Why Do Flowers Have Different Colors? Science Explained


Everyone has a favorite flower. Some like tulips, some like irises, and some like even more specific flowers, such as white roses. You may be wondering what makes these flowers different and why flowers have different colors or colors at all.

Flowers have different colors because of their DNA. The pigmentation within the flowers and the genetics of their species determine what color the flowers will be. Evolutionary theorists believe this is to help pollinators find the plants easily and help spread their seeds.

Below, I’ll go over some plant DNA basics and talk about the pigmentation, genes, and evolutionary theories behind the different colored flowers in your garden. Additionally, I’ll give you some easy-to-watch videos to help explain this concept and talk about why some flowers may have two or three different colors on the same plant.

The Reason Flowers Have Different Colors

When you think of sunflowers, you may think of the color yellow. For roses, you may think of colors like red and pink. All flowers come in various colors, and though some may match shades, there’s no denying their aesthetic differences.

Scientists and botanists can crossbreed flowers and cultivate them to be a certain color. This is the reason you see mostly red roses on Valentine’s day. It’s not because gardeners are only picking the red ones to sell–it’s because they purposefully grew more red flowers than any other color so you could buy them.

This can be attributed to plant DNA, pigmentation, and genetics.

Plant DNA Basics

Like humans, plants have their DNA. Human DNA is an easier concept for us to grasp because we see it translated into life every day–such as hair color; some of us are blonde, and some of us are brunettes. It all depends on the genes in our DNA. 

Let’s go over a few basic definitions (remembering that DNA and genes are complex subjects, so these basic definitions only scratch the surface of what these words mean):

  • DNA. A deoxyribonucleic acid molecule is made of two chains that coil around each other to make a double helix and determine the genetic instructions that determine the number of characteristics. 
  • Codes. A term used in genetics that describes the way a gene translates the proteins and molecules in DNA/RNA.
  • Genes. A sequence of DNA or RNA.

Plants are similar to humans in this way. Each plant has its strand of DNA that determines its color, how big it’ll grow, what its seeds will look like, etcetera. This YouTube video takes a deep dive into the logistics of plant and human DNA:

Basically, plant DNA is found within their cells. Each cell has a nucleus that contains a chromosome, and within the chromosome is the DNA. Within this DNA, there can be over 45,000 different genes. The genes within DNA that code for color are the pigment and regulatory genes. 

A plant’s DNA isn’t the end all be all, though. Nurture, or the events in a plant’s life can also determine the color of a flower. Humans can dye their hair, and plants can become different colors with a simple food coloring experiment shown in this YouTube video below:

Additionally, if a plant is grown without the proper nutrients, it may become discolored. 

Pigmentation in Flowers Determines Their Colors

The actual thing within the flower that determines its color is pigmentation. The code for pigmentation is in the flower’s DNA. Different pigments are associated with different flower colors. The common colors for flowers are:

  • Carotene (yellow, orange, and brown) 
  • Chlorophyll (green)
  • Cyanidin (dark red and pink)
  • Pelargonidin (bright reds and oranges)
  • Delphinidin (blue and violet)

Any combination of these pigments will make a flower look in various colors. Flowers with white petals have no pigments. 

These pigments can be extracted from flowers and used as a dye. Herbalists and botanists used flower petals to create different colored clothing, furniture, and paint in history. Most popularly, marigolds and dandelions were used to make yellow. 

Genetics Affect the Color of Flowers

Plants have male and female parts that can help them reproduce, typically called the pistol (female) and the pollen (male). You can think of these as flower moms and dads–bees and butterflies will take the pollen from plants and help put it into the pistols of other flowers, creating larger populations of flowers. 

This YouTube video helps to explain the process of reproduction as it pertains to plants: 

To understand the basics of genetics and genotypes, let’s walk through an example. Say a flower is red, and it’s pollinated with an orange flower. These flowers are the same species and often breed with each other. 

Depending on which traits are recessive and dominant, the plant will either be orange or red (or even a combination of the two!). For purple or red-pink flowers, the genotypes are either PP or Pp, respectively. 

Scientists may run the possibilities through a tool called a Punnett square. Check out this YouTube video for more info on those:

Here’s an example Punnett square with the purple (PP) or red-pink (Pp), where purple is pistol and pink-red is the pollinator:

P (pollen)p (pollen)
P (pistol)PPPp
P (pistol) PPPp

In this example, a PP result would make a purple flower, and Pp would make a pink-red flower. For this flower, the results are a 50/50 chance of either. 

How Flowers Are Grown Affects Their Color

Sometimes, the way we grow our plants can affect how they turn out. Even if you’ve put bright yellow flowers into the ground, there’s a chance they may come up a different color if they aren’t growing under the ideal conditions. The following factors can affect the color:

  • Having the wrong pH
  • The lack of a particular nutrient
  • Stressing the plant via temperature, water, or sunlight. 

Evolutionary Theories & Pollination

Now that you know why plants have different colors, you may be wondering why it matters. The bright colors of plants may be why they continue to exist.

Flowers exist and continue to live on because of the way we take care of and cultivate them. Giving them the right water, sunlight, and nutrients can make them grow healthy and strong. 

However, they wouldn’t have the chance to grow strong if they weren’t pollinated in the first place. Evolutionary theorists think that the colors of flowers may be an evolutionary adaptation to help attract the bees, birds, and butterflies that pollinate the flowers.

Why Are There Different Colored Flowers on the Same Plant?

So, if it’s all about genetics, pigment, and DNA, why might your garden have different colors on the same plant?

Different colored flowers on the same plant may have something to do with the conditions they grew under or the genetics of the plant. Just like humans have different color eyes, even if they come from the same parents, sometimes plant genes show up differently.

Genetic mutations can cause flowers on the same plant to become different colors. Wildflower mixes also notoriously have dozens of different colors in the box, and if you’re growing a second or third-generation garden, these colors may have crossbred themselves. 

Final Thoughts

The reason that flowers are blue instead of pink is why some of us have green eyes, and some of us have blue eyes. All of our genetics show up in different ways depending on our parents. Some species of flowers can even be crossbred to produce different results. 

Additionally, if you believe in evolutionary theories, you’ll find that flowers likely have different colors to help pollinators become attracted to them. The bright colors of a sunflower or a tulip will attract bees and butterflies, who will then take their pollen and spread it around.

Sources

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AskthePlantician

Hi I'm Mike, a self-proclaimed plantician (an invented profession to describe a plant enthusiast). Based in Sydney Australia, I enjoy the great outdoors and the greenery things around the garden, in particular, indoor climbing plants.

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