavelength . Humans observers will perceive this as degrees of saturation (the amount of white in the color). </P>

What do you call the center of a flower