Pigments and Spectrum

Blue roses aren't real because... there is no blue pigment in the rose.

Spectrum colors. In plants, the molecules that absorb visible light are called anthocyanidins. Found in the vacuole of epidermal cells, they are what gives flowers colour : blue, red, mauve, pink or orange, these colours depend on the type of anthocyanidin.

For example :

1. Luteolinidin → Orange
2. Pelargonidin → Red
3. Cyanidin → Magenta
4. Delphinidin → Violet

Blue Rose

 There is no blue pigment in the rose, even though many flowers, mainly perennials (garden irises, lupine, gentian, etc.), annuals or biennials (pansy, forget-me-nots, petunias, etc.), as well as clematises, are blue in colour...

This is in fact due to multiple and complex combinations of chromophores which are anthocyanidins with other molecules of epidermal cells.

For example :

• - co-pigmentation

This is the interaction between anthocyanidins and other vacuole molecules (polyphenols), called co-pigments. This combination has the advantage of protecting the anthocyanidin chromophore against damage due to an increase in pH. Co-pigmentation can also diversify colours with the same chromophore : for example, cyanine chloride is the main anthocyanidin to be found in both wild cornflowers (blue) and most red roses…

• - anthocyanidin-metal complexation

The complexation of metal ions (iron, aluminium, etc.) drawn from the soil, with anthocyanidins (mainly cyanidin and delphinidin) would seem to be cause of the blue colour in some flowers : for example, blue hortensia.

Shades of blue rose

back to the main page