Plant colour


Natural sources

The colour of the plants is due to naturally coloured substances. The result of the existence of these pigments is varied, as is the colour palette that appears in flowers or fruit. There are other factors that influence the colour of flowers and make the same plant species lighter or darker, one shade or another, or mix with other shades.

An infinity of colours

The enormous number of colours found in flowers is created by only three natural groups: flavones, yellow dyes present in the cellular juice, carcolourants with yellow to red hues present in the protoplasm, anthocyanins with red to dark purple almost black hues also found in the cellular juice. The flowers are never black, as is said of black roses or black tulips.

Factors in nature

Plant colour is influenced by light, temperature, humidity and other factors. Many plants grown in full light contain more anthocyanin pigments in their cell juice. The more intensely lit parts of the petals are more heavily pigmented than the shaded parts. In other cases it is easy to see that light or lack of light does not influence pigmentation: beetroot, radish. However a flower that is in bloom at the base when you bring it into the house opens and the other flowers at the top of the bud, the last to appear, will not have petals the colour of their sisters.

Natural pigments

The colouring of fruit and leaves is due to pigments in their skin. The green is given by the chlorophyll pigment.

The diversity of colours in herbal plants is attributed to four groups of pigments: porphyrins, caratenoids, flavones, anthocyanins, xanthocyanins (yellow-orange, yellow-reddish) they appear more nuanced in aa more alkaline environment, and in the presence of iron solutions varies towards green-oliv, green-browned.

The colour of anthocyanin pigments varies with pH-The cell juice is red in acidic pH, blue in alkaline and purple in neutral pH. Sulphur dioxide can discolour them.

Temperature variation can influence the colour, for example: lilacs forced in winter, in greenhouses, at over 30C have white flowers even if they are a lilac variety, but at temperatures of 26-27C regains its variety-specific colour.

Colours and geographical region

In alpine and circumpolar areas, with low temperatures, the colouring of flowers is darker in red, purple, blue, because these pigments have the function of trapping hot radiation, either to protect against harmful ultraviolet radiation to the enzyme chemist.

In the northern countries, plants with red, blue and purple flowers (61%), those with white flowers (22%) and yellow/green flowers (17%) predominate, while in the temperate zones, more yellow/green flowers followed by white flowers predominate. In the steppes they have whitish colours and less often blue and the latter lighter.

In the equatorial zones, although with higher temperatures, the plants still have a varied colour because light is diffused and because of the tiered vegetation and vines. Spring flowering plants, although they flower early in the spring, still have a light, white, greenish or purple colour at low temperatures, because the light colour has a thermoregulating effect.