Variegation in plants is highly sought after in the horticultural and houseplant community. These plants, with unusual colors in splotches across the leaves, are considered unique and often find their way into the houseplant community.
But what causes variegation, and why do plants develop it in the first place?
Is it an adaptation to the plant’s natural predators, or a way to send a signal to new pollinators?
After all, plants are sessile organisms. In their natural habitat, they can’t simply walk away like an animal could, they must adapt themselves to the environment.
In this HerbSpeak article, you will learn everything about variegation in plants, from why plants develop variegation, whether you can induce variegation, and if lost variegation can come back.
What Causes Variegation?
In short simplicity, variegation is differently colored patches in the leaves and occasionally stems of plants. Often, variegation occurs as a lighter color than the rest of the plant.
In more botanical terms, variegation is a mutation in the chloroplasts which affects the production of chlorophyll, the chemical which turns the plant green. (1)
“Variegation results from a defect that makes chloroplast development unstable, since at least part of the tissues gives rise to normal chloroplasts.”
Variegation can come in the form of splotches, stripes, or other types of patterns. Some variegation patterns can even extend into the blossoms of flowering plants.
Though this phenomenon occurs rarely in nature as it can leave plants at a disadvantage when attempting to capture more sunlight, it is still possible. Most variegated houseplants, however, are the result of a purposeful horticultural development.
Types of Variegation
There are four main types of variegation that affects plants. Each type is caused by a different factor and can affect the plant differently.
Plants develop variegation as a result of viral infection, genetic mutation, or nutrient deficiency. Variegation may also be chemically induced, but this rarely stabilizes, causing the plant to inevitably revert.
Also commonly called “natural variegation,” this type of variegation occurs not from mutation, but from natural patterning in the plant. Calathea spp. is an excellent example of this type of variegation, as the natural patterning is encoded in the plants DNA and passed down to the next generation automatically.
This is the most common type of variegation in household plants, caused by genetic mutation. These plants will have two different chromosomal make-ups, often affecting chlorophyll production. This type of variegation can be identified with plants that have yellow or white areas mixed in with the typical green, often changing pattern erratically in the same leaf.
Though some chimeral variegations are bred to only appear on one half of the leaf, for example, with some Monstera deliciosa ‘Variegata’.
Viral Infection Variegation
Occasionally, variegation is also caused by a viral infection in the leaves. One example of this is the Mosaic virus, known to affect common agricultural crops, hostas, and other outdoor specimens. This type of variegation causes a multicolored mosaic pattern on the sickly leaves as the virus spreads throughout the plant.
You may have seen this in many houseplants without recognizing it as variegation. Peperomia argyreia, or Watermelon Peperomia, is one plant known for this type of variegation. Here, the plants have taken on a reflective, silvery sheen caused by tiny air pockets between the layers of pigmentation in the leaf.
Why Plants Develop Variegation
On an ecological scale, the only real benefit of plants developing variegation is to showcase a distinctive pattern. This is attractive to humans, and may potentially be attractive to pollinators, though no studies have been performed on this.
In the grand scheme of things, variegation rarely occurs in the wild unless it is a pattern-gene mutation which stabilizes over generations; an excellent example of this is Calathea spp. where the patterns are stabilized and naturally appear, though it is not known if this benefits the plant in any way.
Most houseplants have been deliberately cultivated to have new patterns and would not have those patterns in nature.
The loss of chlorophyll in a natural plant species would most often harm the plant before it could do any good. When plants are competing for energy production and growth, a lack of chlorophyll can stunt the plant and place it at a disadvantage.
There are two potential ways that variegation could help plants in the wild – though it is important to note that this is largely speculation, and more studies are needed to provide any conclusive evidence on this:
It has been suggested by a single study that some plants could use variegation as a defensive mechanism to ward away pests that think the plant is already infected.
Likewise, there is some speculation that variegation develops as a way to prevent the plant from taking in too much sunlight as the climate grows warmer or the sun’s rays grow too intense for the plant.
Can You Induce Variegation in Plants?
While it is possible to induce variegation in plants, it can be difficult and is often something that should be left to a licensed horticulturalist, especially if you are attempting to induce variegation chemically. Viral variegation can prove fatal to the plant and may infect other plants in the area.
If you are lucky and get a variegated leaf to mutate in an otherwise stable plant, you can attempt to propagate that mutated leaf and carefully cut back any new reverted growth to encourage more variegation.
Can Variegation Come Back?
When cultivating variegated plants, it’s not uncommon for the mutation in the chlorophyll – the cause of most variegation – to be unstable. This can cause the chloroplasts to return to their non-variegated form.
A commonplace example of this is seen in Golden Pothos (Epipremnum aureum) where the brilliant yellow-gold and green leaves will slowly turn solid green again.
This reversion is an adaptation which allows the plant to return to a form that it can thrive better in. This might be due to waterlogged soil, a lack of light, changes in temperature, or many other factors.
Unfortunately, it is not possible for variegation to come back once the chlorophyll has stabilized in its new reverted form. Once a leaf turns green, it is unlikely to turn variegated again.
In fact, houseplants are not the only type of plant that are affected by variegation loss. This phenomenon occurs even in the wild with plants that are naturally variegated.
If you purchased a variegated plant which is starting to revert, it might not be right to blame the seller for a “faulty product,” but the plant’s natural genetic instability which gives it a tendency to revert for better growth.
Variegation is often the result of genetic mutation, and that means that it can indeed go both ways.
How Do You Encourage Variegation If You Start Losing It?
Fortunately, there is a silver lining if you start to lose variegation in your plant. While you can’t reverse the process, you can slow it significantly. Below are the three main ways you can slow variegation loss in plants:
- Give it the right amount of light.
This is especially common in plants that are losing variegation but also have stunted growth or leggy stems, which are other signs that it is not getting enough light. Typically, bright indirect light does best. You may need to purchase a grow light that mimics the spectrum of sunlight if you get poor lighting indoors.
- Prune off new reverted leaves.
Pruning off new leaves that appear reverted can help you maintain the variegation you have. With any luck, the plant will begin producing new leaves that are variegated as well, especially if you provide the plant with enough light.
- Minimize temperature shock.
Plants can begin reverting due to temperature changes. Because variegation is overall disadvantageous for a plant in competing with other plant neighbors for light, therefore photosynthesis, therefore energy and life, it’s likely to start attempting to revert if it believes the environment is becoming dangerous to it. This goes for both areas that are too hot as well as areas that are too cold for the plant.
- Wataru Sakamoto, Leaf-variegated mutations and their responsible genes in Arabidopsis thaliana, https://pubmed.ncbi.nlm.nih.gov/12655133/